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Patent US4876228 - Zeolite modifications - Google Patents
A method is disclosed for modifying an aluminosilicate-containing inorganic solid having a predetermined ion exchange capacity and containing an extractable silica by contacting, in the absence of added organic nitrogen or organic phosphorous compound and added activating metal oxide, the porous solid...http://www.google.com/patents/US4876228?utm_source=gb-gplus-sharePatent US4876228 - Zeolite modifications
Publication number US4876228 A
Application number US 07/163,191
Publication number 07163191, 163191, US 4876228 A, US 4876228A, US-A-4876228, US4876228 A, US4876228A
Inventors Clarence D. Chang, Cynthia T-W Chu, Pochen Chu, Ralph M. Dessau, William E. Garwood, Guenter H. Kuehl, Joseph N. Miale, David S. Shihabi
Patent Citations (11), Non-Patent Citations (1), Referenced by (10), Classifications (15), Legal Events (5)
Zeolite modifications
US 4876228 A
A method is disclosed for modifying an aluminosilicate-containing inorganic solid having a predetermined ion exchange capacity and containing an extractable silica by contacting, in the absence of added organic nitrogen or organic phosphorous compound and added activating metal oxide, the porous solid with liquid water at a pH of at least 6, at a temperature of up to 370° C. for about 1 to 100 hours, and recovering a crystalline solid having an ion exchange capacity greater than the starting inorganic solid.
1. A method for modifying a calcined unbound porous crystalline high silica content inorganic solid comprising a calcined aluminosilicate having a silica to alumina ratio of at least about 70 and having a predetermined ion-exchange capacity after calcining, said solid being further characterized by the presence of extractable silica, which method comprises:
contacting in the absence of added organic nitrogen, organic phosphorus compound, or activating metal oxide, said porous solid with liquid water containing alkali metal cation, and anions selected from the group consisting of carbonate and nitrate, at a pH from about 7 to 12 and for from less than about one hour to 100 hours at a temperature up to 370° C.;
and recovering a crystalline solid having an ion-exchange capacity greater than said porous crystalline high silica-content inorganic solid.
2. The method of claim 1 wherein said time and temperature are selected so as to yield at least 10 parts by weight of said recovered solid per 100 parts of said porous crystalline high silica-content inorganic solid.
3. The method of claim 1 wherein said liquid water contains carbonate.
4. The method of claim 1 wherein said liquid water contains nitrate.
5. The method of claim 1 wherein said liquid water contains carbonate and nitrate.
6. The method of claim 3 wherein said liquid water containing alkali metal cation is 0.5M Na2 CO3 solution.
7. The method of claim 1 wherein said liquid water containing alkali metal cation is an 0.5M/0.6M Na2 CO3 /NaNO3 solution.
8. The method of claim 1 wherein said recovered crystalline solid is ammonium-exchanged and then calcined.
9. The method of claim 1 wherein said silica to alumina molar ratio is about 70 to about 850.
This invention is a continuation of Ser. No. 024,904 filed Mar. 12, 1987 (abandoned), which is a continuation of Ser. No. 724,370 filed Apr. 17, 1985 (abandoned), which is a continuation-in-part of Ser. No. 631,687 filed July 16, 1984 now U.S. Pat. No. 4,559,315, which is a continuation in part Ser. No. 465,987 filed Feb. 14, 1983 now U.S. Pat. No. 4,513,091. Ser. No. 724,370 is also a continuation-in-part of Ser. No. 555,118 filed Nov. 25, 1983 now U.S. Pat. No. 4,550,092 which is a division of Ser. No. 317,037 filed Nov. 21, 1981 now U.S. Pat. No. 4,435,516.
This invention is broadly concerned with modifying a pre-formed highly siliceous crystalline zeolite to increase its ion exchange capacity and its acid catalytic activity, and with the use of such modified zeolites in organic conversion reactions and for ion-exchange separations.
Zeolite catalysts have become widely used in the processing of petroleum and in the production of various petro- chemicals. Acid catalyzed reactions such as cracking, hydro- cracking, catalytic dewaxing, alkylation, dealkylation, transalkylation, isomerization, polymerization, addition, disproportionation, conversion of methanol to hydrocarbons, and other acid catalyzed reactions may be performed with the aid of these catalysts. Both natural and synthetic zeolites are known to be active for these reactions.
The common crystalline zeolite catalysts are the aluminosilicates such as Zeolites A, X, Y and mordenite. Structurally, each such material can be described as a robust three dimensional framework of Si04 and Al04 tetrahedra that are crosslinked by the sharing of oxygen atoms whereby the ratio of total aluminum and silicon atoms to oxygen is 1:2. These structures (as well as other crystalline zeolites of catalytic usefulness) are porous, and permit access of reactant molecules to the interior of the crystal through windows formed of eight-membered rings (small pore) or of twelve-membered rings (large pore). The electrovalence of the aluminum that is tetrahedrally contained in the robust framework is balanced by the inclusion of cations in the channels (pores) of the crystal.
M.sub.2 /nO.Al.sub.2 O.sub.3.xSiO.sub.2.yH.sub.2 O
With few exceptions, (such as with Zeolite A wherein x =2) thre are fewer alumina tetrahedra than silica tetrahedra in the robust frameworks of the crystalline zeolites. Thus, in general, aluminum represents the minor tetrahedrally coordinated constituent of the robust frameworks of the common zeolites found in nature or prepared by the usual synthetic methods that employ only inorganic reagents.
It is generally recognized that the composition of the robust framework of the synthetic common zeolites, wherein x =2 t0 10, may be varied within relatively narrow limits by changing the proportion of reactants, e.g., by changing the concentration of the silica relative to the alumina in the zeolite forming mixture. However, definite limits, for example in the maximum obtainable silica to alumina ratio, are observed. Synthetic faujasites having a silica to alumina ratio of about 5.2 to 5.6 can be obtained by changing said relative proportions. However, if the silica proportion is increased above the level which produces the 5.6 ratio, no commensurate increase in the silica to alumina ratio of the crystallized synthetic faujasite is observed. Thus, the silica to alumina ratio of about 5.6 must be considered an upper limit for synthetic faujasite in a preparative process using conventional reagents. Corresponding limits in the silica to alumina ratio of mordenite and erionite via the synthetic pathway are also observed.
Unlike the common zeolites decribed above wherein x =2 to 5, the silica to alumina ratio for at least some of the high silica content zeolites is unbounded, i.e. the ratio may be infinitely large. ZSM-5 is one such example. U.S. Pat. No. Re. 29,948 to Dwyer et al. discloses a crystalline organosilicate essentially free of aluminum and exhibiting an X-ray diffraction pattern characteristic of ZSM-5 type aluminosilicates. Some other high silica content zeolites, however, appear to behave more like the common zeolites in that the upper limit of the compositional range of the crystals is fixed regardless of the silica content of the forming solution.
