Method for ammoxidation of paraffins and catalyst system therefor

Abstract: Ammoxidation of propane or isobutane with NH₃ and 0₂ using (1) a mole ratio of paraffin:NH₃ in the range from 2 to 16 and a mole ratio of paraffin:O₂ in the range 1 to 10 and (2) a mixture of particulate catalyst compositions, the first being especially effective to promote formation of an unsaturated nitrile and an olefin from the paraffin, and the second catalyst composition being especially effective to promote the conversion of the olefin to the unsaturated nitrile. Catalytic compositions useful in the process are disclosed.

Description: This invention relates to an improved process for the catalytic ammoxidation of isobutane to methacrylonitrile and, especially, of propane to acrylonitrile. Because of the price differential between propylene and propane an economic incentive exists for the development of a viable catalytic process for conversion of propane to acrylonitrile. Earlier attempts in the prior art to develop an efficient process for the ammoxidation of propane to acrylonitrile produced either insufficient yields or processes that necessitated adding halogen promoters to the feed. The latter procedure would require not only reactors made of special corrosion resistant materials, but also the quantitative recovery of the promoter. The added costs thus eliminated the advantage of the propane/propylene price differential. It is thus an object of the present invention to provide an improved process for the ammoxidation of propane or isobutane to the corresponding unsaturated nitriles. It is a further object of the invention to provide new catalyst systems for such process. Still another object is to provide an improved catalytic ammoxidation process of the above type without the use of halogen promoters. Other objects, as well as aspects, features and advantages, of the present invention will become apparent from a study of the accompanying disclosure and the claims. The foregoing and other objects of the present invention are achieved by the process of the present invention. There are two main features of the present process invention. The first of these is the use of an excess of the alkane feed with relation to NH₃ and molecular oxygen. The second feature, which is used in combination with the high ratio of the paraffin to NH₃ and O₂, is that a combination, i.e., a mixture of catalysts is employed, the first catalyst composition being especially effective to promote formation of an unsaturated nitrile and an olefin from the paraffin, and the second catalyst composition being especially effective to promote the conversion of the olefin to the unsaturated nitrile. Such mixture is the subject of the composition claims herein. In the present application "Rare earths" means elements 57 through 71. British Patent Specifications 1,336,135 and 1,336,136 disclose the use of high ratios of propane or isobutane to ammonia and oxygen, but only single ammoxidation catalysts are used, and the yields of acrylonitrile are extremely poor. US Patent 3,860,534 also discloses use of such high ratios, using a catalyst containing only V and Sb oxides. However, after the catalyst is calcined, it is washed for 24 hours with water and dried, a laborious procedure. US Patent 3,833,638 discloses ammoxidation of propane or isobutane with a (Bi, Te)CeMO oxide catalyst of a defined composition, and the disclosed reactant ratios include an excess of paraffin over NH₃ and O₂, but results are for runs without excess paraffin, and the one-pass yields are low. A.N. Shatalova et al . in Neftekhiniya 8 , No. 4, 609-612 (1968), describe the reaction of propane with oxygen and ammonia using a large excess of propane and a mixture of two catalysts, one of which is described as oxides of metals having dehydrogenating characteristics at 550 and 600°C. At 500°C little or no acrylonitrile was produced. Rather large amounts of propionitrile and acrolein were made per mole of acrylonitrile produced. The per pass conversion of propane to acrylonitrile was generally 2-4 percent with selectivity to acrylonitrile being from 12 to 33 percent. In the present process when applied to propane ammoxidation a small amount of propylene is produced in relation to the unreacted propane in the effluent. Thus the propane effluent containing propylene in the amount of up to 8 mole percent, but usually no more than 6 mole percent, of the amount of propane plus propylene can comprise the substrate feed to the present process. In general the feed to the process can contain one or more C₃ to C₅ olefins. The C₃ to C₅ olefin content of the feed to the present ammoxidation process can contain from zero to 8 mole percent of such olefin(s), based on the moles of paraffin plus olefins fed, and this feed can be from any source. Although larger amounts of C₃ to C₅ olefins may be present in the substrate paraffin feed, usual amounts are as stated, and the usual olefin is that corresponding to the particular paraffin fed to the reaction zone of the present process. According to the present invention there is provided a process for the ammoxidation of a paraffin selected from propane and isobutane to acrylonitrile or methacrylonitrile which comprises contacting in a reaction zone said paraffin in the vapor phase in admixture with ammonia, molecular oxygen, and optionally an inert gaseous diluent, with an intimate particulate mixture of a first catalyst composition and a second catalyst composition, said feed to the reaction zone containing a mole ratio of paraffin:NH₃ in the range from 2 to 16 (usually 3-7), and a mole ratio of paraffin to O₂ in the range from 1 to 10 (usually 1.5-5), said first catalyst composition being 10-99 weight percent of a diluent/support and 90-1 weight percent of a catalyst having the components in the proportions indicated by the empirical formula: VSb m A a H b C c T t O x formula (1) where A is one or more of W, Sn, Mo, B, P and Ge; and includes at least 0.2 atoms of W; H is one or more of Fe, Co, Ni, Cr, Pb, Mn, Zn, Se, Te, Ga, In and As; C is one or more of an alkali metal and Tl; T is one or more of Ca, Sr and Ba; and where m is from 0.01 and up to 20; a is 0.2-10; b is 0-20; c is 0-20 (usually 0-1); t is 0-20; the ratio (a+b+c+t);(1+m) is 0.01-6; wherein x is determined by the oxidation state of the other elements, and wherein the antimony has an average valency higher than +3 and the vanadium has an average valency lower than +5, said second catalyst composition being 0-99 weight percent of a diluent/support and 100-1 weight percent of a catalyst having the components in the proportions indicated by the empirical formula: Bi n Ce p D d E e F f Mo₁₂W g O y formula (2) where D is one or more of Fe, Mn, Pb, Co, Ni, Cu, Sn, P, Cr, Y, Mg, Ca, Sr, Ba and rare earths other than Ce and Sm; E is one or more of Sb, Ge, As, Se, Te and V; F is one or more of an alkali metal, Tl, Ag and Sm and where n is 0.01-24, p is 0.01-24; (n+p) is 0.1-24, d is 0-10, e is 0-10, f is 0-6, and g is 0-8, and y is determined by the oxidation state of the other elements, wherein the weight ratio in said mixture of said first catalyst composition to said second catalyst composition is in the range of 0.001 to 2.5. In an especially useful catalyst of formula (1), m is greater than 1 (often 2-10, more often 3-7). By "particulate mixture" as used herein is meant a mixture of solid particles or subdivided pieces of the first catalyst composition with separate and distinct solid particles of the second catalyst composition. The particles are often of a size used in fluidized bed reactors, say about 40 to 90 microns, but of course larger particles of catalyst can be employed for use in fixed or gravity flowing catalyst beds. In the present process in all its embodiments the ratio of O₂ to NH₃ fed to the reaction zone is usually in the range from 1 to 10 (more often 1-5) and the ratio of inert gaseous diluent to paraffin is usually in the range zero to 5 (more often zero to 3). According to one embodiment of the present invention there is provided an ammoxidation of the type disclosed above which comprises contacting in a reaction zone said paraffin in the vapor phase in admixture with ammonia, molecular oxygen, and optionally an inert gaseous diluent, with an intimate particulate mixture of a first catalyst composition and a second catalyst composition, said feed to the reaction zone containing the components paraffin/NH₃/O₂/inert diluent in the mole rations 8/0.5-1.5/0.1-5/0-5, more usually in the mole ratios 8/0.5-1/0.5-3.5/0-1, said first catalyst composition being 10-99 weight percent of a diluent/support and a 90-1 weight percent of a catalyst having the components in the proportions indicated by the empirical formula: VSb m A a H b C c O x formula (3) where A is one or more of W, Sn, Mo, B, P and Ge and includes at least 0,2 atoms of W; H is one or more of Fe, Co, Ni, Cr, Pb, Mn, Zn, Se, Te, Ga, In and As; C is one or more of an alkali metal, Ca, Sr, Ba and Tl and where m is greater than 1 and up to 20 (usually 2-10, most usually 3-7); a is 0-10; b is 0-20; c is 0-1; a is equal to or less than m; b is equal to or less than m; c is equal to or less than m; wherein x is determined by the oxidation state of the other elements, and wherein the antimony has an average valency higher than +3 and the vanadium has an average valency lower than +5, said second catalyst composition being 0-99 weight percent of a diluent/support and 100-1 weight percent of a catalyst having the components in the proportions indicated by the empirical formula: Bi n Ce p D d E e F f Mo₁₂W g O y formula (2) where D is one or more of Fe, Mn, Pb, Co, Ni, Cu, Sn, P, Mg, Ca, Sr and Ba and rare earths other than Ce and Sm; E is one or more of Sb, Ge, As, Se, Te and V; F is one or more of an alkali metal, Tl, Ag and Sm and where n is 0.01-24, p is 0.01-24; (n+p) is 0.1-24, d is 0-10, e is 0-10, f is 0-6, g is 0-8, and y is determined by the oxidation state of the other elements, wherein the weight ratio in said mixture of said first catalyst composition to said second catalyst composition is in the range of 0.001 to 2.5. The diluent or support for either catalyst composition is a refractory metal oxide or mixture, such as silica, silica-alumina, etc. In the usual practice of the present invention the catalyst support/diluent for the catalyst of formula (1) or (3) is not an oxide of an element named in formula (1) or (3). Further, in the usual practice of the invention the catalyst support/diluent for the catalyst of formula (2) is not an oxide of an element named in formula (2). In the catalyst compositions of the invention the empirical formulas (1), (2) and (3) do not, of course, connote any particular chemical compound, nor indicate whether the elements are present as a mixture of individual oxides or as a complex oxide or oxides, or what separate crystalline phases or solid solutions may be present. Similarly, the designation of certain oxides, such as "silica" or "alumina" or SiO₂ or Al₂O₃, as supports or diluents is merely in accordance with convention in the inorganic oxide catalyst art, and such designations refer to compounds often regarded as supports in the catalyst art. Such designations, however, do not mean that the element involved is actually present as a simplex oxide. Indeed, such elements may at times be present as a complex oxide with one, more than one, or all of the elements in formula (1) or formula (2) or formula (3), which complex oxides form during the precipitation or agglomeration, drying and calcining process for preparing the catalyst composition. According to the present invention the foregoing first catalyst composition is prepared