Catalytic oxidative process for producing maleic anhydride

Unsaturated hydrocarbons having 4 to 6 carbon atoms are catalytically oxidized into maleic anhydride by using a catalyst, which consists essentially of oxides of (A) vanadium, (B) phosphorus, (C) titanium and (D) optionally at least one element selected from sodium, calcium, magnesium, iron, zirconium, boron, manganese, silver and molybdenum in the atomic ratios defined by the following formula EQU VP.sub.a Ti.sub.b X.sub.c O.sub.d wherein X is the element (D) set forth above and a=1.0 to 5.0, b=2.0 to 12.0 and c=0 to 1.0, and which catalyst is prepared by calcining a mixture of a vanadium-containing compound and titanium dioxide at a temperature of 650.degree. C. to 1,500.degree. C., incorporating into the mixture a phosphorus-containing compound and optionally the element "X"-containing compound and, then, heating the resulting mixture.

This invention relates to a process for producing maleic anhydride by 
contacting in the vapor phase a feed mixture comprising an unsaturated 
hydrocarbon having 4 to 6 carbon atoms and oxygen with a catalyst 
exhibiting an improved activity. 
Many proposals have been heretofore put forth for the production of maleic 
anhydride, which comprise catalytically oxidizing an unsaturated 
hydrocarbon having four to six carbon atoms such as n-butene, 
1,3-butadiene, benzene or cyclopentadiene or a hydrocarbon mixture 
containing such an unsaturated hydrocarbon having 4 to 6 carbon atoms. 
Some typical processes have been carried out using a catalyst consisting 
of oxides of vanadium, phosphorus and titanium. For example, Japanese 
Patent Publication No. 7888/1965 discloses catalysts which consist of a 
vanadium oxide and a phosphorus oxide, the substantial part of said 
vanadium having a valency of less than 5. It is mentioned that these 
catalysts optionally contain as a cocatalyst a minor amount of another 
metal oxide such as an oxide of titanium, chromium, cobalt, nickel, zinc, 
zirconium, tin, antimony, bismuth or thorium. 
Japanese Patent Publication No. 7737/1962 discloses a catalyst comprising 
anatase-type titanium dioxide particles covered with vanadium pentoxide or 
a mixture of vanadium pentoxide and potassium sulfate. Japanese Patent 
Publication No. 39845/1971 discloses a catalyst consisting essentially of 
vanadium pentoxide, titanium dioxide and at least one oxide or another 
compound of aluminum, lithium and zirconium. Japanese Patent Laid-open 
Application No. 62719/1973 discloses a catalyst consisting of vanadium 
pentoxide, phosphorus pentoxide, anatase-type titanium dioxide and 
optionally tungsten trioxide and/or molybdenum trioxide. It is to be noted 
that titanium dioxide present in these catalysts is of an anatase-type 
structure. 
The above-mentioned known catalysts are not satisfactory because the yield 
of or selectivity to maleic anhydride is not attractive. 
A main object of the present invention is to provide a process for 
effecting vapor phase oxidation of an unsaturated hydrocarbon having 4 to 
6 carbon atoms, which makes it possible to produce maleic anhydride with 
improved yield. 
Another object of the present invention is to provide a catalyst exhibiting 
improved activity for the vapor phase oxidation of an unsaturated 
hydrocarbon having 4 to 6 carbon atoms into maleic anhydride. 
These and other objects and advantages of the present invention will become 
clear from the following description. 
In accordance with the present invention, there is provided a process for 
producing maleic anhydride by catalytic oxidation of an unsaturated 
hydrocarbon having 4 to 6 carbon atoms, which comprises contacting a 
feed-gas mixture comprising said unsaturated hydrocarbon and oxygen in the 
vapor phase with a catalyst consisting essentially of oxides of (A) 
vanadium, (B) phosphorus, (C) titanium and (D) at least one element 
selected from the group consisting of sodium, calcium, magnesium, iron, 
zirconium, boron, manganese, silver and molybdenum, in the atomic ratios 
defined by the following formula 
EQU VP.sub.a Ti.sub.b X.sub.c O.sub.d 
wherein X is at least one element selected from the above group, and each 
of a, b and c is a positive number indicating an atomic ratio of each of 
the (B), (C) and (D) to vanadium and falling within the following ranges, 
a=1.0 to 5.0, preferably 2.0 to 4.0, b=2.0 to 12.0, preferably 4.5 to 
10.0, and c=0 to 1.0, preferably0.05 to 1.0, and d is a positive number 
satisfying the average valency of the (A), (B), (C) and (D), and being 
within the range from 8 to 40; said catalyst being prepared by calcining a 
mixture of a vanadium-containing compound and titanium dioxide at a 
temperature of 650.degree. C. to 1,500.degree. C., incorporating into the 
mixture a phosphorus-containing compound and optionally a compound 
containing the element "X" set forth above and, then, heating the 
resulting mixture. 