It is sometimes desirable to obtain a particular zeolite, for any of several reasons, with higher or a lower silica to alumina ratio than is available by direct synthesis. With ion-exchange applications, for example and for catalytic reactions such as hydrocracking which require high acidity catalysts, low silica to alumina ratios are favorable. For structural stability to heat and steam, or high-temperature xylene isomerization, high silica to alumina ratios are required.
This invention provides a method whereby a preformed high silica content crystalline inorganic solid may be readily modified, in the absence of added organic nitrogen compounds and/or added organic phosphorous compounds, to increase the ion exchange capacity and the catalytic activity of the preformed zeolite. The method comprises contacting the preformed crystals with liquid water at a pH of at least about 6 for from less than about one hour to about 100 hours at a temperature up to 370° C., and recovering a crystalline solid having an ion-exchange capacity greater than the preformed material. The method provided may be conducted either with the porous solid crystals or with a physical mixture of the porous solid crystals and an activating metal oxide, all as more fully described hereinbelow.
The preformed, porous crystalline high silica content inorganic solid to be modified by the method of this invention are often referred to as zeolites, although there is controversy among various workers about the propriety of using the term "zeolites" to describe such solids. In this specification we shall sometimes use the terms interchangeably, it being understood that either term refers to a structure in which the major framework component is silica and a minor framework element in present even if in only very small amounts.
A preferred class of porous crystalline solids is that in which the silica to alumina (or other minor element) ratio is at least 12, and which have a substantial sorption capacity for normal hexane.
The preferred type zeolites referred to herein have an effective pore size such as to freely sorb normal hexane. In addition, the structure must provide constrained access to larger molecules. It is sometimes possible to judge from a known crystal structure whether such constrained access exists. For example, if the only pore windows in a crystal are formed by 8-membered rings of oxygen atoms, then access to molecules of larger cross-section than normal hexane is excluded and the zeolite is not of the ZSM-5 type. Windows of 10-membered rings are preferred, although in some instances excessive puckering of the rings or pore blockage may render these zeolites ineffective. 12-membered rings usually do not offer sufficient constraint to produce the advantageous conversions, although the puckered 12-ring structure of TMA offretite shows constrained access. Other 12-ring structures may exist which, due to pore blockage or to other cause, may be operative.
The Constraint Index approximates the ratio of the cracking rate constants for the two hydrocarbons. Preferred zeolites suitable for the present invention are those having a Constraint Index of 1 to 12. C.I. values for some typical zeolites are:
TABLE VI______________________________________CAS                 C.I.______________________________________ZSM-4               0.5ZSM-5               8.3ZSM-11              8.7ZSM-12              2ZSM-23              9.1ZSM-35              4.5ZSM-38              2TMA Offretite       3.7Beta                0.6H--Zeolon (mordenite)               0.4REY                 0.4Amorphous Silica-Alumina               0.6Erionite            38______________________________________
The above-described Constraint Index is an important definition of those zeolites which are preferred and useful in the instant invention. The very nature of this parameter and the recited technique by which it is determined, however, admit of the possibility that a given zeolite can be tested under somewhat different conditions and thereby have different Constraint Indexes. Constraint Index seems to vary somewhat with severity of operation (conversion) and the presence or absence of binders. Therefore, it will be appreciated that it may be possible to so select test conditions to establish more than one value in the range of 1 to 12 for the Constraint Index of a particular zeolite. Such a zeolite exhibits the constrained access as herein defined and is to be regarded as having a Constraint Index of 1 to 12. Also contemplated herein as having a Constraint Index of 1 to 12 and therefore within the scope of the novel class of highly siliceous zeolites are those zeolites which, when tested under two or more sets of conditions within the above-specified ranges of temperature and conversion, produce a value of the Constraint Index slightly less than 1, e.g. 0.9, or somewhat greater than 12, e.g. 14 or 15, with at least one other value of 1 to 12. Thus, it should be understood that the Constraint Index value as used herein is an inclusive rather than an exclusive value. That is, a zeolite when tested by any combination of conditions within the testing definition set forth hereinabove and found to have a Constraint Index of 1 to 12 is intended to be included in the instant catalyst definition regardless that the same identical zeolite tested under other defined conditions may give a Constraint Index value outside of 1 to 12.
For ZSM-5 type zeolites of very high silica to alumina ratio, such as 1600:1, the Constraint Index cannot be measured reliably because of the low activity of the zeolite. In such cases reliance on X-ray pattern is useful. Many such zeolites, after activation by the method of this invention, become active enough to make Constrain Index evaluation feasible.
The class of zeolites defined herein is exemplified by ZSM-5, ZSM-11, ZSM-12, ZSM-21 ZSM-23, ZSM-35, ZSM-38, ZSM 48, and other similar materials. U.S. Pat. No. 3,702,886 describing and claiming ZSM-5 is incorporated herein by reference.
The ZSM-5 type zeolites referred to herein have a crystal framework density, in the dry hydrogen form, of not less than about 1.6 grams per cubic centimeter. The dry density for known crystal structures may be calculated from the number of silicon plus aluminum atoms per 1000 cubic Angstroms, as given, e.g., on Page 19 of the article on Zeolite Structure by W. M. Meier. This paper, the entire contents of which are incorporated herein by reference, is included in "Proceedings of the Conference on Molecular Sieves, London, April 1967," published by the Society of Chemical Industry, London, 1968. When the crystal structure is unkown, the crystal framework density may be determined by classical pycnometer techniques. For example, it may be determined by immersing the dry hydrogen form of the zeolite in an organic solvent not sorbed by the crystal. Or, the crystal density may be determined by mercury porosimetry, since mercury will fill the interstices between crystal but will not penetrate the intracrystalline free space.
Crystal framework densities of some typical zeolites which may be modified by the method of this invention, including some which are not within the purview of this invention, are:
TABLE VII______________________________________          Void         FrameworkZeolite        Volume       Density______________________________________Ferrierite     0.28 cc/cc   1.76 g/ccMordenite      .28          1.7ZSM-5, 11      .29          1.79ZSM-12         --           1.8ZSM-23         --           2.0Dachiardite    .32          1.72L              .32          1.61Clinoptilolite .34          1.71Laumontite     .34          1.77ZSM-4, Omega   .38          1.65Heulandite     .39          1.69P              .41          1.57Offretite      .40          1.55Levynite       .40          1.54Erionite       .35          1.51Gmelinite      .44          1.46Chabazite      .47          1.45A              .5           1.3Y              .48          1.27______________________________________
The preferred crystals that are treated by the method of this invention may be incorporated in another material usually referred to as a matrix or binder. Such matrix materials include synthetic or naturally occurring substances as well as inorganic materials such as clay, silica and/or metal oxides. The latter may be either naturally occurring or in the form of gelatinous precipitates or gels including mixtures of silica and metal oxides. Naturally occurring clays which can be composited with the zeolite include those of the montmorillonite and kaolin families, which families include the sub-bentonites and the kaolins commonly known as Dixie, McNamee, Georgia and Florida clays or others in which the main mineral constituent is halloysite, kaolinite, dickite, nacrite or anauxite. Such clays can be used in the raw state as originally mined or initially subjected to calcination, acid treatment or chemical modification.