under conditions such that in the final composition the average oxidation state of vanadium is less than 5. One method for preparing the first catalyst composition is by a redox reaction between a compound of trivalent antimony such as Sb₂O₃ and a compound of pentavalent vanadium such as V₂O₅, during which the antimony is oxidized and the vanadium reduced. The foregoing redox reaction was described by Birchall and Sleight ( Inorganic Chem. 15 , 868-70 [1976]) and by Berry et al. ( J. Chem. Soc. Dalton Trans. , 1983 9-12), who affected the reaction by heating a dry mixture of the above reactants at temperatures above 600°C. This product had a tetragonal rutile-type crystalline structure with a unique x-ray diffraction pattern. However, it has been found that the redox reaction can successfully and more conveniently be carried out in an aqueous medium by heating at a temperature of at least 80°C and up to 200°C, for instance, by heating an aqueous dispersion of a V⁵⁺ compound, such as NH₄VO₃ or V₂O₅, with an Sb³⁺ compound, such as by reacting Sb₂O₃ and NH₄VO₃ (or V₂O₅). This step is followed by evaporation, drying and then calcining the product in a molecular oxygen-containing atmosphere, such as air, at from 350 to 700 or 750°C, usually 400 to 650°C. The length of the calcination period may range from 30 minutes to 12 hours, but satisfactory catalyst compositions are usually obtained by calcination at such temperatures for a period of from 1 to 5 hours. At least part of any excess of trivalent antimony compound, such as Sb₂O₃, is usually oxidized to Sb₂O₄ during the calcination in a molecular oxygen-containing atmosphere, such as air. The ingredients of the first catalyst composition other than vanadium and antimony (and of course part of the oxygen) suitably can be incorporated after completion of the foregoing redox reaction. Thus, the additives A, H, C and/or T, if any, can be added in the slurry after the redox reaction, or the solid particles containing the vanadium and antimony values after separation from the aqueous medium can be coated or impregnated in a known manner with such additives at any suitable stage prior to final calcination of the catalyst, by methods generally known in the art, using oxides, hydroxides, acids, salts (particularly organic salts such as acetates), and other compounds of such elements. In formula (1) subscript a usually is at least 0.4 or 0.5. In formula (1) at least 0.2 atoms of W are usually present per atom of V, and the total of W plus Sn atoms ( if any Sn is present) is usually at least 0.4 atoms. Preferred compositions of formula (1) contain at least 0.4 atoms of W per atom of V. Particularly when W is present, it is especially useful to have at least 0.4 atoms of P per atom of V in addition to the W. Especially useful are such compositions wherein said diluent/support comprises 20-100 weight percent alumina and 80 to zero weight percent silica. Especially useful catalysts of formula (1) or (3) description are those in which a is at least 1, wherein A includes at least 1 atom of W. Not only does the catalyst support in the first catalyst composition (formula (1) or (3)) improve mechanical stability of the catalyst, but also the catalytic activity is significantly improved, especially in the case of alumina and silica-alumina. Besides alumina and silica-alumina other supports that can be used are silica, titania, silica-titania, Nb₂O₅, silica-niobia, silica-zirconia, zirconia and magnesia, etc. In the first catalyst composition (formula (1) and (3)), now preferred support materials for not only improving mechanical stability but also for improving the yield of the desired nitriles are selected from silica-alumina and alumina having 20-100, usually 50-100, preferably 60-100 weight percent alumina; silica-titania and titania having 20-100 weight percent titania; silica-zirconia and zirconia having 80-100 weight percent zirconia; and silica-niobia and niobia having 30-100 weight percent niobia (Nb₂O₅). In the preparation of the second catalyst composition of formula (2) the metal oxides can be blended together or can be formed separately and then blended or formed separately or together in situ. Promoter oxides can be incorporated into the bismuth-cerium-molybdenum based catalyst by blending into the gel before calcining or by blending into the oven-dried base catalyst before calcining. A useful manner of incorporating promoter elements is by choosing a water-soluble salt of the promoter element, forming an aqueous solution of the salt, and mixing the solution with a solution or a suspension of the base elements or salts thereof. Optionally, the promoter elements can be incorporated by the use of soluble complex salts or compounds with the desired base elements which upon calcination will yield the desired ratio of the elements in the finished catalyst. The F metals can be introduced into the catalyst as an oxide or as any salt which upon calcination will yield the oxide. Preferred salts are the nitrates which are readily available and easily soluble. Bismuth may be introduced into the catalyst as an oxide or as any salt which upon calcination will yield the oxide. Most preferred are the water-soluble salts which are easily dispersible within the catalyst and which form stable oxides upon heat-treating. The most preferred salt for introducing bismuth is bismuth nitrate. To introduce the iron component into the catalyst one can use any compound of iron which, upon calcination, will result in the oxides. As with the other elements, water soluble salts are preferred for the ease with which they may be uniformly dispersed within the catalyst. Most preferred is ferric nitrate. Cobalt and nickel are similarly introduced. To introduce the molybdenum component any molybdenum oxide such as the dioxide, trioxide, pentoxide or sesquioxide can be used; more preferred is hydrolyzable or decomposable molybdenum salt such as molybdenum halide. A preferred starting material is ammonium heptamolybdate. Other variations in starting materials will suggest themselves to one skilled in the art, particularly when the preferred starting materials mentioned hereinabove are unsuited to the economics of large-scale manufacture. In general, any compounds containing the desired catalyst components may be used provided that they result, upon heating to a temperature within the range disclosed hereinafter, in the oxides of the instant catalyst. These second catalyst compositions are conveniently prepared by slurry techniques wherein an aqueous slurry containing all of the elements in the objective catalyst is produced, the water removed from the aqueous slurry to form a precatalyst precipitate or powder and the precatalyst then heated in the presence of an oxygen-containing gas such as air at elevated temperature to calcine the precatalyst thereby forming the catalyst. Liquids other than water, such as C₁ to C₈ alcohols can also be used to form the precatalyst slurry. In the second catalyst composition the support can be any of the usual supports such as silica, alumina, silica-alumina, titania, zirconia, Nb₂O₅. The catalysts of formula (1) or (3) of the present invention, and used in the process of the invention, are essentially free of uranium. Moreover, in the process of the invention, essentially no sulfur or sulfur compounds, or halogen or halogen compounds, are present in the reaction mixture during the ammoxidation. While particulate catalytic mixtures of formula (1) or (3) and formula (2) catalysts are physical mixtures of separate particles of each catalyst, pellets or other shapes can be pressed from such particulate mixture to form larger particles for fixed bed operations, etc. In the ammoxidation of the present invention, the reaction is carried out in the gas phase by contacting a mixture of the paraffin, ammonia, molecular oxygen, and inert diluent, if any, conveniently in a fixed bed of the catalyst mixture, or a gravity flowing bed, a fluidized bed or a fast transport reactor mode. Examples of inert diluents useful in the reaction are N₂, He, CO₂, H₂O and Ar. The reaction temperature range can vary from 350 to 700°C, but is usually 460 to 520°C. The latter temperature range is especially useful in the case of propane ammoxidation to acrylonitrile. The average contact time can often be from 0.01 to 10 seconds, but is usually from 0.02 to 10 seconds, more usually from 0.1 to 5 seconds. The pressure of the reaction usuaully ranges from 0.13 to 3 bars (2 to 45) psia. Most often, pressure is somewhat above atmospheric. The following examples of the invention are exemplary and should not be taken as in any way limiting. Example 1 A catalyst having the empirical formula 50 wt % VSb₅WO x + 50 wt % Al₂O₃ support was made as follows: In a stirred flask equipped for heating under reflux, 5.4g NH₄VO₃ was dissolved in 150ml hot water. To the hot solution 33.6g Sb₂O₃ was added, and the slurry was boiled under reflux for 16-18 hours overnight. There was ammonia evolution, and the vanadium antimonate mixture turned gray-green. In a separate operation, 59.0g Catapal SB (hydrated alumina) was mixed with 200ml H₂O (cold) + 23.0g acetic acid (10 percent solution) and stirred until the suspension gelled. It took about 3 hours, and the gel was soft, homogeneous, with the consistency of thick cream. Meanwhile, the vanadium antimonate slurry was transferred to a beaker. A solution of 12.5g ammonium meta-tungstate in about 25ml H₂O was then added, followed by the addition, with stirring (magnet) of the alumina gel. After partial evaporation, the mixture became too thick for stirring. It was then transferred to an evaporating dish, and the evaporation, following by drying overnight, was continued in an oven at 110-120°C. The dried material was precalcined at 350°C for 5 hours, screened to 20/35 mesh, then calcined 3 hours at 610°C. Example 2 A catalyst with the empirical formula 50 wt % Bi₃Ce₂Pb₅Mo₁₁W 1.5 O x + 50 wt % SiO₂ was made from the following components: Ammonium heptamolybdate 38.84g Bi(NO₃)₃ · 5H₂O 29.11g Pb(NO₃)₂ 33.12g (NH₄)₂Ce(NO₃)₆ 21.93g (NH₄)₆H₂W₁₂O₄₀ · H₂O(85%WO₃) 8.18g 40%SiO₂ 203.71g Ammonium heptamolybdate was dissolved in ∼200ml warm distilled H₂O. Ammonium metatungstate was then dissolved in this solution. The silica sol (Nalco 2327, 40% SiO₂, ammonium stabilized) was then added to the slurry. In a separate beaker bismuth nitrate was dissolved in ∼50ml 10% nitric acid. Ceric ammonium nitrate was dissolved in this solution. It was warmed and lead nitrate was added. This solution was poured slowly with stirring into the other solution. The pH of the resulting slurry was adjusted to ∼3 by the dropwise addition of concentrated ammonium hydroxide. It was then stirred and heated to remove excess H₂O. It was dried overnight at 120°C. The dried material was denitrified by heating at 290°C for 3 hours and then at 425°C for 3 hours. It was then ground and screened to 20-35 mesh particle size. The catalyst was then calcined at 650°C for 3 hours. Example 3 A catalyst having the composition represented by the empirical formula 50 wt % Bi₄Ce₄Mo₁₀W₂O x and 50 wt % SiO₂ was made as follows: 26.48g of ammonium heptamolybdate were dissolved in about 200ml warm distilled water. 81.8g ammonium metatungstate were then dissolved in this solution. 