The catalyst used in the process of the invention is characterized as, 
first, possessing a composition such that the respective components (A), 
(B), (C) and (D), set forth above, are present therein in the atomic 
ratios defined by the above formula, and; second, being prepared by the 
process comprising calcining a mixture of a vanadium-containing compound 
and titanium dioxide at a temperature of 650.degree. C. to 1,500.degree. 
C., incorporating into the mixture a phosphorus-containing compound and 
optionally a compound containing the element "X" set forth above and, 
then, heating the resulting mixture. 
The amount of phosphorus present in the catalyst should be such that the 
atomic ratio of phosphorus to vanadium falls within the range of 1.0 to 
5.0, preferably 2.0 to 4.0. The selectivity to maleic anhydride increases 
with an increase of the atomic ratio (P/V) of phosphorus to vanadium, but 
steeply decreases when the atomic ratio (P/V) exceeds approximately 5.0. 
The catalyst activity increases gradually with a decrease of the atomic 
ratio P/V, but maleic anhydride produced is undesirably oxidatively 
decomposed and the selectivity to maleic anhydride decreases when the 
atomic ratio P/V becomes lower than approximately 1.0. The amount of 
titanium should be such that the atomic ratio (Ti/V) of titanium to 
vanadium falls within the range of 2.0 to 12.0, preferably 4.5 to 10.0. 
The catalyst activity decreases with an increase of the atomic ratio 
(Ti/V) of titanium to vanadium and the yield of maleic anhydride decreases 
steeply when the atomic ratio (Ti/V) exceeds approximately 12.0. The yield 
of maleic anhydride becomes low also when the atomic ratio (Ti/V) is lower 
than approximately 2.0. 
The atomic ratio (X/V) of the element "X" to vanadium may be varied within 
the range of 0 to 1.0, preferably 0.05 to 1.0. The incorporation of the 
element "X" is optional. However, it is advantageous to use a minor amount 
of the element "X", because the reaction temperature at which maleic 
anhydride is obtained with the maximum yield, i.e. the lowest reaction 
temperature at which the conversion of the unsaturated hydrocarbon is 
100%, can be lowered thereby without the reduction in yield of maleic 
anhydride. The low reaction temperature is advantageous in that 
undesirable thermal decomposition is suppressed and it is easy to 
precisely control the reaction temperature. However, when the atomic ratio 
(X/V) is in excess of approximately 1.0, the yield of maleic anhydride 
decreases to an appreciable extent. 
The process whereby the catalyst of the invention is prepared is critical. 
That is, a mixture of a vanadium-containing compound and titanium dioxide 
should be calcined at a temperature of 650.degree. C. to 1,500.degree. C. 
prior to incorporation of a phosphorus-containing compound and an optional 
element X-containing compound. The calcination of the aforesaid mixture is 
preferably carried out at 650.degree. to 1,100.degree. C., more preferably 
650.degree. to 900.degree. C. The period of time for the calcination may 
be 30 minutes to several hours, usually 30 minutes to 2 hours. 
The titanium dioxide to be blended with a vanadium-containing compound may 
be either of an anatase-type structure or of a rutile-type structure. The 
structure of titanium dioxide present in the calcined mixture is rutile 
whether it is anatase or rutile before the calcination. That is, when 
anatase titanium dioxide is calcined at the aforesaid temperature, it is 
converted to rutile-type titanium dioxide. It can readily be recognized by 
X-ray diffractiometry whether the structure of titanium dioxide is anatase 
or rutile. It is to be noted that anatase-type titanium oxide can readily 
be converted to rutile-type titanium dioxide even at a temperature on the 
order of 650.degree. C. or so in the presence of a vanadium-containing 
compound, although it is known that anatase-type titanium dioxide can be 
converted to rutile at approximately 900.degree. C. or more in the absence 
of a vanadium-containing compound. It should be especially noted that the 
catalyst of the present invention exhibits improved yield of maleic 
anhydride as compared with a catalyst prepared by a procedure similar to 
that defined in the present invention except that the calcination is 
carried out at a temperature lower than 650.degree. C. 