The term "acid catalytic activity" as used herein refers to the effectiveness of the zeolite, when in suitable form, for catalyzing reactions known to be promoted by so-called acid catalysts. Catalytic cracking, hydrocracking, skelatal isomerization catalytic dewaxing, and various aromatic hydrocarbon reactions such as alkylation, dealkylation, isomerization and disproportionation, are hydrocarbon conversion reactions which fall in the category of acid catalyzed reactions. Other reactions, such as alcohol dehydration, are also in this class.
As is known in the art, the acid catalytic activity of a zeolite may be measured by its "alpha value", which is the ratio of the rate constant of a test sample for cracking normal hexane to the rate constant of a standard reference catalyst. Thus, an alpha value =1 means that the test sample and the reference standard have about the same activity. The alpha test is described in U.S. Pat. No. 3,354,078 and in The Journal of Catalysis, Vol. IV, pp. 522-529 (August 1965), both of which are incorporated herein by reference. Measurement of the "alpha value" is useful to assess the extent of catalyst activity before treatment, and also the degree of activation achieved with any sample treated by the method of this invention. For this purpose, the zeolite is converted to the hydrogen form before evaluation. However, other conversions also may be used to assess catalytic activity, and the zeolite need not always be in the hydrogen form, as illustrated above by Examples 24-25 wherein methanol conversion is used.
The method of this invention is believed to effect insertion of aluminum into the robust framework of the zeolite, without substantial change of the crystal structure, i.e. a ZSM-5 type zeolite product is produced. The increased ion-exchange capacity of the product may be measured by ordinary ion-exchange techniques, or by temperature programmed desorption of ammonia. The ammonia desorption/TGA technique is described in a publication by G. T. Kerr in Thermochemica Acta, the contents of which are incorporated herein by reference.
The products produced by this invention may be converted to the hydrogen or to any other form suitable for a particular application by methods known to those skilled in the art.
The preformed, high silica-content crystalline inorganic solid that may be modified by the method of this invention may be any crystalline solid of the type described including the preferred zeolites, and which have a silica to alumina mol ratio greater than about 10 and further characterized by a measureable content of silica extractable by a solution of sodium hydroxide.
The most simple test for the presence of extractable silica is to place a 1 gram sample of the calcined zeolite crystals, in the absence of added activating oxide and in the ammonium form, in 50 ml of 1N solution of sodium hydroxide and allow it to stand at room temperature for about 72 hours. If the crystal dissolves either partially or completely, this is a clear test showing the presence of extractable silica. Another method which is useful is to suspend the crystals as the hydrogen form in demineralized water and to conductimerically titrate at moderately elevated temperature with 0.1N sodium hydroxide. Apparent consumption of sodium hydroxide in excess of the measured ion-exchange capacity (e.g., 1.5 to 2×) is evidence for the formation of sodium silicate in solution. The latter may be determined independently for confirmation.
While not wishing to be bound by theory, the experimental results are consistent with the concept that exctractable silica plays a role in the method of this invention by creating crystal defects for accommodating an available added minor element in the rigid framework, or in the alternative (when no added minor element is available) by permitting selective removal of silica with possible reorganization of the remaining framework elements.
There are several embodiments of the present invention, as illustrated by the examples given below. All of these result in a higher catalytic activity for acid catalyzed reactions, as indicated by the alpha test or by a specific conversion, and the ion exchange capacity measured as meq/gram of product is higher than the meq/gram of preformed crystals.
In general, modification by the method of this invention proceeds more rapidly if the preformed crystals are first freed of organic matter that may be present by calcination, or at least pyrolyzed in nitrogen, but even in the absence of such treatment the method is still effective. The modification proceeds more rapidly the higher the silica alumina content of the preformed crystals. And it proceeds much more rapidly at higher concentrations of hydroxyl ion, especially in the presence of an alkali metal cation. The presence of an activating metal oxide also facilitates the conversion to the modified product.
A sample of this catalyst was contacted with 100% steam at one atmosphere and 800° F. for 18 hours. The steam treated product was found to have an alpha value of 17.6. After alpha measurement the catalyst was air regenerated at 1000° F. Regeneration at 1000° F. gave an alpha value of 17.4 A Constrained Index (C.I.) of 1.6 at 850° F. was obtained for the steamed extrudate. The C.I. value obtained is consistent with conventional ZSM-5 type catalysts, indicating that the enhanced activity is due to additional stable sites formed within the internal pores of the zeolites.
TABLE I______________________________________Steaming Time (hrs.)            Alpha Activity______________________________________0                6.16                7.218               7.645               7.294               7.0______________________________________
Two parts of the binder-free 1600:1 zeolite ZSM-5 of Example 2 in the hydrogen form produced by the air calcination of the ammonia form zeolite were mixed well with one part of alpha-alumina momohydrate and the mixture was then pelletized and steamed for 18 hours in 100% steam at atmospheric pressure and 425° C. The alpha value of the steamed catalyst was 6.7, showing that mere admixture of the zeolite and the binder is insufficient for activation.
The 1600:1 zeolite ZSM-5 of the preceding Examples in the ammonium form was mulled with 35% alpha alumina monohydrate by ball milling after which the mixture was extruded into 1.6 mm cylindrical pellets The extruded catalyst was then dried in air at 120° C., precalcined in nitrogen at 540° C., followed by an ammonium exchange, air drying at 120° C., air calcination and steaming for 18 hours at 425° C. under atmospheric pressure. The alpha value of the steamed catalyst was 12.3, a substantial increase over the original alpha value of 6.1.
A retained portion of a similarly prepared batch of 70:1 crystals was calcined, ammonium exchanged and the Bronsted acid site content was found to be 0.47 MEQ H/gm, i.e., 0.47 milliequivalents of hydrogen per gram of zeolite. The Bronsted acidity of the extrudate also was found 0.47 MEQ H/gm zeolite. The 70:1 ammonium extrudate is identified below as Extrudate 1.
The Bronsted acidity of retained portions of the 1600:1 binder-free ammonium form of ZSM-5 from Example 5, and of the 1600:1 ammonium form extrudate (Extrudate 2) from the same example were also determined. The binder free was found to have 0.02 MEQ H/gm zeolite, and Extrudate 2, 0.057 MEQ H/gm zeolite.
All of the above determinations of acidity were made by TGA filtration.