130.93g silica sol (Nalco 2327, 40% SiO₂, ammonium stabilized) were added. In a separate beaker, 29.11g bismuth nitrate were dissolved in 50 ml of 10% nitric acid. 32.90g ceric ammonium nitrate were then dissolved in this solution. The resulting solution was added slowly with stirring to the molybdate tungstate solution. The pH of the resulting slurry was adjusted to about 3 by the dropwise addition of concentrated ammonium hydroxide. The slurry was then heated and stirred to remove excess water. It was dried overnight at 110°C. The dried material was denitrified by heating at 290°C or 3 hours and then at 425°C for 3 hours. It was ground and screened to between 20-35 mesh particle size. Final calcination was at 650°C for 3 hours. Example 4 A catalyst having the empirical formula 50 wt % VSb 3.5 P 0.5 WO x + 50 wt % Al₂O₃ support was made as follows: In a stirred flask equipped for heating under reflux, 3.81g NH₄VO₃ were dissolved in 90ml hot water. To the hot solution 16.6g Sb₂O₃ were added, and the slurry was boiled under reflux for 16-18 hours overnight. There was ammonia evolution, and the vanadium antimonate mixture turned gray-green. In a separate operation, 35.3g Catapal SB (hydrated alumina) were mixed with 127.2ml H₂O (cold) + 14.1g acetic acid (10 percent solution) and stirred until the suspension gelled. It took about 3 hours, and the gel was soft, homogeneous, with the consistency of thick cream. Meanwhile, the vanadium antimonate slurry was transferred to a beaker. A solution of 8.80g ammonium meta-tungstate in about 20ml H₂O and a solution of 1.77g (NH₄)₂HPO₄ in H₂O were then added, followed by the addition, with stirring (magnet) of the alumina gel. After partial evaporation, the mixture became too thick for stirring. It was then transferred to an evaporating dish, and the evaporation, following by drying overnight, was continued in an oven at 110-120°C. The dried material was precalcined at 350°C for 5 hours, screened to 20/35 mesh, then calcined 3 hours at 610°C. Example 5 A catalyst having the empirical formula 50 wt % VSb₅K 0.2 WO x + 50 wt % Al₂O₃ support was made as follows: In a stirred flask equipped for heating under reflux, 3.20g NH₄VO₃ were dissolved in 90ml hot water. To the hot solution 19.90g Sb₂O₃ were added, and the slurry was boiled under reflux for 16-18 hours overnight. There was ammonia evolution, and the vanadium antimonate mixture turned gray-green. In a separate operation, 35.3g Catapal SB (hydrated alumina) were mixed with 127.2ml H₂O (cold) + 14.1g acetic acid (10 percent solution) and 3.8ml of 0.1g/ml K₂CO₃ solution and stirred until the suspension gelled. It took about 3 hours, and the gel was soft, homogeneous, with the consistency of thick cream. Meanwhile, the vanadium antimonate slurry was transferred to a beaker. A solution of 7.36g ammonium meta-tungstate in about 15ml H₂O was then added, followed by the addition, with stirring (magnet) of the alumina gel. After partial evaporation, the mixture became too thick for stirring. It was then transferred to an evaporating dish, and the evaporation, following by drying overnight, was continued in an oven at 110-120°C. The dried material was precalcined at 350°C for 5 hours, screened to 20/35 mesh, then calcined 3 hours at 610°C. Example 6 A catalyst having the empirical formula 50 wt % VSb₅Pb 0.5 WO x + 50 wt % Al₂O₃ support was made as follows: In a stirred flask equipped for heating under reflux, 2.94g NH₄VO₃ were dissolved in 90ml hot water. To the hot solution 18.30g Sb₂O₃ were added, and the slurry was boiled under reflux for 16-18 hours overnight. There was ammonia evolution, and the vanadium antimonate mixture turned gray-green. In a separate operation, 35.3g Catapal SB (hydrated alumina) were mixed with 127.2ml H₂O (cold) + 14.1g acetic acid (10 percent solution) and stirred until the suspension gelled. It took about 3 hours, and the gel was soft, homogeneous, with the consistency of thick cream. Meanwhile, the vanadium antimonate slurry was transferred to a beaker. A solution of 6.77g ammonium meta-tungstate in about 15ml H₂O and a solution of 4.76g Pb(OAc)₂·3H₂O in H₂O were then added, followed by the addition, with stirring (magnet) of the alumina gel. After partial evaporation, the mixture became too thick for stirring. It was then transferred to an evaporating dish, and the evaporation, following by drying overnight, was continued in an oven at 110-120°C. The dried material was precalcined at 350°C for 5 hours, screened to 20/35 mesh, then calcined 3 hours at 610°C. Example 7 A catalyst having the empirical formula 47 wt % VSb₅WO x + 50 wt % Al₂O₃/3 wt % Nb₂O₅ support was made as follows: In a stirred flask equipped for heating under reflux, 5.4g NH₄VO₃ were dissolved in 150ml hot water. To the hot solution 33.6g Sb₂O₃ were added, and the slurry was boiled under reflux for 16-18 hours overnight. There was ammonia evolution, and the vanadium antimonate mixture turned gray-green. Meanwhile, the vanadium antimonate slurry was transferred to a beaker. A solution of 12.5g ammonium meta-tungstate in about 25ml H₂O was then added. 7.34g Nb(OEt)₅ was added dropwise with good agitation. After evaporation, the material was dried overnight in an oven at 110-120°C. The dried material was ground and thoroughly mixed with 53.5g Catapal SB. The mixture was kneaded to a paste with a solution of 6ml glacial acetic acid in 57ml H₂O. Additional H₂O had to be added. The paste was dried again at 110-120°C overnight. This dried material was precalcined at 350°C for 2.5 hours, and at 420°C for 2.5 hours screened to 20/35 mesh, then calcined 3 hours at 610°C. Example 8 A catalyst was made having the empirical composition, 50 wt % Bi 6.8 Ce 1.2 Mo₁₂O x + 50 wt % SiO₂, as follows: 41.23g of bismuth nitrate were dissolved in 50ml of dilute (10%) nitric acid. 8.22g of ceric ammonium nitrate were dissolved in the bismuth nitrate solution. In a separate step 26.48g of ammonium heptamolybdate were dissolved in 50ml of water. To this solution were added 109.64g of 40 wt% silica sol, ammonium stabilized. The nitrate solution was then slowly added to this mixture with constant stirring with a magnetic stirrer. The resulting mixture was heated to approximately 80°C and evaporated to dryness with constant stirring. The resulting mass was further dried in an oven at about 120°C for 16 hours. The dried material was heat treated in air at 290°C for 3 hours, 425°C for 3 hours, and finally at 550°C for 16 hours. Example 9 A catalyst was made having the empirical composition, 80 wt% Bi₂Ce₆Mo₁₂O x + 20 wt% SiO₂, as follows: 19.40g bismuth nitrate were dissolved in 50ml of dilute (10%) nitric acid. 65.79g of ceric ammonium nitrate were dissolved in the bismuth nitrate solution. In a separate step 42.38g of ammonium heptamolybdate were dissolved in about 100ml of water. To this solution were added 39.72g of 40 wt% silica sol, ammonium stabilized. The nitrate solution was then slowly added to this mixture with constant stirring. The pH of the mixture was adjusted to about 3.0 by the dropwise addition of a concentrated ammonium hydroxide solution. The mixture was refluxed for 3 hours. Additional water was added to the slurry as necessary to keep the mixture stirring. The slurry was then evaporated to dryness and the resulting mass was further dried in an oven at about 120°C for 16 hours. The dried material was heat treated in air at 290°C for 3 hours, 425°C for 3 hours, and finally at 550°C for 16 hours. Example 10 A catalyst was made having the empirical composition, 80 wt% K 0.05 Cs 0.02 Bi₄Ce₄Mo 12.03 O x + 20 wt% SiO₂ as follows: 38.81g of bismuth nitrate were dissolved in 50ml of dilute (10%) nitric acid. 43.86g of ceric ammonium nitrate were dissolved in the bismuth nitrate solution. To this solution were added 1.0g of a 10 wt% KNO₃ solution and 0.78g of a 10 wt% CsNO₃ solution. In a separate step 42.48g of ammonium heptamolybdate were dissolved in about 100 ml of water. To this solution were added 41.56g of 40 wt% silica sol, ammonium stabilized. The nitrate solution was then slowly added to this mixture with constant stirring. The pH of the mixture was adjusted to about 3.0 by the dropwise addition of a concentrated ammonium hydroxide solution. The mixture was refluxed for 3 hours. Additional water was added to the slurry as necessary to keep the mixture stirring. The slurry was then evaporated to dryness and the resulting mass was further dried in an oven at about 120°C for 16 hours. The dried material was heat treated in air at 290°C for 3 hours, 425°C for 3 hours, and finally at 550°C for 16 hours. Example 11 A catalyst was made having the empirical composition, 80 wt% Bi₄Ce₄Mo₁₀W₂O x + 20 wt% SiO₂, as follows: 38.81g of bismuth nitrate were dissolved in 50ml of dilute (10%) nitric acid. 43.86g of ceric ammonium nitrate were dissolved in the bismuth nitrate solution. In a separate step 35.31g of ammonium heptamolybdate and 9.86g of ammonium metatungstate (85 wt% WO₃ equivalent) were dissolved in about 100 ml of water. To this solution were added 43.64g of 40% silica sol, ammonium stabilized. The nitrate solution was then slowly added to this mixture with constant stirring. The pH of the mixture was adjusted to about 3.0 by the dropwise addition of a concentrated ammonium hydroxide solution. The mixture was refluxed for 3 hours. Additional water was added to the slurry as necessary to keep the mixture stirring. The slurry was then evaporated to dryness and the resulting mass was further dried in an oven at about 120°C for 16 hours. The dried material was heat treated in air at 290°C for 3 hours, 425°C for 3 hours, and finally at 550°C for 16 hours. Example 12 A catalyst was made having the empirical composition, 80 wt% Tl 0.03 Bi₄Ce₄Mo₁₂O x + 20 wt% SiO₂ as follows: 38.81g of bismuth nitrate were dissolved in 50ml of dilute (10%) nitric acid. 43.86g of ceric ammonium nitrate and 0.16g of thallous nitrate were dissolved in the bismuth nitrate solution. In a separate step 42.38g of ammonium heptamolybdate were dissolved in about 100ml of water. To this solution were added 41.53g of 40 wt% silica sol, ammonium stabilized. The nitrate solution was then slowly added to this mixture with constant stirring. The pH of the mixture was adjusted to about 3.0 by the dropwise addition of a concentrated ammonium hydroxide solution. The mixture was refluxed for 3 hours. Additional water was added to the slurry as necessary to keep the mixture stirring. The slurry was then evaporated to dryness and the resulting mass was further dried in an oven at about 120°C for 16 hours. The dried material was heat treated in air at 290°C for 3 hours, 425°C for 3 hours, and finally at 550°C for 16 hours. Example 13 A catalyst was made having the empirical composition, 80 wt% Cs 0.02 Bi₄Ce₄Mo 12.01 O x + 20 wt% SiO₂ as follows: 38.81g of bismuth nitrate were dissolved in 50ml of dilute (10%.) HNO₃. 43.86 grams of ceric ammonium nitrate were dissolved in the bismuth nitrate solution along with 0.40g of a 10 wt% CsNO₃ solution. In a separate step 42.41g of ammonium heptamolybdate were dissolved in about 100ml of water. To this solution were added 41.49g of 40 wt% silica sol, ammonium stabilized. The nitrate solution was then slowly added to this mixture with constant stirring. The pH of the mixture was adjusted to about 3.0 by the dropwise addition of a concentrated ammonium hydroxide solution. The mixture was refluxed for 3 hours. Additional water was added to the slurry as necessary to keep the mixture stirring. The slurry was then evaporated to dryness and the resulting mass was further dried in an oven at about 120°C for 16 hours. The dried material was heat treated in air at 290°C for 3 hours, 425°C for 3 hours, and finally at 550°C for 16 hours. Example 14 A catalyst was made having the empirical composition, 80 wt% Bi₇Ce₁Mo₁₀W₂O x + 20 wt% SiO₂ as follows: 67.91g of bismuth nitrate were dissolved 50ml of dilute (10%) nitric acid. 10.96g of ceric ammonium nitrate were dissolved in the bismuth nitrate solution. In a separate step 35.31g of ammonium heptamolybdate and 10.91g of ammonium metatungstate (85 wt% WO₃ equivalent) were dissolved in about 100ml of water. To this solution were added 46.23g of 40 wt% silica sol, ammonium stabilized. The nitrate solution was then slowly added to this mixture with constant stirring. The pH of the mixture was adjusted to about 3.0 by the dropwise addition of a concentrated ammonium hydroxide solution. The mixture was refluxed for 3 hours. Additional water was added to the slurry as necessary to keep the mixture stirring. The slurry was then evaporated to dryness and the resulting mass was further dried in an oven at about 120°C for 16 hours. The dried material was heat treated in air at 290°C for 3 hours, 425°C for 3 hours, and finally at 550°C for 16 hours. Example 15 A catalyst was made having the empirical composition, 80 wt% Cr₂Ce₂Bi₄Mo₁₂O x + 20 wt% SiO₂ as follows: 38.81g of bismuth nitrate were dissolved in 50ml of dilute (10%) nitric acid. 21.93g of ceric ammonium nitrate and 16.01g of chromium nitrate were dissolved in the bismuth nitrate solution. In a separate step 42.38g of ammonium heptamolybdate were dissolved in about 100 ml of water. To this solution were added 39.24g of 40 wt% silica sol, ammonium stabilized. The nitrate solution was then slowly added to this mixture with constant stirring. The pH of the mixture was adjusted to about 3.0 by the dropwise addition of a concentrated ammonium hydroxide solution. The mixture was refluxed for 3 hours. Additional water was added to the slurry as necessary to keep the mixture stirring. The slurry was then evaporated to dryness and the resulting mass was further dried in an oven at about 120°C for 16 hours. The dried material was heat treated in air at 290°C for 3 hours, 425°C for 3 hours, and finally at 550°C for 16 hours. Example 16 A catalyst was made having the empirical composition, 80 wt% Te₂Ce₂Bi₄Mo₁₂O x + 20 wt% SiO₂, as follows: 38.81g of bismuth nitrate were dissolved in 50ml of dilute (10%) nitric acid. 21.93g of ceric ammonium nitrate were dissolved in the bismuth nitrate solution. In a separate step 42.38g of ammonium heptamolybdate were dissolved in about 150ml of water. 9.19g of H₂TeO₄·H₂O were added to the solution along with 100ml of water. Enough ammonium hydroxide was added to get all the telluric acid into solution. To this solution were added 41.33g of 40 wt% silica sol, ammonium stabilized. The nitrate solution was then slowly added to this mixture with constant stirring. The pH of the mixture was adjusted to about 3.0 by the dropwise addition of a concentrated ammonium hydroxide solution. The mixture was refluxed for 3 hours. Additional water was added to the slurry as necessary to keep the mixture stirring. The slurry was then evaporated to dryness and the resulting mass was further dried in an oven at about 120°C for 16 hours. The dried material was heat treated in air at 290°C for 3 hours, 425°C for 3 hours, and finally at 550°C for 16 hours. Example 17 A catalyst was made having the empirical composition, 50 wt% Bi₄Ce₄Sb₁Mo₁OW₂O x + 50 wt% SiO₂, as follows: 29.11g of bismuth nitrate were dissolved in 50ml of dilute (10%) nitric acid. 32.89g of ceric ammonium nitrate were dissolved in the bismuth nitrate solution. In a separate step 26.48g of ammonium heptamolybdate and 8.18g of ammonium metatungstate (85 wt% WO₃ equivalent) were dissolved in about 100 ml of water. To this solution were added 2.19g of antimony trioxide followed by 39.24g of 40 wt% silica sol (Nalco 2327). The nitrate solution was then slowly added to this mixture with constant stirring. The pH of the mixture was adjusted to about 3.0 by the dropwise addition of a concentrated ammonium hydroxide solution. The slurry was then evaporated to dryness and the resulting mass was further dried in an oven at about 120°C for 16 hours. The dried material was heat treated in air at 290°C for 3 hours, 425°C for 3 hours, and finally at 650°C for 3 hours. Example 18 A catalyst was made having the empirical composition, 80 wt% Bi₄Ce₄Fe 0.05 Sb₁Mo₁₀W₂O x + 20 wt% SiO₂, as follows: 38.81g of bismuth nitrate were dissolved in 50ml of dilute (10%) nitric acid. 43.86g of ceric ammonium nitrate and 4.04g of ferric nitrate were dissolved in the bismuth nitrate solution. In a separate step 35.31g of ammonium heptamolybdate and 10.91g of ammonium metatungstate (85 wt% WO₃ equivalent) were dissolved in about 100 ml of water. To this solution were added 2.92g of antimony trioxide followed by 45.97g of 40 wt% silica sol (Nalco 2327). The nitrate solution was then slowly added to this mixture with constant stirring. The pH of the mixture was adjusted to about 3.0 by the dropwise addition of a concentrated ammonium hydroxide solution. The slurry was then evaporated to dryness and the resulting mass was further dried in an oven at about 120°C for 16 hours. The dried material was heat treated in air at 290°C for 3 hours, 425°C for 3 hours, and finally at 550°C for 16 hours. Example 19 A catalyst was made having the empirical composition, 80 wt% Bi₄Ce₄Mn₁Sb₁Mo₁₀W₂O x + 20 wt% SiO₂, as follows: 38.81g of bismuth nitrate were dissolved in 50ml of dilute (10%) nitric acid. 43.86g of ceric ammonium nitrate and 6.99g of a 51.2 wt% manganous nitrate solution were dissolved in the bismuth nitrate solution. In a separate step 35.31g of ammonium heptamolybdate and 10.91g of ammonium metatungstate (85 wt% WO₃ equivalent) were dissolved in about 100 ml of water. To this solution were added 2.92g of antimony trioxide followed by 46.35g of 40 wt% silica sol (Nalco 2327). The nitrate solution was then slowly added to this mixture with constant stirring. The pH of the mixture was adjusted to about 3.0 by the dropwise addition of a concentrated ammonium hydroxide solution. The slurry was then evaporated to dryness and the resulting mass was further dried in an oven at about 120°C for 16 hours. The dried material was heat treated in air at 290°C for 3 hours, 425°C for 3 hours, and finally at 550°C for 16 hours. Example 20 A catalyst was made having the empirical composition, 80 wt% Bi₄Ce₄V 0.5 Mg 0.5 Sb₁Mo₁₀W₂O x + 20 wt% SiO₂, as follows: 38.81g of bismuth nitrate were dissolved in 50ml of dilute (10%) nitric acid. 43.86g of ceric ammonium and 2.56g of magnesium nitrate were dissolved in the bismuth nitrate solution. In a separate step 35.31g of ammonium heptamolybdate, 10.91g of ammonium metatungstate (85 wt% WO₃ equivalent), and 1.17g of ammonium metavanadate were dissolved in about 150 ml of water along with sufficient ammonium hydroxide to effect complete dissolution. To this solution were added 2.92g of antimony trioxide followed by 46.30g of 40 wt% silica sol (Nalco 2327). The nitrate solution was then slowly added to this mixture with constant stirring. The pH of the mixture was adjusted to about 3.0 by the dropwise addition of a concentrated ammonium hydroxide solution. The slurry was then evaporated to dryness and the resulting mass was further dried in an oven at about 120°C for 16 hours. The dried material was heat treated in air at 290°C for 3 hours, 425°C for 3 hours, and finally at 550°C for 16 hours. Example 21 A catalyst was made having the empirical composition, 50 wt% Bi₄Ce₄Sb₁Mo₈W₂O x + 50 wt% SiO₂, as follows: 29.19g of bismuth nitrate were dissolved in 50ml of dilute (10%) nitric acid. 32.89g of ceric ammonium nitrate were dissolved in the bismuth nitrate solution. In a separate step 21.19g of ammonium heptamolybdate and 8.18g of ammonium metatungstate (85 wt% WO₃ equivalent) were dissolved in about 150 ml of water along with sufficient ammonium hydroxide to effect complete dissolution. To this solution were added 2.19g of antimony trioxide followed by 125.60g of 40 wt% silica sol (Nalco 2327). The nitrate solution was then slowly added to this mixture with constant stirring. The pH of the mixture was adjusted to about 3.0 by the dropwise addition of a concentrated ammonium hydroxide solution. The slurry was then evaporated to dryness and the resulting mass was further dried in an oven at about 120°C for 16 hours. The dried material was heat treated in air at 290°C for 3 hours, 425°C for 3 hours, and finally at 650°C for 3 hours. Example 22 A catalyst was made having the empirical composition, 80 wt% Bi₃Ce₃Pb₃Sb₁Mo₁₀W₂O x + 20 wt% SiO₂, as follows: 29.11g of bismuth nitrate were dissolved in 50ml of dilute (10%) nitric acid. 32.89g of ceric ammonium nitrate and 19.87g of lead nitrate were dissolved in the bismuth nitrate solution. In a separate step 35.31g of ammonium heptamolybdate and 10.91g of ammonium metatungstate (85 wt% WO₃ equivalent) were dissolved in about 100ml of water along with sufficient ammonium hydroxide to effect complete dissolution. To this solution were added 2.92g of antimony trioxide followed by 48.87g of 40 wt% silica sol (Nalco 2327). The nitrate solution was then slowly added to this mixture with constant stirring. The pH of the mixture was adjusted to about 3.0 by the dropwise addition of a concentrated ammonium hydroxide solution. The slurry was then evaporated to dryness and the resulting mass was further dried in an oven at about 120°C for 16 hours. The dried material was heat treated in air at 290°C for 3 hours, 425°C for 3 hours, and finally at 550°C for 16 hours. Example 23 A catalyst was made having the empirical composition, 80 wt% Bi 3.5 Ce 3.5 Cr₁Mo₁₂O x + 20 wt% SiO₂, as follows: 29.11g of bismuth nitrate were dissolved in 50ml of dilute (10%) nitric acid. 32.89g of ceric ammonium nitrate and 16.01g of chromium nitrate were dissolved in the bismuth nitrate solution. In a separate step 42.37g of ammonium heptamolybdate were dissolved in about 100 ml of water. To this solution were added 38.38g of 40 wt% silica sol (Nalco 2327). The nitrate solution was then slowly added to this mixture with constant stirring. The pH of the mixture was adjusted to about 3.0 by the dropwise addition of a concentrated ammonium hydroxide solution. The slurry was then evaporated to dryness and the resulting mass was further dried in an oven at about 120°C for 16 hours. The dried material was heat treated in air at 290°C for 3 hours, 425°C for 3 hours, and finally at 550°C for 16 hours. Example 24 A catalyst was made have the empirical composition, 80 wt% La₂Ce₂Bi₄Mo₁₂O x + 20 wt% SiO₂, as follows: 38.81g of bismuth nitrate were dissolved in 50ml of dilute (10%) nitric acid. 21.93g of ceric ammonium nitrate and 15.88g of lanthanum nitrate were dissolved in the bismuth nitrate solution. In a separate step 42.38g of anmonium heptamolybdate were dissolved in about 100ml of water. To this solution were added 41.41g of 40 wt% silica sol (Nalco 2327). The nitrate solution was then slowly added to this mixture with constant stirring. The pH of the mixture was adjusted to about 3.0 by the dropwise addition of a concentrated ammonium hydroxide solution. The slurry was then evaporated to dryness and the resulting mass was further dried in an oven at about 120°C for 16 hours. The dried material was heat treated in air at 290°C for 3 hours, 425°C for 3 hours, and finally at 550°C for 16 hours. Example 25 A catalyst was made having the empirical composition, 80 wt% Y₂Ce₂Bi₄Mo₁₂O x + 20 wt% SiO₂, as follows: 38.81g of bismuth nitrate were dissolved in 50ml of dilute (10%) nitric acid. 21.93g of ceric ammonium nitrate and 14.60g of yttrium nitrate were dissolved in the bismuth nitrate solution. In a separate step 42.38g of ammonium heptamolybdate were dissolved in about 100ml of water. To this solution were added 40.17g of 40 wt% silica sol (Nalco 2327). The nitrate solution was then slowly added to this mixture with constant stirring. The pH of the mixture was adjusted to about 3.0 by the dropwise addition of a concentrated ammonium hydroxide solution. The mixture was refluxed for 