When the calcination at a temperature of 650.degree. C. to 1,500.degree. C. 
is carried out after blending the mixture of a vanadium-containing 
compound and titanium dioxide with a phosphorus-containing compound and 
optionally an element X-containing compound, it becomes difficult to 
obtain the desired catalyst because the phosphorus sublimes and flies away 
to some extent. 
The mixture of a vanadium-containing compound and titanium dioxide may be 
prepared in a known manner, for example, by a wet process wherein a 
vanadium compound and a titanium dioxide are mixed with each other 
together with water followed by drying or a dry process wherein the two 
finely divided materials are blended with each other without water. 
The compounds for the preparation of the catalyst may be oxides, acids or 
salts, or a mixture thereof. Illustrations of the vanadium-containing 
compounds are oxides such as vanadium pentoxide, vanadium trioxide, 
vanadium dioxide, vanadium monoxide and metavanadic acid; and salts such 
as vanadous chloride, vanadic chloride, vanadium tetrachloride, vanadium 
oxychloride and ammonium metavanadate. Of these compounds, vanadium 
pentoxide and ammonium metavanadate are preferable. Particularly vandadium 
pentoxide is optimum because weight loss is low and no toxic gas evolves 
when calcined. 
Illustrations of the phosphorus-containing compounds are oxides such as 
phosphorus pentoxide, phosphorus tetraoxide and phosphorus trioxide; 
phosphates such as ammonium phosphate; and acid such as orthophosphoric 
acid and triphosphoric acid. 
Illustrations of the element "X"-containing compounds are, for 
sodium-containing compounds, sodium oxide, sodium hydroxide, sodium 
nitrate, sodium sulfate and sodium carbonate; for calcium-containing 
compounds, calcium oxide, calcium hydroxide, calcium nitrate, calcium 
sulfate, calcium carbonate and calcium oxalate; for magnesium-containing 
compounds, magnesium oxide, magnesium hydroxide, magnesium nitrate, 
magnesium sulfate and magnesium carbonate; for iron-containing compounds, 
ferric oxide, ferrosoferric oxide, ferrous hydroxide, ferric hydroxide, 
ferrous nitrate, ferric nitrate and ferrous sulfate; for 
zirconium-containing compounds, zirconium oxide, zirconium nitrate, 
zirconyl nitrate [ZrO(NO.sub.3).sub.2 ] and zirconium sulfate; for 
boron-containing compounds, boron trioxide and boric acid; for 
manganese-containing compounds, manganese dioxide, manganese nitrate, 
manganese carbonate and manganese oxalate; for silver-containing 
compounds, silver oxide, silver nitrate and silver carbonate; and, for 
molybdenum-containing componunds, molybdenum dioxide, molybdenum oxide and 
ammonium molybdate [(NH.sub.4)MoO.sub.4 and (NH.sub.4).sub.6 Mo.sub.7 
O.sub.24 ]. 
The materials, i.e. (1) the calcined mixture of the vanadium-containing 
compound and titanium dioxide, (2) the phosphorus-containing compound, and 
(3) the optional element "X"-containing compound, may be blended in a 
known manner; for example, by a wet process wherein the above three 
materials are mixed with each other in the form of solution and/or 
dispersion in a solvent, followed by removal of the solvent, or by a dry 
process wherein the above three materials are mixed with each other 
without use of the solvent. The prepared mixture of the above three 
materials is then heated generally at a temperature of 300.degree. C. to 
600.degree. C., preferably 400.degree. C. to 600.degree. C. and for a 
period of 1 to 10 hours to obtain a catalyst. The catalyst is very hard. 
The catalyst may be pulverized and shaped into pellets or particles of 
desired shape and size. Alternatively, the mixture of the above three 
materials may be pulverized and/or shaped into pellets or particles of 
desired shape and size prior to the heating. 