TABLE II______________________________________       Alpha     Bronsted Activity       Value     (MEQ H/gm zeolite)______________________________________Untreated Extrudate 1         254         0.47Hydrothermally-treatedExtrudate 1   151         0.33Untreated Extrudate 2         7.7 (estimated)                     .057Hydrothermally-treatedExtrudate 2   15          0.13______________________________________
EXAMPLE S 1B to 4B
______________________________________ExampleNo.     Temp. (°C.)              Time    Acid Activity (α)                                 Notes______________________________________1       165        1 day   41         --2       100        8 days  4.5        --3       170        1 day   33         H.sub.2 O loss4       173        14 hrs. 23         --______________________________________
EXAMPLE S 5B-7B
______________________________________Example No.     Alumina   Treatment   Activity (α)______________________________________5         nil       none        0.0156         binder    hydrothermal                           417         beads     hydrothermal*                           7______________________________________ *Loss of H.sub.2 O indicated. Beads separated from treated zeolite prior to activity test.
EXAMPLE S 8B to 11B
The procedure of Example 7 is repeated using an admixture of HZSM-5 and α-Al2 O3 beads, except that the standard heating period is 1 day.
______________________________________Example No.      Temp. (°C.)                   Activity Note______________________________________8          165          7        --9          100          0.3      --10         170          2        H.sub.2 O Loss11         165          0.5      Steam Only______________________________________
Examples 8, 9 and 10 show how hydrothermal treatment in contact with an aqueous liquid can improve activity markedly (14×), as compared to steaming, where the role of water as a transport medium is necessarily restricted. By fully covering the catalyst with water during hydrothermal treatment enhancement is maximized.
__________________________________________________________________________Example No.  Temp °C.       Pressure            Treatment                    Time Cat. Activity__________________________________________________________________________2      100  1 atmo.            Hydrothermal                    8 days                         4.54      173  125 psi            Hydrothermal                    14 hours                         2312     228  1 atmo.            steam   20 hours                         1.6control  --   --   none    --   1.4__________________________________________________________________________
A high silica ZSM-5 composite catalyst is made by mixing 65 parts by weight of ZSM-5 zeolite (SiO2 :Al2 O3 =2327:1) with 35 parts by weight (dry calcined basis) of alpha aluminum monohydrate (Kaiser) and mulled with sufficient water to form an extrudable mass. After forming 1/16" extrudate composite, the catalyst is dried and precalcined at 1000° F. (540° C.) in nitrogen atmosphere for three hours. The calcined composite is ion exchanged with 1 N ammonium nitrate, dried and calcined again to obtain the hydrogen form. The exchanged catalyst contains 0.09% Na and has an alpha value of 2.
The hydrothermal treatment is conducted at 148 C (300° F.) for 24 hours in an autoclave, using about 5 volumes of water per volume of composite catalyst. The recovered catalyst is dried at (110° C.) (230° F.) and calcined at 540° C. (1000° F.) for three hours. The treated catalyst has an alpha activity of 38.
Significant increases in the alpha value may be obtained with zeolites having a silica to alumina ratio of 1600:1 or more. Commensurate results may be obtained with other zeolites of differing silica to alumina ratio. The enhancement in activity is believed to be caused by the creation of additional, stable active internal sites in the zeolite because after the hydrothermal treatment is complete, the Constraint Index remains consistent with that of the original zeolite structure although the alpha value has increased significantly. The catalyst thereof retains its original selectivity but with an improved acid activity.
The activated zeolite compositions produced by the present invention may be used as catalysts in acid catalyzed conversion reactions of the kind catalyzed by the type of zeolite used in the method. Hydrocarbon conversion reactions such as cracking, hydrocracking, alkylation, dealkylation, transalkylation, isomerization, polymerization, disproportionation and aromatization are particularly important but other reactions such as the conversion of oxygenates such as methanol or dimethyl ether to hydrocarbons are also of interest. The conditions employed in these reactions will be those appropriate to the particular catalyst being used, having due regard to its enhanced activity.
EXAMPLE 1C Preparation of ZSM-5 containing about 50 ppm alumina (about 38,000:1 silica-to-alumina ratio)
ZSM-5 crystals were synthesized from a formulation containing tetraethylorthosilicate, sodium hydroxide, tetrapropylammonium bromide, and water at 212° F. with intensive agitation. Special precautions were taken to prevent alumina contamination from the crystallization equipment and the environment.
A 50 g quantity of the material was calcined in an ammonia atmosphere at 1000° F. for three hours to decompose the organic components in the zeolite. The product was pure white without any signs of a carbon residue. The NH3 calcined material was subsequently purged with nitrogen and then air for one hour to remove any absorbed NH3. The sodium content of the sample was reduced to 0.01 wt. % by treatment with a 0.1 N ammonium nitrate solution followed by hot water washing. The sample was then dried and its chemical composition was determined to be as follows:
______________________________________  Al.sub.2 O.sub.3, ppm          50  SiO.sub.2, wt. %          99  Na, wt. %          0.01  N, wt. %          0.05  C, wt. %          0.03  Ash, wt. %          99.6______________________________________
A portion of a zeolite produced in accordance with Example 1 was calcined in a muffle furnace at 1000° F. for three hours, sized to 30-60 mesh, and 2.5 g (4.8 cc) were charged to a 5/16" ID stainless steel microreactor. The ZSM-5 was treated in situ with hydrogen at 900° F. for one hour. Propylene, admixed with 50 volume percent of hydrogen, was then passed over the catalyst at 500 psig (total pressure-1000 psig), 0.4 WHSV, 400° F. for two hours. No C6 +liquid product was obtained.
EXAMPLE 3C Conversion of Propylene over a physical mixture of 50 ppm Al2 O3 ZSM-5 and alumina
A mixture of 1.63 g (2.9 cc) 50 ppm Al2 O3 ZSM-5 plus 0.87 g (1.8 cc) alpha alumina monohydrate, both sized to 30-60 mesh and calcined at 1000° F. for three hours, was charged to the reactor and treated again in situ with hydrogen at 1000° F. for one hour. Propylene was then passed over the catalyst under the same conditions as in Example 2 for successive periods of 161/2 and 221/2 hours. Again, no C6 + liquid was formed.
EXAMPLE 4C Preparation of 50 ppm Al2 O3 ZSM-5 with 35 wt. % alumina binder
The 50 ppm Al2 O3 ZSM-5, as synthesized, was mulled with 35 wt. % alpha alumina monohydrate with added deionized water, extruded (1/16") at 25 t/in2 pressure, dired at 230° F., precalcined in ammonia for three hours at 1000° F., ammonium exchanged to insure sodium content less than 0.02 wt. %, dried at 230° F., and calcined in air for three hours at 1000° F.
EXAMPLE 5C Propylene Over 50 ppm Al2 O3 with 35 wt. % alumina binder
A 2.50 g quantity of the product from Example 4, sized to 30-60 mesh, was charged to the reactor, treated with hydrogen in situ for one hour at 900° F. Then propylene was passed over the catalyst under the conditions of Examples 2 and 3. Results are shown below:
______________________________________Yields______________________________________Material Balance Time,Hrs.               191/2   22Time on Stream, Days              0.8     0.9Yields, wt. %C.sub.1 + C.sub.2  0.1     0.1C.sub.3 =          22.7    22.7C.sub.3            2.4     3.0C.sub.4 's         1.2     1.4C.sub.5 's         1.8     1.4C.sub.6 +          71.9    71.4              100.0   100.0______________________________________
The C6 + liquid from the two runs was composited and distilled to give 28.6 wt. % 330° F.- gasoline and 42.9 wt. % 330° F.+ fuel oil. The gasoline had an octane number (R+O) of 94 and the fuel oil a pour point of -70° F., diesel index 67.