3 hours. Additional water was added to the slurry as necessary to keep the mixture stirring. The slurry was then evaporated to dryness and the resulting mass was further dried in an oven at about 120°C for 16 hours. The dried material was heat treated in air at 290°C for 3 hours, 425°C for 3 hours, and finally at 550°C for 16 hours. Example 26 A catalyst was made having the empirical composition, 80 wt% K 0.1 Pr₂Ce₂Bi₄Mo 12.05 O x + 20 wt% SiO₂, as follows: 38.81g of bismuth nitrate were dissolved in 50ml of dilute (10%) nitric acid. 21.93g of ceric ammonium nitrate and 16.68g of praseodymium nitrate were dissolved in the bismuth nitrate solution. To this solution were added 2.00g of a 10 wt% solution of KNO₃. In a separate step 42.55g of ammonium heptamolybdate were dissolved in about 100ml of water. To this solution were added 41.61g of 40 wt% silica sol (Nalco 2327). The nitrate solution was then slowly added to this mixture with constant stirring. The pH of the mixture was adjusted to about 3.0 by the dropwise addition of a concentrated ammonium hydroxide solution. The mixture was refluxed for 3 hours. Additional water was added to the slurry as necessary to keep the mixture stirring. The slurry was then evaporated to dryness and the resulting mass was further dried in an oven at about 120°C for 16 hours. The dried material was heat treated in air at 290°C for 3 hours, 425°C for 3 hours, and finally at 550°C for 16 hours. Example 27 A catalyst was made having the empirical composition, 80 wt% K 0.1 Nd₂Ce₂Bi₄Mo 12.05 O x + 20 wt% SiO₂, as follows: 38.81g of bismuth nitrate were dissolved in 50ml of dilute (10%) nitric acid. 21.93g of ceric ammonium nitrate and 17.53g of neodymium nitrate were dissolved in the bismuth nitrate solution. To this solution were added 2.02g of a 10 wt% solution of KNO₃. In a separate step 42.55g of ammonium heptamolybdate were dissolved in about 100ml of water. To this solution were added 41.70g of 40 wt% silica sol (Nalco 2327). The nitrate solution was then slowly added to this mixture with constant stirring. The pH of the mixture was adjusted to about 3.0 by the dropwise addition of a concentrated ammonium hydroxide solution. The mixture was refluxed for 3 hours. Additional water was added to the slurry as necessary to keep the mixture stirring. The slurry was then evaporated to dryness and the resulting mass was further dried in an oven at about 120°C for 16 hours. The dried material was heat treated in air at 290°C for 3 hours, 425°C for 3 hours, and finally at 550°C for 16 hours. Example 28 A catalyst was made having the empirical composition, 80 wt% K 0.01 Di₂Ce₂Bi₄Mo 12.03 O x + 20 wt% SiO₂, as follows: 38.81g of bismuth nitrate were dissolved in 50ml of dilute (10%) nitric acid. 21.93g of ceric ammonium nitrate and 15.88g of didymium nitrate were dissolved in the bismuth nitrate solution. To this solution were added 2.00g of a 10 wt% solution of KNO₃. In a separate step 42.55g of ammonium heptamolybdate were dissolved in about 100ml of water. To this solution were added 41.56g of 40 wt% silica sol (Nalco 2327). The nitrate solution was then slowly added to this mixture with constant stirring. The pH of the mixture was adjusted to about 3.0 by the dropwise addition of a concentrated ammonium hydroxide solution. The mixture was refluxed for 3 hours. Additional water was added to the slurry as necessary to keep the mixture stirring. The slurry was then evaporated to dryness and the resulting mass was further dried in an oven at about 120°C for 16 hours. The dried material was heat treated in air at 290°C for 3 hours, 425°C for 3 hours, and finally at 550°C for 16 hours. In the ammoxidation runs of the following examples, the catalyst, or the mixture of catalysts, is in a tubular 3/8 inch I.D. stainless steel fixed bed reactor. When a mixture of particulate catalysts is used, as in the invention examples, the desired weight of each of the two catalyst compositions is put in a vial and shaken until uniformly dispersed before placing the desired amount of the catalyst mixture in the reaction tube. The reactor is equipped with a preheat leg immersed in a temperature controlled molten salt bath. The feed is fed to the catalyst for one hour before the runs are started; the runs of each example last 30 minutes. Example 29 A catalyst having the empirical composition 50 wt % VSbPWO x - 50 wt % Al₂O₃ was made as follows: Ammonium meta-vanadate (5.48 g) and ammonium meta-tungstate (12.64g) were dissolved in ∼ 100 cc of hot water. 85% phosphoric acid (5.34g) was then added to the above solution along with an additional 20-30cc of water, turning the solution from yellow to a deep burgundy red. While rapidly stirring the red solution from above, antimony trioxode (6.75g) was added, resulting in an initial red/orange slurry. This slurry was covered and allowed to "reflux" for one hour after which the color changed to a dark blue/green. In a separate beaker, Catapal SB Al₂O₃ (29.41g = 25.0g Al₂O₃) was slurried in 100 cc H₂O and peptized with glacial acetic acid (4.2g) to form a sol-like dispersed alumina. After aging for 1 hour, this dispersion was slowly added to the blue/green slurry from above along with enough water to prevent the slurry from gelling up ( ∼ 100 cc). The resulting blue/green slurry was then evaporated to near dryness on a hot plate, and the thick bluish paste obtained was further dried at 110°C for ∼ 16 hrs. A heat treatment of 350°C for 5 hours was carried out on the dried catalyst precursor, followed by crushing and screening to +20-35 mesh particles. A portion of the sieved materials was then subjected to a final calcination of 610°C for 3 hours. Example 30 A catalyst having the empirical composition 50 wt % VSb 0.5 PWO x -50 wt % Al₂O₃ was made exactly as in Example 29 but using the following amounts of the batch materials: NH₄VO₃ 7.16g "WO₃" 16.70g 85% H₃PO₄ 7.06g Sb₂O₃ 0.89g Al₂O₃ (catapal SB alumina) 29.41g Example 31 A catalyst having the empircal composition 25 wt% VPWO x - 75 wt% Al₂O₃ was made as in Example 29, but using the amounts of the batch materials shown below, including oxalic acid, which was added to the vanadium, phosphorus and tungsten containing solution to form a solution also containing antimony (instead of the slurry of Example 1). NH₄VO₃ 3.75g "WO₃" 8.66g 85% H₃PO₄ 3.66g oxalic acid 8.0g Al₂O₃ (Catapal SB) 44.12g Example 32 A catalyst having the empirical composition 50 wt% Bi₄Ce₄Mo₁₀W₂O x + 50 wt% SiO₂ was made as follows: 1765.65g of (NH₄)₆Mo₇O₂₄ · 4 H₂O were dissolved in 2000 ml warm water. 545.7g (NH₄)₆H₂W₁₂O₄₀ · H₂O --- 85% WO₃ --- were dissolved with the addition more H₂O, to make a solution of 4750 ml. A 40 wt % SiO₂ sol (NH₃ stabilized) was added in the amount of 8728.75g. In a separate beaker, 1940.4g Bi(NO₃)₃ · 5 H₂O were dissolved in a mixture of 47.5 ml conc. HNO₃ and 250 ml H₂O. 2193.04g (NH₄)₂Ce(NO₃)₆ were then dissolved in the solution. The resulting solution was added slowly with stirring to the molybdate tungstate silica solution. The pH of the resulting slurry was adjusted to about 3 by the addition of about 1500 ml of concentrated ammonium hydroxide. A portion of this slurry was then heated and stirred to remove excess water. It was dried overnight at 110°C. The dried material was denitrified by heating at 290°C or 3 hours and then at 425°C for 3 hours. It was ground and screened to between 20-35 mesh particle size. Final calcinationw as at 650°C for 3 hours. Example 33 In this example the gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was a mixture of the catalyst of Example 1 and the catalyst of Example 3 in the weight ratio of the former to the latter of 1.9. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 500°C and the molar feed ratios were 8 propane/1.1 NH₃/2.1 O₂/1 H₂O. The contact time was 0.4 seconds. Analysis of the reactor effluent showed that propane conversion was 11.9 percent; yield and selectivity of propane to acrylonitrile were 3.1 and 26.1, respectively; yield and selectivity to HCN were 0.6 and 5.1, respectively; yield and selectivity to propylene were 5.3 and 44.7, respectively. Comparative Example A In this example the gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 500°C and the molar feed ratios were 8 propane/1.1 NH₃/2.1 O₂/1 H₂O. The catalyst was the catalyst of Example 1 alone. The contact time was 0.2 seconds. Analysis of the reactor effluent showed that propane conversion was 13.5 percent; yield and selectivity of propane to acrylonitrile were 1.7 and 12.7, respectively; yield and selectivity to HCN were 0.8 and 5.7, respectively; yield and selectivity to propylene were 7.8 and 58.1, respectively. Even though Example 33 gave a somewhat lower conversion of propane, note that when compared to this example the yield and selectivity to acrylonitrile were higher and the yield and selectivity to propylene were desirably lower. Example 34 In this example the gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was a mixture of the catalyst of Example 1 and the catalyst of Example 3 in the weight ratio of the former to the latter of 0.95. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 500°C and the molar feed ratios were 8 propane/1.1 NH₃/2.1 O₂/1 H₂O. The contact time was 0.6 seconds. Analysis of the reactor effluent showed that propane conversion was 10.9 percent; yield and selectivity of propane to acrylonitrile were 3.6 and 33.2, respectively; yield and selectivity to HCN were 0.6 and 5.2, respectively; yield and selectivity to propylene were 4.2 and 38.6, respectively. Example 35 In this example the gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was a mixture of the catalyst of Example 1 and the catalyst of Example 3 in the weight ratio of the former to the latter of 0.48. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 500°C and the molar feed ratios were 8 propane/1.1 NH₃/2.1 O₂/1 H₂O. The contact time was 1.0 seconds. Analysis of the reactor effluent showed that propane conversion was 9.9 percent; yield and selectivity of propane to acrylonitrile were 3.6 and 36.8, respectively; yield and selectivity to HCN were 0.4 and 4.3 respectively; yield and selectivity to propylene were 3.3 and 33.3, respectively. Example 36 In this example the gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was a mixture of the catalyst of Example 1 and the catalyst of Example 3 in the weight ratio of the former to the latter of 0.48. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 500°C and the molar feed ratios were 8 propane/1.1 NH₃/3.0 O₂/1.1 H₂O. The contact time was 1.0 seconds. Analysis of the reactor effluent showed that propane conversion was 13.5 percent; yield and selectivity of propane to acrylonitrile were 5.4 and 39.7, respectively; yield and selectivity to HCN were 0.6 and 4.6, respectively; yield and selectivity to propylene were 3.0 and 22.7, respectively. This example shows the favorable effect, compared to Example 35, of an increased oxygen to propane ratio. Comparative Example B In this example the gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was a mixture of the catalyst of Example 1 and a prior art catalyst for the ammoxidation of propylene having the composition 50% Cs 0.05 K 0.1 Ni 2.5 Co 4.5 MnFe₂BiCr 0.5 Mo 13.2 O x + 50% SiO₂ support. The weight ratio of the former to the latter was 0.11. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 500°C and the molar feed ratios were 8 propane/1.1 NH₃/2.1 O₂/1 H₂O. The contact time was 2.0 seconds. Analysis of the reactor effluent showed that propane conversion was 6.7 percent; yield and selectivity of propane to acrylonitrile were 0.9 and 13.8, respectively; yield and selectivity to HCN were 0.1 and 1.0, respectively; yield and selectivity to propylene were 2.6 and 39.2, respectively. The run shows the effect of using a co-catalyst outside of the invention. Example 37 In this example the gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was a mixture of tile catalyst of Example 1 and the catalyst of Example 3 in the weight ratio of the former to the latter of 0.21. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 500°C and the molar feed ratios were 8 propane/1.1 NH₃/2.1 O₂/1 H₂O. The contact time was 2.0 seconds. Analysis of the reactor effluent showed that propane conversion was 9.2 percent; yield and selectivity of propane to acrylonitrile were 4.8 and 52.1, respectively; yield and selectivity to HCN were 0.3 and 3.6, respectively; yield and selectivity to propylene were 1.6 and 16.9, respectively. Example 38 In this example the gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was a mixture of the catalyst of Example 1 and the catalyst of Example 3 in the weight ratio of the former to the latter of 0.21. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 500°C and the molar feed ratios were 8 propane/1.1 NB₃/2.1 O₂/1 H₂O. The contact time was 2.2 seconds. Analysis of the reactor effluent showed that propane conversion was 8.6 percent; yield and selectivity of propane to acrylonitrile were 4.4 and 51.1, respectively; yield and selectivity to HCN were 0.4 and 4.0, respectively; yield and selectivity to propylene were 1.6 and 18.5, respectively. Example 39 In this example the gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was a mixture of the catalyst of Example 1 and the catalyst of Example 3 in the weight ratio of the former to the latter of 0.10. Water was introduced through a septum at the top of the preheat leg, using a syringe pimp. The reaction temperature was 500°C and the molar feed ratios were 8 propane/1.1 NH₃/2.1 O₂/1 H₂O. The contact time was 4.0 seconds. Analysis of the reactor effluent showed that propane conversion was 8.3 percent; yield and selectivity of propane to acrylonitrile were 4.9 and 59.2, respectively; yield and selectivity to HCN were 0.3 and 3.1, respectively; yield and selectivity to propylene were 0.8 and 9.2, respectively. Example 40 In this example the gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was the catalyst of Example 1 and the catalyst of Example 3 in the weight ratio of the former to the latter of 0.10. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 500°C and the molar feed ratios were 8 propane/1.1 NH₃/2.1 O₂/1 H₂O. The contact time was 2.4 seconds. Analysis of the reactor effluent showed that propane conversion was 7.3 percent; yield and selectivity of propane to acrylonitrile were 4.3 and 58.2, respectively; yield and selectivity to HCN were 0.4 and 4.9, respectively; yield and selectivity to propylene were 0.5 and 6.8, respectively. Compared with Example 31, this example shows that a shorter contact time sacrifices little in selectivity to acrylonitrile and results in less propylene per mole of converted propane. Comparative Example C In this example the gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was the catalyst of Example 3 above. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 500°C and the molar feed ratios were 8 propane/1.1 NH₃/2.1 O₂/1 H₂O. The contact time was 3.8 seconds. Analysis of the reactor effluent showed that propane conversion was only 2.8 percent; yield and selectivity of propane to acrylonitrile were 1.7 and 60.5, respectively; yield and selectivity to HCN were 0.2 and 6.4, respectively; yield and selectivity to propylene were 0.0 and 0.0, respectively. This catalyst provides for little propane conversion when used alone. Example 41 In this example the gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst van a mixture of the catalyst of Example 1 and the catalyst of Example 2 in the weight ratio of the former to the latter of 0.064. Water was introduced through a septum a the top of the preheat leg, using a syringe pump. The reaction temperature was 500°C and the molar feed ratios were 8 propane/1.1 NH₃/2.1 O₂/1 H₂O. The contact time was 4.0 seconds. Analysis of the reactor effluent showed that propane conversion was 7.6 percent; yield and selectivity of propane to acrylonitrile were 4.0 and 52.8, respectively; yield and selectivity to HCN were 0.2 and 2.3, respectively; yield and selectivity to propylene were 0.7 and 9.6, respectively. Example 42 The gaseous feed components were metered through mass flow controllers into the bottom of tile reactor through the preheat leg. The catalyst was a mixture of the catalyst of Example 4 and the catalyst of Example 3 in the weight ratio of the former to the latter of 0.15. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 470°C and the molar feed ratios 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time was 2.0 seconds. Analysis of the reactor effluent showed that propane conversion was 13.7 percent; yield and selectivity of propane to acrylonitrile were 8.4 and 61.1, respectively; selectivity to propylene was 9.0, all over 2 hours. After 23 hours results were essentially identical to slightly improved. Comparative Example D The gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was the catalyst of Example 4 alone Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 470°C and the molar feed ratios were 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time was 0.3 seconds. Analysis of the reactor effluent showed that propane conversion was 18.3 percent; yield and selectivity of propane to acrylonitrile were 3.7 and 20.4, respectively; selectivity to propylene was 52.8. Example 43 The gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was a mixture of the catalyst of Example 5 and the catalyst of Example 3 in the weight ratio of the former to the latter of 0.20. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 470°C and the molar feed ratios were 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time was 2.2 seconds. Analysis of the reactor effluent showed that propane conversion was 12.4 percent; yield and selectivity of propane to acrylonitrile were 7.3 and 58.6, respectively; selectivity to propylene was 10.0. Comparative Example E The gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was the catalyst of Example 5 alone. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 470°C and the molar feed ratios were 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time was 0.3 seconds. Analysis of the reactor effluent showed that propane conversion was 14.3 percent; yield and selectivity of propane to acrylonitrile were 2.4 and 17.0, respectively; selectivity to propylene was 56.0%. Example 44 The gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was a mixture of the catalyst of Example 6 and the catalyst of Example 3 in the weight ratio of the former to the latter of 0.20. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 470°C and the molar feed ratios were 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time was 2.2 seconds. Analysis of the reactor effluent showed that propane conversion was 10.5 percent; yield and selectivity of propane to acrylonitrile were 6.0 and 57.3, respectively; selectivity to propylene was 11.0%. Comparative Example F The gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was the catalyst of Example 6 alone. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 470°C and the molar feed ratios were 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time was 0.2 seconds. Analysis of the reactor effluent showed that propane conversion was 11.9 percent; yield and selectivity of propane to acrylonitrile were 1.5 and 12.9, respectively; selectivity to propylene was 61.0%. Example 45 The gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was a mixture of the catalyst of Example 7 and the catalyst of Example 3 in the weight ratio of the former to the latter of 0.20. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 470°C and the molar feed ratios were 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time was 2.1 seconds. Analysis of the reactor effluent showed that propane conversion was 15.0 percent; yield and selectivity of propane to acrylonitrile were 8.7 and 58.0, respectively; selectivity to propylene was 13.4%. Comparative Example G The gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was the catalyst of Example 7 alone. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 470°C and the molar feed ratios were 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time was 0.4 seconds. Analysis of the reactor effluent showed that propane conversion was 13.1 percent; yield and selectivity of propane to acrylonitrile were 2.2 and 16.6, respectively; selectivity to propylene was 60.0%. Example 46 The gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was a mixture of the catalyst of Example 1 and the catalyst of Example 3 in the weight ratio of the former to the latter of 0.20. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 450°C and the molar feed ratios were 5 propane/1 NH₃/2 O₂/7.3 N₂/1 H₂O. The contact time was 3.7 seconds. Analysis of the reactor effluent showed that propane conversion was 14.5 percent; yield and selectivity of propane to acrylonitrile were 8.5 and 58.4, respectively; selectivity to propylene was 10.8%. Example 47 The gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was a mixture of the catalyst of Example 1 and the catalyst of Example 3 in the weight ratio of the former to the latter of 0.20. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 470°C and the molar feed ratios were 5 propane/1 NH₃/2 O₂/7.3 NH₂/1 H₂O. The contact time was 3.6 seconds. Analysis of the reactor effluent showed that propane conversion was 13.6 percent; yield and selectivity of propane to acrylonitrile were 8.4 and 61.8, respectively; selectivity to propylene was 8.8%. Example 48 The gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was a mixture of the catalyst of Example 1 and the catalyst of Example 3 in the weight ratio of the former to the latter of 0.20. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 450°C and the molar feed ratios were 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time was 1.9 seconds. Analysis of the reactor effluent showed that propane conversion was 12.4 percent; yield and selectivity of propane to acrylonitrile were 6.7 and 54.2, respectively; selectivity to propylene was 15.2%. Example 49 The gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was a mixture of the catalyst of Example 1 and the catalyst of Example 3 in the weight ratio of the former to the latter of 0.20. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 470°C and the molar feed ratios were 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time was 1.9 seconds. Analysis of the reactor effluent showed that propane conversion was 14.7 percent; yield and selectivity of propane to acrylonitrile were 8.9 and 60.5, respectively; selectivity to propylene was 9.0%. Example 50 The gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was a mixture of the catalyst of Example 1 and the catalyst of Example 3 in the weight ratio of the former to the latter of 0.09. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 450°C and the molar feed ratios were 3 propane/1 NH₃/2 O₂/7.3 N₂/1 H₂O. The contact time was 3.4 seconds. Analysis of the reactor effluent showed that propane conversion was 10.4 percent; yield and selectivity of propane to acrylonitrile were 6.3 and 61.0, respectively; selectivity to propylene was 9.3%. Example 51 The gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was a mixture of the catalyst of Example 1 and the catalyst of Example 3 in the weight ratio of the former to the latter of 0.09. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 470°C and the molar feed ratios were 3 propane/1 NH₃/2 O₂/7.3 N₂/1 H₂O. The contact time was 3.3 seconds. Analysis of the reactor effluent showed that propane conversion was 13.1 percent; yield and selectivity of propane to acrylonitrile were 8.2%, and 62.5%, respectively; selectivity to propylene was 5.5%. The productivity was 0.026 lbs of acrylonitrile per pound of catalyst mixture per hour. When Example 51 was repeated exactly, except that the molar ratios were 1 propane/1 NH₃/2 O₂/7.3 N₂/1 H₂O, the propane conversion was 17.7 percent; yield and selectivity of propane to acrylonitrile were 9.8% and 55.2%; selectivity to propylene was 7.4%. Productivity was 0.012 lbs acrylonitrile per lb. of catalyst per hour. Comparative Example H The gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was a mixture of the catalyst of Example 1 and the catalyst of Example 3 in the weight ratio of the former to the latter of about 0.75. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 500°C and the molar feed ratios were 1 propane/2 NH₃/3 O₂/6.9 N₂/1 H₂O. The contact time was 3.4 seconds. Analysis of the reactor effluent shoved that propane conversion was 78.3 percent; yield and selectivity of propane to acrylonitrile were 26.5 and 33.9, respectively; selectivity to propylene was 3.8%, data taken after 1 hour. Results after 24 hours were propane conversion 80.6 percent; yield and selectivity of propane to acrylonitrile 30.7 and 38.0, respectively; selectivity to propylene 4.2%. This example illustrates the importance of a stoichiometric excess as set forth herein of paraffin to both O₂ and NH₃ in the feed to the reaction zone, ultimate yields to acrylonitrile being too low for serious industrial consideration. Example 52 The gaseous feed components are metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst is a mixture of the catalyst of Example 5 and the catalyst of Example 8 in the weight ratio of the former to the latter of 0.15. Water is introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature is 470°C and the molar feed ratios are 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time is 2.2 seconds. Results similar to Example 42 are obtained, selectivity and yield to acrylonitrile being several times that of the yield and selectivity to propylene. Example 53 The gaseous feed components are metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst is a mixture of the catalyst of Example 1 and the catalyst of Example 9 in the weight ratio of the former to the latter of 0.15. Water is introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature is 470°C and the molar feed ratios are 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time is 2.2 seconds. Results similar to Example 42 are obtained, selectivity and yield to acrylonitrile being several times that of the yield and selectivity to propylene. Example 54 The gaseous feed components are metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst is a mixture of the catalyst of Example 4 and the catalyst of Example 10 in the weight ratio of the former to the latter of 0.15. Water is introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature is 470°C and the molar feed ratios are 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time is 2.2 seconds. Results similar to Example 42 are obtained, selectivity and yield to acrylonitrile being several times that of the yield and selectivity to propylene. Example 55 The gaseous feed components are metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst is a mixture of the catalyst of Example 4 and the catalyst of Example 11 in the weight ratio of the former to the latter of 0.15. Water is introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature is 470°C and the molar feed ratios are 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time is 2.2 seconds. Results similar to Example 42 are obtained, selectivity and yield to acrylonitrile being several times that of the yield and selectivity to propylene. Example 56 The gaseous feed components are metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst is a mixture of the catalyst of Example 7 and the catalyst of Example 12 in the weight ratio of the former to the latter of 0.15. Water is introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature is 470°C and the molar feed ratios are 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time is 2.2 seconds. Results similar to Example 42 are obtained, selectivity and yield to acrylonitrile being several times that of the yield and selectivity to propylene. Example 57 The gaseous feed components are metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst is a mixture of the catalyst of Example 7 and the catalyst of Example 13 in the weight ratio of the former to the latter of 0.15. Water is introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature is 470°C and the molar feed ratios are 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time is 2.2 seconds. Results similar to Example 42 are obtained, selectivity and yield to acrylonitrile being several times that of the yield and selectivity to propylene. Example 58 The gaseous feed components are metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst is a mixture of the catalyst of Example 6 and the catalyst of Example 14 in the weight ratio of the former to the latter of 0.15. Water is introduced through a septum at the top of the preheat leg, using a syringe pump The reaction temperature is 470°C and the molar feed ratios are 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time is 2.2 seconds. Results similar to Example 42 are obtained, selectivity and yield to acrylonitrile being several times that of the yield and selectivity to propylene. Example 59 The gaseous feed components are metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst is a mixture of the catalyst of Example 5 and the catalyst of Example 15 in the weight ratio of the former to the latter of 0.15. Water is introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature is 470°C and the molar feed ratios are 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time is 2.2 seconds. Results similar to Example 42 are obtained, selectivity and yield to acrylonitrile being several times that of the yield and selectivity to propylene. Example 60 The gaseous feed components are metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst is a mixture of the catalyst of Example 1 and the catalyst of Example 16 in the weight ratio of the former to the latter of 0.15. Water is introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature is 470°C and the molar feed ratios are 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time is 2.2 seconds. Results similar to Example 42 are obtained, selectivity and yield to acrylonitrile being several times that of the yield and selectivity to propylene. Example 61 The gaseous feed components are metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst is a mixture of the catalyst of Example 7 and the catalyst of Example 17 in the weight ratio of the former to the latter of 0.15. Water is introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature is 470°C and the molar feed ratios are 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time is 3.0 seconds. Results similar to Example 42 are obtained, selectivity and yield to acrylonitrile being several times that of the yield and selectivity to propylene. Example 62 The gaseous feed components are metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst is a mixture of the catalyst of Example 6 and the catalyst of Example 18 in the weight ratio of the former to the latter of 0.15. Water is introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature is 470°C and the molar feed ratios are 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time is 2.2 seconds. Results similar to Example 42 are obtained, selectivity and yield to acrylonitrile being several times that of the yield and selectivity to propylene. Example 63 The gaseous feed components are metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst is a mixture of the catalyst of Example 5 and the catalyst of Example 19 in the weight ratio of the former to the latter of 0.15. Water is introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature is 470°C and the molar feed ratios are 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time is 2.2 seconds. Results similar to Example 42 are obtained, selectivity and yield to acrylonitrile being several times that of the yield and selectivity to propylene. Example 64 The gaseous feed components are metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst is a mixture of the catalyst of Example 5 and the catalyst of Example 20 in the weight ratio of the former to the latter of 0.15. Water is introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature is 470°C and the molar feed ratios are 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time is 2.2 seconds. Results similar to Example 42 are obtained, selectivity and yield to acrylonitrile being several times that of the yield and selectivity to propylene. Example 65 The gaseous feed components are metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst is a mixture of the catalyst of Example 4 and the catalyst of Example 21 in the weight ratio of the former to the latter of 0.15. Water is introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature is 470°C and the molar feed ratios are 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time is 2.2 seconds. Results similar to Example 42 are obtained, selectivity and yield to acrylonitrile being several times that of the yield and selectivity to propylene. Example 66 The gaseous feed components are metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst is a mixture of the catalyst of Example 1 and the catalyst of Example 22 in the weight ratio of the former to the latter of 0.15. Water is introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature is 470°C and the molar feed ratios are 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time is 2.2 seconds. Results similar to Example 42 are obtained, selectivity and yield to acrylonitrile being several times that of the yield and selectivity to propylene. Example 67 The gaseous feed components are metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst is a mixture of the catalyst of Example 5 and the catalyst of Example 23 in the weight ratio of the former to the latter of 0.15. Water is introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature is 470°C and the molar feed ratios are 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time is 2.2 seconds. Results similar to Example 42 are obtained, selectivity and yield to acrylonitrile being several times that of the yield and selectivity to propylene. Example 68 The gaseous feed components are metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst is a mixture of the catalyst of Example 1 and the catalyst of Example 24 in the weight ratio of the former to the latter of 0.15. Water is introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature is 470°C and the molar feed ratios are 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time is 1.2 seconds. Results similar to Example 42 are obtained, selectivity and yield to acrylonitrile being several times that of the selectivity and yield to propylene. Example 69 The gaseous feed components are metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst is a mixture of the catalyst of Example 5 and the catalyst of Example 25 in the weight ratio of the former to the latter of 0.15. Water is introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature is 470°C and the molar feed ratios are 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time is 1.2 seconds. Results similar to Example 42 are obtained, selectivity and yield to acrylonitrile being several times that of the selectivity and yield to propylene. Example 70 The gaseous feed components are metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst is a mixture of the catalyst of Example 4 and the catalyst of Example 26 in the weight ratio of the former to the latter of 0.15. Water is introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature is 470°C and the molar feed ratios are 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time is 1.2 seconds. Results similar to Example 42 are obtained, selectivity and yield to acrylonitrile being several times that of the selectivity and yield to propylene. Example 71 The gaseous feed components are metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst is a mixture of the catalyst of Example 7 and the catalyst of Example 27 in the weight ratio of the former to the latter of 0.15. Water is introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature is 470°C and the molar feed ratios are 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time is 2.2 seconds. Results similar to Example 42 are obtained, selectivity and yield to acrylonitrile being several times that of the selectivity and yield to propylene. Example 72 The gaseous feed components are metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst is a mixture of the catalyst of Example 6 and the catalyst of Example 28 in the weight ratio of the former to the latter of 0.15. Water is introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature is 470°C and the molar feed ratios are 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time is 2.2 seconds. Results similar to Example 42 are obtained, selectivity and yield to acrylonitrile being several times that of the selectivity and yield to propylene. Example 73 The gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was a mixture of the catalyst of Example 29 and the catalyst of Example 3 in the weight ratio of the former to the latter of 0.036. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 470°C and the molar feed ratios were 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time was 1.8 seconds. Analysis of the reactor effluent showed that propane conversion was 10.4 percent; yield and selectivity of propane to acrylonitrile were 6.0 and 57.6%, respectively; selectivity to propylene was 9.0%. Comparative Example I The gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was the catalyst of Example 29 alone. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 470°C and the molar feed ratios were 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time was 0.3 seconds. Analysis of the reactor effluent showed that propane conversion was 20.7 percent; yield and selectivity of propane to acrylonitrile were 4.5% and 21.7%, respectively; selectivity to propylene was 48.0%. Example 74 The gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was a mixture of the catalyst of Example 30 and the catalyst of Example 32 in the weight ratio of the former to the latter of 0.035. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 470° and the molar feed ratios were 5 propane/ 1 NH₃/2 O₂/1 H₂O. The contact time was 2.1 seconds. Analysis of the reactor effluent showed that propane conversion was 11.2 percent; yield and selectivity of propane to acrylonitrile were 5.9% and 52.2%, respectively; selectivity to propylene was 9.8. Comparative Example J The gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was the catalyst of Example 30 alone. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 470°C and the molar feed ratios were 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time was 0.3 seconds. Analysis of the reactor effluent showed that propane conversion was 20.4 percent; yield and selectivity of propane to acrylonitrile were 4.1 and 20.1, respectively; selectivity to propylene was 48.6. Comparative Example K The gaseous feed components were metered through mass flow controllers into the bottom of the reactor through the preheat leg. The catalyst was a mixture of the catalyst of Example 31 and the catalyst of Example 32 in the weight ratio of the former to the latter of 0.035. Water was introduced through a septum at the top of the preheat leg, using a syringe pump. The reaction temperature was 470°C and the molar feed ratios were 5 propane/1 NH₃/2 O₂/1 H₂O. The contact time was 2.0 seconds. Analysis of the reactor effluent showed that propane conversion was 9.9 percent; yield and selectivity of propane to acrylonitrile were 4.7 and 47.8%, respectively; selectivity to propylene was 8.9. As will be evident to those skilled in the art various modifications of this invention can be made or followed in the light of the foregoing disclosure and discussion without departing from the spirit and scope of the disclosure or from the scope of the claims.

Claims: A process for the ammoxidation of a paraffin selected from propane and isobutane to acrylonitrile or methacrylonitrile which comprises contacting in a reaction zone said paraffin in the vapor phase in admixture with ammonia, molecular oxygen, and optionally an inert gaseous diluent, with an intimate particulate mixture of a first catalyst composition and a second catalyst composition, said feed to the reaction zone containing a mole ratio of paraffin: NH₃ in the range from 2 to 16 and a mole ratio of paraffin to O₂ in the range from 1 to 10, said first catalyst composition being 10-99 weight percent of a diluent/support and 90-1 weight percent of a catalyst having the components in the proportions indicated by the empirical formula: VSb m A a H b C c T t O x formula (1) where A is one or more of W, Sn Mo, B, P and Ge and includes at least 0.2 atoms of W; H is one or more of Fe, Co, Ni, Cr, Pb, Mn, Zn, Se, Te, Ga, In and As; C is one or more of an alkali metal and Tl; T is one or more of Ca, Sr and Ba; and where m is from 0.01 and up to 20; a is 0.2-10; b is 0-20; c is 0-20; t is 0-20; the ratio (a+b+c+t):(1+m) is 0.01-6; wherein x is determined by the oxidation state of other elements, and wherein the antimony has an average valency higher than +3 and the vanadium has an average valency lower than +5, said second catalyst composition being 0-99 weight percent of a diluent/support and 100-1 weight percent of a catalyst having the components in the proportions indicated by the empirical formula: Bi n Ce p D d E e F f Mo₁₂W g O y formula (2) where D is one or more of Fe, Mn, Pb, Co, Ni, Cu, Sn, P, Cr, Y, Mg, Ca, Sr, Ba and rare earths other than Ce and Sm; E is one or more of Sb, Ge, As, Se, Te and V; F is one or more of an alkali metal, Tl, Ag and Sm and where n is 0.01-24, p is 0.01-24, (n+p) is 0.1-24, d is 0-10, e is 0-10, f is 0-6, g is 0-8, and Y is determined by the oxidation state of the other elements, wherein the weight ratio in said mixture of said first catalyst composition to said second catalyst composition is in the range of 0.001 to 2.5. A process of claim 1 wherein said mole ratio of paraffin:NH₃ is in the range from 3 to 7. A process of claim 1 or 2 wherein said mole ratio of paraffin to O₂ is in the range from 1.5 to 5. A process according to claim 1 wherein the mole ratio of O₂ to NH₃ in the feed to the reaction zone is in the range from 1 to 10. A process according to claim 1 wherein the mole ratio of inert gaseous diluent to paraffin in the feed to the reaction zone is in the range from zero to 5. A process of claim 1 wherein A includes at least 0.2 atoms of W per atom of V and the total A atoms include at least 0.4 (W atoms + Sn atoms) per atom of V. A process of claim 1 wherein A includes at least 0.4 atoms of P per atom of V. A process of claim 1 wherein said support for the catalyst of formula (1) is selected from silica, alumina, titania, silica-niobia, silica-zirconia, silica-titania, silica-alumina, Nb₂O₅ and magnesia. A process of claim 1 wherein said support for the catalyst of formula (1) is selected from silica-alumina and alumina having 20-100 weight percent alumina; silica-titania and titania having 20-100 weight percent titania; silica-zirconia and zirconia having 80-100 weight percent zirconia; and silica-niobia and niobia having 30-100 weight percent niobia (Nb₂O₅). A process of any one of claim 1-9 wherein m is 2-10. A process of any one of claims 1-9 wherein m is 3-7. A process of any one of claims 1-7 wherein said diluent/support in said first catalyst composition comprises 20-100 weight percent alumina and 80 to zero weight percent silica. A process of claim 12 wherein said diluent/support in said first catalyst composition comprises 50-100 weight percent alumina and 50 to zero weight percent silica. A process of any one of the any one of claims 1-13 wherein said paraffin is propane. A catalytic mixture suitable for the ammoxidation of propane to acrylonitrile, which comprises an intimate particulate mixture of a first catalyst composition and a second catalyst composition, said first catalyst composition being 10-99 weight percent of a diluent/support and 90-1 weight percent of a catalyst having the components in the proportions indicated by the empirical formula: VSb m A a H b C c T t O x formula (1) where A is one or more of W, Sn, Mo, B, P and Ge and includes at least 0.2 atoms of W; H is one or more of Fe, Co, Ni, Cr, Pb, Mn, Zn, Se, Te, Ga, In and As; C is one or more of an alkali metal and Tl; T is one or more of Ca, Sr and Ba; and where m is from 0.01 and up to 20; a is 0.2-10; b is 0-20; c is 0-1; t is 0-20; the ratio (a+b+c+t) : (1+m) is 0.01-6; wherein x is determined by the oxidation state of other elements, and wherein the antimony has an average valency higher than +3 and the vanadium has an average valency lower than +5, wherein said diluent/support contains 20-100 weight percent alumina and is selected from silica-alumina anti alumina, said second catalyst composition being 0-99 weight percent of a diluent/support and 100-1 weight percent of a catalyst having the components in the proportions indicated by the empirical formula: Bi n Ce p D d E e F f Mo₁₂W g O y formula (2) where D is one or more of Fe, Mn, Pb, Co, Ni, Cu, Sn, P, Cr, Y, Mg, Ca, Sr, Ba and rare earths other than Ce and Sm; E is one or more of Sb, Ge, As, Se, Te and V; F is one or more of an alkali metal, Tl, Ag and Sm and where n is 0.01-24, p is 0.01-24, (n+p) is 0.1-24, d is 0-10, e is 0-10, f is 0-6, g is 0-8, y is determined by the oxidation state of other elements, wherein the weight ratio in said mixture of said first catalyst composition to said second catalyst composition is in the range of 0.001 to 2.5. A mixture of claim 15 wherein the total A atoms include at least 0.4 (W atoms + Sn atoms) per atom of V. A mixture of claim 15 wherein A includes at least 0.4 atoms of W per atom of V. A mixture of any one of claims 15-17 wherein m is 2-10. A mixture of any one of claims 15-17 wherein m is 3-7. A mixture of any one of claims; 15-17 wherein said diluent/support in said first catalyst composition comprises 50-100 weight percent alumina and 50 to zero weight percent silica. A mixture of claim 21 wherein said diluent/support in said first catalyst composition comprises 60-100 weight percent alumina and 40 to zero weight percent silica.

Inventors: BRAZDIL JAMES FRANK, GLAESER LINDA CLAIRE, TOFT MARK ANTHONY, BRAZDIL, JAMES FRANK, GLAESER, LINDA CLAIRE, TOFT, MARK ANTHONY
Applicants: STANDARD OIL CO OHIO, THE STANDARD OIL COMPANY
Application year: 1988
Main classification: C07C253
IPC codes: B01J27, C07C253, C07C255, B01J23, C07C67, B01J37