Unsaturated hydrocarbons having four to six carbon atoms which are used as 
a starting material in the process of the invention include, for example, 
aliphatic unsaturated hydrocarbons such as n-butene-1, n-butene-2 and 
1,3-butadiene; alicyclic unsaturated hydrocarbons such as cyclopentadiene; 
and benzene. Of these, aliphatic straight chain unsaturated hydrocarbons 
are preferable. The unsaturated hydrocarbon used may be a hydrocarbon 
mixture containing at least approximately 20% by mole, preferably at least 
approximately 40% by mole, of one or more of the aforesaid unsaturated 
hydrocarbons of four to six carbon atoms. Suitable mixtures include, for 
example, a C.sub.4 -fraction produced in the course of catalytical 
cracking of petroleum naphtha, and a butane-butene fraction (B-B fraction) 
or spent B-B, i.e. a residue produced when 1,3-butadiene is extracted from 
the C.sub.4 -fraction. 
As a source of oxygen which is used in the catalytic oxidation reaction of 
the invention, pure oxygen and an oxygen-containing gas such as air may be 
used. Particularly, air may be advantageously used. A relative proportion 
of oxygen in the feed-gas mixture is suitably from about 10 to about 200 
moles per mole of the unsaturated hydrocarbon. In general, the unsaturated 
hydrocarbon and oxygen is diluted with an inert diluent gas such as 
nitrogen in order to avoid the risk of explosion. For example, the 
unsaturated hydrocarbon is advantageously diluted so that the resulting 
feed mixture contains 2% by volume or less preferably 0.1 to 1.5% by 
volume, of the unsaturated hydrocarbon. 
Although the optimum reaction temperature varies to some extent depending 
upon the composition of the catalyst employed, the reaction temperature 
may be varied perferably within the range of 330.degree. C. to 475.degree. 
C., more preferably 350.degree. C. to 450.degree. C. The contact time may 
be varied preferably within the range of 0.2 to 1.8 seconds, more 
preferably 0.3 to 1.5 second. 
The catalyst may be used alone or in combination with any of the known 
carriers. As carriers, those which bring favorable effects for the 
reaction involved, such as silica, alumina, and alumina-silica, which have 
been deactivated by, e.g. heat-treatment, may suitably be employed. The 
catalyst may be employed in either a fluidized bed or a fixed bed. 
In practice, high yields of maleic anhydride are obtained. Saturated acids 
such as acetic acid are produced only in trace amounts. No detectable 
amounts of aldehydes are produced. The invention is further illustrated by 
the following examples and comparative examles, which are for purposes of 
illustration only and should not be construed as limiting the invention in 
any sense. In these examples, conversion and yield were calculated by the 
following equations. 
##EQU1## 
where MA is maleic anhydride and UHC is the unsaturated hydrocarbon having 
4 to 6 carbon atoms employed. The yield used herein means a one pass yield 
.

EXAMPLE 1 
A mixture of 5.4 g of a finely divided vanadium pentoxide powder and 45 g 
of a finely divided anatase-type titanium dioxide powder was calcined at 
700.degree. C. for one hour, thereby to obtain a dark purple powder. To 50 
g of the dark purple powder, 13.6 g of an aqueous orthophosphoric acid and 
a minor amount of water were added. The mixture was ground down by using a 
kneader, dried at 110.degree. C. and, then, maintained at 500.degree. C. 
in the air for 5 hours. The obtained lump was pulverized and dressed into 
10 to 20 mesh. 
The catalyst so prepared was dark purple and had a composition such that 
the atomic ratios of P/v and Ti/v were 2.0 and 9.5, respectively. The 
titanium oxide present in the catalyst proved by X-ray diffractiometry to 
be of a rutile-type structure. 
A feed-mixture of 0.5% by volume of butene-1 and 99.5% by volume of air was 
passed through a reactor packed with the above-mentioned catalyst and 
maintained at 450.degree. C. The contact time was 0.6 second. The 
conversion of butene-1 and the yield of maleic anhydride and saturated 
acids are shown in Table I, below. 
EXAMPLES 2 THROUGH 4 
Following the procedure set forth in Example 1, maleic anhydride was 
prepared wherein 1,3-butadiene (in Example 2) and a B-B fraction (in 
Examples 3 and 4) were separately used instead of butene-1. The B-B 
faction used had the following composition. 
______________________________________ 
(in % by mole) 
______________________________________ 
Isobutane 0.68 
n-Butane 3.59 
Butene-1* 11.04 
Isobutene 27.15 
Butene-2* 7.91 -1,3-Butadiene* 47.37 
______________________________________ 
*Effective ingredients, the total amount of which is 66.32% by mole. 