______________________________________         330° F..sup.-  Gasoline______________________________________Yield, wt. %    28.6Gravity, °API           64.7Gravity, specific           0.7213O.N., R + O     94Boiling Range, °F.5%              13250%             26795%             328______________________________________
______________________________________       330° F..sup.+   Distillate (Fuel Oil)______________________________________Yield, wt. %  42.9Gravity, °API         42.7Gravity, specific         0.8123Pour Point, °F.         -75Aniline No.   157.2Diesel Index  67Hydrogen, wt. %         13.93Carbon        86.15H/C Ratio     1.92Boiling Range, °F.5%            33950%           45895%           651______________________________________
EXAMPLE 6C Waxy Lube Raffinate Charge
__________________________________________________________________________Lube Dewaxing               Mixture*               Example 1    ConventionalCatalyst            + Al.sub.2 O.sub.3                      Example 4                            Catalyst__________________________________________________________________________Temperature, °F.               650    651   551Material Balance Time, Hrs.         CHARGE               181/2  18    18Yields, wt. %C.sub.1 + C.sub.2   LIQUID 0.1   0.1C.sub.3             PRODUCT                      0.9   2.2C.sub.4                    2.5   3.8C.sub.5                    1.8   2.1C.sub.6 -650° F.    9.4   8.8650° F.+Lube        85.1  82.8650° F. Lube PropertiesGravity, °API         29.1         28.4  28.5Gravity, specific         0.8811       0.8849                            0.8844Pour Point, °F.         115   115    +20   +10KV @ 40° C., cs         --    --     95.08 109.0KV @ 100° C., cs         9.91  --     10.77 11.42V.I.          --    --     96.3  90.0__________________________________________________________________________ *Physical mixture of 1.7 g (3.0 cc) Example 1 plus 0.9 g (1.8 cc) alumina
EXAMPLE S 7C-8C
The following examples will illustrate that the use of zeolites having a significant amount of alumina, i.e. a silica/alumina mole ratio of are not readily activated by mixing with binder, but rather, their activity is diluted.
Example 7C 70/l SiO2 /Al2 O3 ZSM-5 2.5 wt Al2 O3, 25,000 ppm
Propylene was passed over the 70/l SiO2 /Al2 O3 ZSM-5 catalyst, with and without 35% alumina binder under the same conditions as those used in Examples 2, 3 and 5. Results are listed below:
______________________________________Catalyst      No Binder 35% Alumina Binder______________________________________Temperature, °F.         401       400WHSV          0.6       0.4Material BalanceTime, Hrs.    17        22.5Yields, Wt. %C.sub.1 + C.sub.2         0.1       0.1C.sub.3 =     1.2       2.0C.sub.3       1.9       3.1C.sub.4 's    0.9       0.4C.sub.5 's    1.3       0.6C.sub.6 +     94.6      93.9         100.0     100.0Liquid ProductBoiling Range, °F.5%            246       22110%           314       26630%           453       36850%           539       44670%           604       52590%           733       64195%           786       709______________________________________
In this example a ZSM-5 having a silica-to-alumina ratio of 1600:1 (about 0.10 wt. % alumina, or 1,000 ppm) was used. The waxy lube raffinate of Example 6 was processed over this 1600/l SiO2 /Al2 O3 ZSM-5, with and without 35% alumina binder. Conditions were again the same as those used in that example.
______________________________________Catalyst        No Binder*                     35% Alumina Binder______________________________________Temperature, °F.           651       650Material Balance TimeHrs.            19        18Yields, wt. %C.sub.1 + C.sub.2           0.1       0.1C.sub.3         1.6       2.1C.sub.4         2.9       5.0C.sub.5         1.8       2.7C.sub.6 -650° F.           10.7      13.7650° F.+ Lube           82.5      76.2650° F.+ Lube PropertiesGravity, °API           27.4      27.1Specific        0.8905    0.8922Pour Point, °F.           -20       +10KV @ 40° C., cs           113.9     109.1KV @ 100° C., cs           11.44     11.21V.I.            84.6      86.2______________________________________ *Physical mixture of ZSM5 plus alumina, alumina equal in weight to that present in bound catalyst
The procedure of Example 4 was repeated with the sole exception that no water was used in mulling the aluminum with a high silica ZSM-5.
In this example alumina alone was mulled with added water (no high silica zeolite) and then the high silica zeolite of Example 2 was wetted with the extract liquid and thereafter processed in identical manner to Example 2, i.e. ammonium precalcination for three hours at 1000°, base exchanged with an ammonium solution to reduce the sodium content to 0.02 wt. % followed by air calcination.
TABLE__________________________________________________________________________Conversion of Propylene            Physical      Wetted With       Pure Mixture                   Dry-Mulled                          H.sub.2 O Extract                                 Wet-Mulled                                         Alumina       Crystals            With Binder                   With Binder                          With Binder                                 With Binder                                         aloneExample     2    3      9      10     4       11__________________________________________________________________________WHSV, on total       0.4  0.6    0.6    0.6    0.5 0.6 0.5Material BalanceTime, Hrs.  2    15     18     18     19.5                                     18.5                                         2C.sub.3 =  Conversion, wt %       16   15     16     5      77  77  55Yields, wt %C.sub.1 + C.sub.2       0.1  0.5    0.1    --     --  0.3 --C.sub.3 =   84.0 85.5   83.6   95.2   22.7                                     22.6                                         45.4C.sub.3     7.9  13.3   3.3    0.9    2.4 1.8 53.8C.sub.4 + C.sub.5       8.0  0.7    8.2    2.7    3.0 3.0 0.8C.sub.6 +   0.1  0.1    4.8    1.1    71.9                                     72.3                                         --       100.0            100.0  100.0  100.0  100.0                                     100.0                                         100.0330° F. + Distillate% of Liq. Prod.       --   --     --     --     56  --  --__________________________________________________________________________
From the above table, the pure crystals, i.e. Example 2 made no liquid product. The physical mixture, i.e. Example 3, eliminated the possibility that the high silica ZSM-5 and the alumina particles as such are interacting and the dry mulling experiment, i.e. Example 9, eliminates ammonium exchange in the final calcination as being involved in the generation of active sites. The water extract experiment, i.e. Example 10, eliminates room temperature wet mulling as a possible source of dissolved alumina entering the ZSM-5 pores. The alumina only experiment, i.e. Example 11, also made no liquid product and as such this result confirms the fact that the binder as such in the wet mulled catalyst is not making liquid product at 400° F.