In Examples 3 and 4, the reaction temperature was 470.degree. C. and 
450.degree. C., respectively, and the content of the B-B fraction in the 
feed mixture was 1.2% by mole and 0.5% by mole, respectively. All other 
conditions remained substantially the same. Results are shown in Table I, 
below. 
EXAMPLES 5 and 6 
Following the procedure set forth in Example 1, a catalyst was prepared 
wherein rutile-type titanium dioxide was used instead of anatase-type 
titanium dioxide, with all other conditions remaining substantially the 
same. 
Using the aforesaid catalyst, maleic anhydride was prepared from butene-1 
(in Example 5) and 1,3-butadiene (in Example 6), respectively, under 
conditions similar to those employed in Example 1. Results are shown in 
Table I, below. 
EXAMPLES 7 AND 8 
7.7 g of ammonium metavanadate were added to 200 ml of water and, while 
being stirred, heated to dissolve the metavanadate in water. To the 
aqueous solution, 12.4 g of oxalic acid were added, thereby to reduce the 
vanadium and, then, 50 g of anatase-type titanium dioxide were added. The 
mixture was evaporated to dryness by heating it in a water bath. The dried 
product was calcined at 700.degree. C. in the air for one hour to obtain a 
dark purple powder. To 45 g of this powder, 13.7 g of an aqueous 
orthophosphoric acid and minor amount of water were added. The mixture was 
ground down by using a kneader, dried at 110.degree. C., and, then, 
maintained at 500.degree. C. in the air for 5 hours. The catalyst so 
prepared had a composition such that the atomic ratios of P/v and Ti/v 
were 2.0 and 9.5, respectively. 
Using the aforesaid catalyst, maleic anhydride was prepared from butene-1 
(in Example 7) and 1,3-butadiene (in Example 8), respectively, under 
conditions similar to those employed in Example 1. Results are shown in 
Table I, below. 
EXAMPLES 9 AND 10 
Following the procedure set forth in Examples 7 and 8, a catalyst was 
prepared wherein rutile-type titanium dioxide was used instead of 
anatase-type titanium dioxide, with all other conditions remaining 
substantially the same. 
Using the aforesaid catalyst, maleic anhydride was prepared from butene-1 
(in Example 9) and 1,3-butadiene (in Example 10), respectively, under 
conditions similar to those employed in Example 1. Results are shown in 
Table I, below. 
COMATIVE EXAMPLES 1 AND 2 
These comparative examples illustrate the use of a catalyst prepared by 
calcining a mixture of vandium pentoxide and anatase-type titanium dioxide 
at a temperature lower than the claimed range. 
Following the procedure set forth in Example 1, a catalyst was prepared 
wherein the mixture of vanadium pentoxide and anatase-type titanium 
dioxide was calcined at 600.degree. C. instead of 700.degree. C. with all 
other conditions remaining substantially the same. The catalyst so 
prepared was grayish green, and the titanium dioxide present therein 
proved by X-ray diffractiometry to be of an anatase-type structure. 
Using the aforesaid catalyst, maleic anhydride was prepared from butene-1 
(in Comparative Example 1) and 1,3-butadiene (in Comparative Example 2), 
respectively, under substantially the same conditions as those in Example 
1 except that the reaction temperature was varied to 425.degree. C. 
Results are shown in Table I, below. 
COMATIVE EXAMPLES 3 AND 4 
These comparative examples illustrate the use of a catalyst prepared by 
calcining of a vanadium pentoxide and rutile-type titanium dioxide mixture 
at a temperature lower than the claimed range. 
Following the procedure set forth in Comparative Example 1, a catalyst was 
prepared wherein rutile-type titanium dioxide was used instead of 
anatase-type titanium dioxide, with all other conditions remaining 
substantially the same. 
Using the aforesaid catalyst, maleic anhydride was prepared from butene-1 
(in Comparative Example 3) and 1,3-butadiene (in Comparative Example 4), 
respectively, under conditions similar to those employed in Comparative 
Example 1. Results are shown in Table I, below. 
COMATIVE EXAMPLE 5 
This comparative example illustrates the use of a catalyst prepared without 
calcination of a mixture of vanadium pentoxide and anatase-type titanium 
dioxide. 
Following the procedure set forth in Example 1, a catalyst was prepared 
wherein the mixture of vanadium pentoxide and anatase-type titanium 
dioxide was not calcined with all other conditions remaining substantially 
the same. 