EXAMPLE S 12C-14C
TABLE__________________________________________________________________________Example 12      13      14     4__________________________________________________________________________Method of   Dry Mulling.sup.(1)           Wet Mulling.sup.(1)                   Dry Mixing.sup.(2)                          Wet Mulling.sup.(1)Incorporation   and Hand           and Hand                   and Hand                          Hydraulic Extrusion   Pressing           Pressing                   Pressing                          (at 25 ton pressure.sup.(3))Alpha Activity   0.25    1.0     0.13   5.7__________________________________________________________________________ .sup.(1) Mulling  Mix in a muller (Cincinnati Muller Co.) for 10-15 minutes with or without water .sup.(2) Mixing  Mechanical mixing with no kneading action .sup.(3) Extrusions  Extrusion using a hydraulic RAM extruder
EXAMPLE S 15C-16C
TABLE______________________________________Example       15         4      16______________________________________PrecalcinationTemperature, °F.         800        1000   1200Time, Hr.     8          3      3Atmosphere    NH.sub.3   NH.sub.3                           NH.sub.3Alpha Activity         0.5        5.7    3.0______________________________________
EXAMPLE S 17C-18C
TABLE______________________________________Example     17          4       18______________________________________Zeolite/Binder(wt. basis) 90/10       65/35   10/90Alpha activity       0.40        5.7      3.0Alpha activity,Normalized* 0.24        5.7     19.5______________________________________ *Normalized to unit weight of zeolite based on 65/35 wt. ratio.
EXAMPLE S 19C-22C
EXAMPLE 19C Zirconia Binder
As synthesized ultra low Al ZSM-5 zeolite was intimately mixed with a zirconia gel of 25% solution by weight (from duPont Chemical). The weight ratio of ZSM-5 to ZrO2 was adjusted to 65/35. The mixture was then dried and calcined in a NH3 stream at 1000° F. for three hours. The Na content in the material was then exhanged with 1 N NH4 /NO3 solution to reduce to less than 0.05%. The sample was then sized to 14/25 mesh size material and calcined to 1000° F. in air for three hours.
EXAMPLE 20C Titania Binder
EXAMPLE 21C Silica Binder
EXAMPLE 22C Alumina Binder
TABLE______________________________________Example    19      20       21    22     1______________________________________Binder Material      ZrO.sub.2              TiO.sub.2                       SiO.sub.2                             Al.sub.2 O.sub.3                                    NoneZeolite/Binder                           Pure(wt. basis)      65/35                 ZeoliteMethod ofIncorporation      Mortar and Pestle Mix and Hand PressingAlpha Activity      0.72    0.77     0.28  0.51   0.2______________________________________
EXAMPLE S 23C-25C
In each of Examples 23C-25C, the catalyst prepared by the process of Example 4 was ground to different mesh size and the Alpha activity measured.
A 2 g. sample of NaZSM-5/Al2 O3 extrudate (zeolite silica:alumina ratio of 70:1) was found to be essentially inactive, having an alpha value for the zeolite of 0.15. In the hexadecane cracking test, the conversion was less than 1 percent.
A high pour point crude oil (pour point over 15° C.) is passed over a steamed NaZSM-5/Al2 O3 extrudate (65% zeolite, 35% alumina) at 350° C., 1 WHSV in 2170 kPa hydrogen. The dewaxed oil obatined in better than 90% yield is found to have a pour point below -32° C.
A 2-g. sample of ZSM-5 zeolite having a silica-to-alumina ratio of about 26,000 and a sodium content of about 0.23 weight percent was impregnated with 3 grams of 5 weight percent sodium aluminate solution and calcined in air at 538° C. for 20 hours.
A sample of the same ZSM-5 used above was vacuum impregnated with a solution of sodium aluminate which was diluted by an equal volume of concentrated (12N) NH4 OH. The pH was 12.4. After 30 minutes, the sample was dried and submitted to three cycles of 1N NH4 N3 treatment followed by hot water washing. The sample was dried and calcined at 538° C. prior to testing.
The products of Examples 1E-3E were evaluated for alpha activity.
Three different high silica-containing zeolites of ZSM-5 type are treated with a solution which was prepared by dissolving 2.55 grams of sodium hydroxide, 10.0 grams of tetrapropylammonium bromide and 7.2 grams of Al2 (SO4)3 . 14 H2 O and 115 grams of water. The hydro-treating conditions are maintained at 100° C. (212° F.) for 6 hours at 1 atmosphere pressure. The solution to zeolite weight ratio is 3.4 parts of solution per part of zeolite and its pH is 9.9.
Zeolites A and B, having silica-to-alumina ratios of 500 and 1600 are precalcined in nitrogen at 540° C. (1000° F.) for 3 hours prior to treatment. Zeolite C was used as crystallized without pre-calcination. After the three zeolites have been hydrotreated in accordance with the above procedures, they are processed into their active form by calcination in nitrogen at 540° C. (1000° F.), followed by ammonium exchange with an aqueous solution of ammonium nitrate at ambient temperatures to remove excess aluminum ions. Finally, all materials are air calcined at a temperature of 540° C. (1000° F.) for three hours. The three zeolites, before and after treatment, are evaluated for hydrocarbon cracking activity (alpha-value, "α'").
TABLE 1______________________________________Activity of High SiO.sup.2 ZSM-5 After TreatmentMaterial      A         B         C______________________________________Zeolite       ZSM-5     ZSM-5     ZSM-5SiO.sub.2 /Al.sub.2 O.sub.3         500:1     1600:1    30,000:1         Acid      Acid      AcidForm          (Calcined)                   (Calcined)                             (As                             Crystallizedo(Untreated acid form)         10        1.7       0.1T(Treated acid form)         27        15        2.3Enhancement, T/o         2.7       8.8       23______________________________________
COMPARATIVE EXAMPLES 2F-8F
Four grams of type C low Al ZSM-5 (containing 50 ppm Al2 O3) in its NH4 form are impregnated with solution of 0.03 g Al (NO3)3 CH2 O in 2 g water. The wet zeolite mix is dried slowly, slugged and sized into 14/25 mesh. The resultant catalyst is activated at 540° C. (1000° F.) for three hours. The alpha value is 0.38.
Zeolite C catalyst is treated in ammonium form in a manner similar to those described in Example 2 except using 0.15 g Al (NO3)3.9H2 O. The alpha value is 0.56.
Ammonium Zeolite C is treated in a manner similar to Example 2 except using 0.3 g Al (NO3)3.9H2 O. The alpha value is 0.81.
This catalyst is treated in a similar manner to Example 7 except that 1.18 Al2 (OH)5 Cl is used instead of Al (NO3)3.9H2 O. The alpha activity of the catalyst was found to be 0.31.
The results obtained in Examples 2F-8F are shown in Table 2, wherein it is demonstrated that the results obtained are distinctly inferior to the claimed invention as illustrated in Table 1.