Using the aforesaid catalyst, maleic anhydride was prepared from a B-B 
fraction similar to that used in Examples 3 and 4 under substantially the 
same conditions as those in Example 1, except that the content of the B-B 
fraction in the feed mixture was 1.2% by volume. Results are shown in 
Table I, below. 
COMATIVE EXAMPLES 6 AND 7 
These comparative examples illustrate the use of a catalyst prepared from a 
mixture of vanadium pentoxide and rutile-type titanium dioxide without 
calcination of the mixture. 
Following the procedure set forth in Example 1, a catalyst was prepared 
wherein rutile-type titanium dioxide was used instead of anatase-type 
titanium dioxide and the calcination at 700.degree. C. of the mixture of 
rutile-type titanium dioxide and vanadium pentoxide was not carried out, 
with all other conditions remaining substantially the same. 
Using the catalyst so prepared, maleic anhydride was prepared from butene-1 
(in Comparative Example 6) and 1,3-butadiene (in Comparative Example 7) in 
a manner similar to that in Example 1, except that the reaction 
temperature was varied to 425.degree. C. Results are shown in Table I, 
below. 
EXAMPLES 11 AND 12 
These examples illustrate the use of a catalyst prepared by calcining a 
mixture of vanadium pentoxide and anatase-type titanium dioxide at a 
varied temperature. 
Following the procedure set forth in Example 1, a catalyst was prepared 
wherein the mixture of vanadium pentoxide and anatase-type TiO.sub.2 was 
calcined at 650.degree. C. (in Example 11) and 750.degree. C. (in Example 
12) instead of 700.degree. C., with all other conditions remaining 
substantially the same. 
Using the catalyst so prepared, maleic anhydride was prepared in a manner 
similar to that in Example 1, except that 1,3-butadiene was used instead 
of butene-1. Results are shown in Table I, below. 
COMATIVE EXAMPLES 8 AND 9 
These comparative examples illustrate the use of a catalyst prepared by 
using a reduced vanadium and not calcining the mixture of the vanadium 
oxide and anatase-type titanium dioxide. 
7.7 g of ammonium metavanadate were added to 200 ml of water and, while 
being stirred, and the mixture was heated to dissolve the metavanadate in 
the water. To the aqueous solution, 12.4 g of oxalic acid were added to 
thereby reduce the vanadium and, then, 15.2 g of an aqueous 85% 
orthophosphoric acid and 50 g of anatase-type titanium dioxide were added. 
The mixture was graduated by heating to obtain a paste. The paste was 
dried at 110.degree. C., and, then, maintained at 500.degree. C. in the 
air for 5 hours. 
The catalyst so prepared was grayish green and had a composition such that 
the atomic ratios of P/V and Ti/V were 2.0 and 9.5, respectively. The 
titanium oxide present in the catalyst proved by X-ray diffractiometry to 
be of an anatase structure. 
Using the aforesaid catalyst, maleic anhydride was prepared from butene-1 
(in Comparative Example 8) and 1,3-butadiene (in Comparative Example 9) 
under substantially the same conditions as those in Example 1, except that 
the reaction temperature was 425.degree. C. Results are shown in Table I. 
Table 1 
__________________________________________________________________________ 
Reaction Yield 
Calcination 
tem- Maleic 
Saturated 
Example 
Hydrocarbon 
temperature 
perature 
Conversion 
anhydride 
acids 
No. fed (.degree. C.) 
(.degree. C.) 