TABLE 2__________________________________________________________________________Aluminum Addition to High Silica ZeolitesExample No.   2    3  4  5   6  7    8__________________________________________________________________________Base MaterialZeolite       ZSM-5SiO.sub.2 /Al.sub.2 O.sub.3         30,000Form          NH.sub.4              NH.sub.4                 NH.sub.4                    NH.sub.4                        As CrystallizedTreating Agent         Al(NO.sub.3).sub.3              NaAlO.sub.2  Al(NO.sub.3).sub.3                                Al.sub.2 (OH).sub.5 ClMethod of Treat         Impregnation      EXCH EXCH% Al.sub.2 O.sub.3 Incorporated         0.1  0.5                 2  0.5 0.5                           0.5  0.5(Based on Zeolite)Alpha of H Form Untreated         0.2Treated       0.38 0.56                 0.81                    0.2 0.43                           0.24 0.31__________________________________________________________________________
EXAMPLE S 1G TO 7G
______________________________________Example Temp.No.     (°C.)           Time    Acid Activity (α)                              Notes______________________________________1       165     1 day   41         --2       100     8 days  4.5        --3       170     1 day   33         H.sub.2 O loss4       165     1 day   195        1N.NaOH                              aq. solution5       165     1 day   72         0.2N NaOH                              aq. solution6       25      1 day   0.6        1N.NaOH                              aq. solution7       173     14 hrs. 23         --______________________________________
EXAMPLE S 8G-10G
The above procedure is repeated except that different samples are treated simultaneously in a sealed autoclave at 130° C. for 64 hours and then at 170° C. for 24 hours. Control example 8 contains no alumina and consists of HZSM-5 (α=0.015). Example 9 in an extruded mixture of the particulate zeolite and alpha-alumina monohydrate binder in equal weight portions. Example 10 is an equal mixture of the zeolite with alpha-alumina monohydrate beads slurried with water.
______________________________________Example No.     Alumina   Treatment   Activity (α)______________________________________8         nil       none        0.0159         binder    hydrothermal                           4110        beads     hydrothermal*                           7______________________________________ *Loss of H.sub.2 O indicated. Beads seperated from treated zeolite prior to activity test.
EXAMPLE S 11G TO 15G
The procedure of Example 10 is repeated using an admixture of HZSM-5 and --Al2 O3 beads, except that the standard heating period is 1 day.
______________________________________Example No.      Temp. (°C.)                   Activity Note______________________________________11         165          7        --12         100          0.3      --13         170          2        H.sub.2 O Loss14         165          0.5      Steam Only15         165          81       --N NaOH______________________________________
Examples 11G, 13G and 14G show how hydrothermal treatment in contact with an aqueous liquid can improve activity markedly (14×), as compared to steaming, where the role of water as a transport medium is necessarily restricted. By fully covering the catalyst with water during hydrothermal treatment enhancement is maximized.
EXAMPLE S 16G TO 29G
______________________________________Example No.     Act. Agent Activity (α)                             Note______________________________________16        B.sub.2 O.sub.3                0.8          170°, 0.5 parts17        NaAlO.sub.2                148          0.6 parts18        TiO.sub.2  1.3          0.5 parts19        Fe(NO.sub.3).sub.3                0.3          170°20        B.sub.2 O.sub.3                0.5          0.7 parts21        V.sub.2 O.sub.5 /SiO.sub.2 *                1.4          0.6 parts22        Na.sub.3 PO.sub.4                2.9          0.6 parts23        NH.sub.4 VO.sub.4                0.6          0.5 parts24        K.sub.2 CrO.sub.4                0.9          0.8 parts25        Na.sub.2 B.sub.4 O.sub.7                1.6          0.7 parts26        NaAlO.sub.2                27           0.1 parts                             H.sub.2 O loss27        NaAlO.sub.2                223          0.5 parts28        Na.sub.2 WO.sub.4                1.1          0.7 parts29        Na.sub.2 B.sub.4 O.sub.7                1.1          0.1 parts______________________________________ *Girdler 101 catalyst Kpromoted beads.
__________________________________________________________________________Example No.  Temp °C.       Pressure            Treatment                    Time Cat. Activity__________________________________________________________________________2      100  1 atmo.            Hydrothermal                    8 days                         4.57      173  125 psi            Hydrothermal                    14 hours                         2330     228  1 atmo.            steam   20 hours                         1.6control  --   --   none    --   1.4__________________________________________________________________________
The procedure of Example 1 is repeated except the hydrothermal treatment is conducted at 151° C. for 40 hours, giving an acid activity (α) =33.
The standard hydrotreating procedure is followed except the zeolite employed is a crystalline borosilicate prepared by the method of U.S. Pat. No. 4,269,813 (Klotz). The zeolite is treated in admixture with alpha-Al2 O3 monohydrate beads at 205° C. for 18 hours. The cracking activity (α) of the zeolite is increased from 7 to 12.
EXAMPLE S 1H TO 7H
The ammonium form of a sample of ZSM-5 having a silica to alumina ratio of 26000:1 and hexane cracking activity (alpha value) of 0.02 (65 parts by weight) is wet milled with alpha alumina monohydrate (35 parts) and extruded into cylindrical pellets having a diameter of about 2mm., dried and calcined. Samples of this material are covered with water or sodium hydroxide solution in an open tube and maintained at different temperatures for varying amounts of time. For temperatures above 100° C., an autoclave was used. The apparatus employed comprises a steel autoclave equipped with temperature and pressure measuring devices and an internal sample support for holding open top test tubes, during treatment. A quantity of water is contained in the autoclave bottom, with test tubes being suspended in the liquid water. During the treatment the autoclave is heated to treatment temperature. The water vaporizes to form a saturated gas phase in equilibrium with the liquid phase at elevated temperature. The activated extrudate samples were recovered, post-treated with ammonium nitrate to base-exchange the catalyst, and calcined at 540° C. to convert them to the hydrogen form. The catalytic activity for cracking hexane (alpha activity) was then measured. The results are tabulated below:
TABLE I______________________________________                        AlphaExample No.     Temp. (°C.)                Time    Activity                               Notes______________________________________1         165        1 day   41     Water2         100        8 days  4.5    Water3         170        1 day   33     Water4         165        1 day   195    1N NaOH5         165        1 day   72     0.2N NaOH6          25        1 day   0.6    1N NaOH7         173        14 hrs. 23     Water______________________________________
EXAMPLE S 8H-10H
The above procedure is repeated except that different samples are treated simultaneously in the sealed autoclave at 130° C. for 64 hours and then at 170° C. for 24 hours. Control example 8 contains no alumina and consists of HZSM-5 (alpha =0.015). Example 9 in an extruded mixture of the particulate zeolite and alpha-alumina monohydrate binder in equal weight portions. Example 10 is an equal mixture of the zeolite with gamma alumina bead slurried with water. Loss of water during treatment was noted in Example 10 because the product, on removal, was dry. The results are shown in Table II.
EXAMPLE S 11H TO 15H
TABLE III______________________________________                AlphaExample No.     Temp. (°C.)                Activity  Note______________________________________11        165        7         Water12        100        0.3       Water13        170        2         Water14        165        0.5       Steam Only15        165        81        1-N NaOH Solution______________________________________
EXAMPLE S 16H TO 18H
Portions of the same zeolite as that used in Example 1 were wet mulled with sodium aluminate, placed in test tubes, and treated in an excess of water at 165° C. in the autoclave.
The parts by weight of sodium aluminate per part of zeolite were as shown in Table IV. Example 17 lost water during treatment.
TABLE IV______________________________________                   AlphaExample No.      Act. Agent   Activity Note______________________________________16         NalO.sub.2   148      0.6 parts17         NaAlO.sub.2   27      0.1 parts18         NaAlO.sub.2  223      0.5 parts______________________________________
A 2-gram sample of HZSM-5 extrudate that contained 35 wt% alumina and 65 wt% zeolite with a silica to alumina ratio of 70:1, and having an alpha value of about 225, was refluxed for 3 hours with 0.2 N NaOH, washed, exchanged with 1N NH4 N3 as in Example 19, dried and tested for hexane cracking activity. The alpha value was 275.
TABLE V______________________________________        Example 24 Example 25______________________________________Conversion (based on          0.5%         94%--CH.sub.2 -- content)Normalized ProductDistribution, %C.sub.1 -C.sub.5 Paraffins          67.7         31.1 C.sub.2 -C.sub.5Olefins        18.8         17.4C.sub.6 + Aliphatics        24.3Aromatics                   27.2Coke           13.5         less than 0.1______________________________________
EXAMPLE S 26H-30H
The treated extrudates were tested for n-hexane cracking activity. Results are plotted in FIG. 1 as alpha vs NaOH concentration. The starting material had an alpha =0.02 (based on zeolite content). It is seen from FIG. 1 that with increasing NaOH concentration, alpha increased to 450 at 0.2 N NaOH, and drops back to 1.2 at 1N NaOH. The Constraint Index (CI) of the highest activity sample was found to be 7.9.
Examination of the product of Example 28 (alpha =450) showed the zeolite to be 71% crystalline compared with the untreated extrudate (100% crystalline), and to display ortho- rhombic symmetry characteristic of ZSM-5 material with relatively low silica to alumina ratio. Sorption of 2-2 dimethylbutane was slightly diminished, consistent with crystallinity.
The same extrudate as used in Examples 26-30 was treated at room temperature overnight with 0.2 N NaOH. The product, after exchange with ammonium salt and calcination, had an alpha value of 14.
5.0 g NH4 -ZSM-5C (LDR-773-1-1B), binder-free, was added to 50 g 1 M aqueous NaOH contained in a polypropylene bottle. The mixture was allowed to stand at room temperature for 24 hours, and was then heated at 62° C. for ;70 additional hours. The mixture was cooled, filtered, washed well, and dried. The recovered solid was 1.62 g; 67.8% of the original material had dissolved. The x-ray pattern indicated the presence of ZSM-5 in teh recovered solid.
Initial zeolite:
Si/Al2 (by elemental analysis) =74.6
Alpha (hexane cracking activity) =77
NH4 + exchange capacity (meq/g ash) =0.43
Product zeolite:
Si/Al2 (by elemental analysis) =16.6
Na/Al (by elemental analysis) =1.0
NH4 + exchange capacity (meq/g ash) =1.22 (equivalent in Si/Al2 of 25.7)
Alpha (hexane cracking activity) =322
3.0 g NH4 -ZSM-5B (JAM-1086-11-1B), binder-free, was added to 100 ml 0.4 M aqueous NaOH contained in a polypropylene bottle. The mixture was shaken continuously at room temperature for 66 hours. After filtration and drying, the recovered solid was 0.9 g, indicating 70.5% of the original zeolite had dissolved. XRD confirmed the presence of ZSM-5 in the recovered solid.
Si/Al2 (by elemental analysis) =66.7
Alpha (hexane cracking activity) =130
NH4 + exchange capacity (meq/g ash) =0.45
Si/Al2 (by elemental analysis) =16.0
Na/Al (by elemental analysis) =1.1
NH4 exchange capacity =0.88 (equivalent to Si/Al2 of 38)
Alpha (hexane cracking activity) =311
ZSM-5 crystals with SiO2 /Al2 O3 =70/1 calcined and free of binder was treated with Na2 CO3 (0.5M) solution at refluxing temperature for 20 hours. The treated material was then NH4 + exchange. The zeolite was then calcined at 538° C. and tested for n-hexane cracking activity. The alpha increased from 328 to 825.
EXAMPLE S 2K and 3K
ZSM-5 with SiO2 /Al2 O3 =70/1 calcined and free fo binder was treated with Na2 CO3 /NaNO3 (0.5M/0.6M) solution at refluxing temperature for 2 hours and 20 hours. The treated material was then NH4 + exchange. The zeolite was then calcined at 538° C. and tested for n-hexane cracking activity. Table 1 shows after 2 and 20 hours of treatment, the SiO2 /Al2 O3 ratio (calculated from NH4 + TPD measurement) changes from 70/1 to 38/1 and 29/1 with respectively. The alpha changes from 328 to 420 and 1134 with respectively.
ZSM-5 with SiO2 /Al2 O3 =850/1 was treated with Na2 CO3 /NaNO3 (0.5M/0.6M) solution at refluxing temperatures for 20 hours. Table 2 shows the SiO2 /Al2 O3 ratio increases from 850/1 to 48/1 and alpha increases from 4 to 1087.
TABLE 1______________________________________Examples 2K and 3KTreatment time        Parent     2 Hrs.    20 Hrs.______________________________________Catalyst no. CTC-116    CTC-382   CTC-365NH.sub.4.sup.+  TPD        0.4597     0.8398    1.0767(meq/g ash)SiO.sub.2 /Al.sub.2 O.sub.3        71/1       38/1      29/1alpha        328        420       1134______________________________________
TABLE 2______________________________________Example 4         Parent     20 Hrs.______________________________________Catalyst no.    CTC-362      CTC-374NH.sub.4.sup.+  TPD           0.0391       0.6656(meq/g ash)SiO.sub.2 /Al.sub.2 O.sub.3           850/1        48/1alpha           4            1087______________________________________
Although in the preceeding examples extensive use was made of alumina as the preferred added activating metal oxide, it is to be understood that other metal or non-metal oxides which contain an element capable of being incorporated in the zeolite as a minor robust framework element are also contemplated as within the scope of this invention. Illustrative of such elements are gallium and iron as well as the other elements indicated by example as effective.
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U.S. Classification 502/71, 502/77, 502/85
International Classification B01J29/70, B01J29/65, B01J29/40
Cooperative Classification B01J29/40, B01J29/70, B01J2229/26, B01J2229/36, B01J2229/42, B01J29/7007, B01J29/65
European Classification B01J29/40, B01J29/70B