(%) (%) (%) 
__________________________________________________________________________ 
1 Butene-1 
700 450 100 55.2 1.8 
2 1,3-Butadiene 
700 450 100 66.8 0.8 
3 B-B fraction 
700 470 96.4 36.7 2.0 
(55.7*) 
4 B-B fraction 
700 450 96.3 39.3 2.2 
(59.3*) 
5 Butene-1 
700 450 100 55.0 1.9 
6 1,3-Butadiene 
700 450 100 65.5 0.8 
7 Butene-1 
700 450 100 56.0 1.8 
8 1,3-Butadiene 
700 450 100 66.4 0.6 
9 Butene-1 
700 450 100 54.2 1.8 
10 1,3-Butadiene 
700 450 100 64.8 0.8 
11 1,3-Butadiene 
650 450 100 66.0 0.8 
12 1,3-Butadiene 
750 450 100 65.8 0.8 
Com. 1 
Butene-1 
600 425 100 48.0 1.0 
Com. 2 
1,3-Butadiene 
600 425 100 58.0 0.8 
Com. 3 
Butene-1 
600 425 100 48.6 1.9 
Com. 4 
1,3-Butadiene 
600 425 100 58.1 0.8 
Com. 5 
B-B fraction 
-- 450 96.1 29.0 2.0 
(43.7*) 
Com. 6 
Butene-1 
-- 425 100 48.3 1.2 
Com. 7 
1,3-Butadiene 
-- 425 100 58.1 0.9 
Com. 8 
Butene-1 
-- 425 100 50 1.2 
Com. 9 
1,3-Butadiene 
-- 425 100 59.9 0.8 
__________________________________________________________________________ 
*Yield calculated based on the total amount of the effective ingredients 
present in the BB fraction. 
EXAMPLES 13 THROUGH 16 AND COMATIVE EXAMPLES 10 THROUGH 14 
These examples and comparative examples illustrate the use of catalysts 
containing V, P and Ti in various amounts. 
Following the procedure set forth in Example 1, catalysts were prepared 
wherein the amounts of anatase-type titanium dioxide and orthophosphoric 
acid were varied, with all other conditions remaining substantially the 
same. The catalysts so prepared had the compositions shown in Table II, 
below. The titanium oxide present in the catalysts was all of a 
rutile-type structure. 
Using each of the aforesaid catalysts, maleic anhydride was prepared in a 
manner similar to that set forth in Example 1, except that 1,3-butadiene 
was used instead of butene-1 and the reaction temperature was varied as 
shown in Table II. Results are shown in Table II. 
Table II 
______________________________________ 
Yield 
Atomic Reaction Com- Maleic Saturated 
Example 
ratio temp. version 
anhydride 
acids 
No. V P Ti (.degree. C.) 
(%) (%) (%) 
______________________________________ 
13 1 1 9.5 425 100 62.4 0.2 
14 1 5 9.5 450 100 66.0 0.8 
15 1 2 2 450 100 63.2 0.8 
16 1 2 12 450 100 65.0 0.7 
Com. 10 
1 0.5 9.5 350 100 30.2 0.2 
Com. 11 
1 0.5 9.5 450 100 25.0 0.1 
Com. 12 
1 6 9.5 475 100 55.3 2.0 
Com. 13 
1 2 1 425 100 50.3 1.0 
Com. 14 
1 2 13 450 98 50.0 1.0 
______________________________________ 
EXAMPLES 17 THROUGH 28 
These examples illustrate the use of catalysts containing V, P, Ti and 
another metal (X). 
Following the procedure set forth in Example 1, catalysts were prepared 
wherein various metal (X)-containing compounds shown in Table III, below, 
were separately added together with the aqueous 85% orthophosphoric acid 
to the calcined mixture of vanadium pentoxide and titanium dioxide, with 
all other conditions remaining substantially the same. 
Each catalyst was dark purple and had a composition such that the atomic 
ratios of P/V, Ti/V and X/V were 2.0, 9.5 and 0.1, respectively. The 
titanium dioxide present in each catalyst proved by x-ray diffractiometry 
to be of a rutile-type structure. 
Using each catalyst, maleic anhydride was prepared from butene-1 (in 
Examples 17 through 27) and 1,3-butadiene (in Example 28) under 
substantially the same conditions as those in Example 1, except that the 
reaction temperature was varied as shown in Table III. Results are shown 
in Table III. In each Example, the yield of saturated acids was only below 
2% and aldehydes were produced only in trace amounts. The conversion of 
butene-1 and 1,3-butadiene was 100% in Examples 18 through 28 and 95% in 
Example 17. 
Table III 
______________________________________ 
Metal (X)-containing 
Reac- Yield of 
compound and tion maleic 
Ex. amount used temp. anhydride 
No. X (g) (.degree. C.) 
(%) 
______________________________________ 
17 Na NaNO.sub.3 0.5 400 53.0 
18 Na NaNO.sub.3 0.5 425 55.8 
19 Na NaNO.sub.3 0.5 450 54.0 
20 Ca Ca(NO.sub.3).sub.2 . 4H.sub.2 O 
1.39 425 55.2 
21 Mg Mg(NO.sub.3).sub.2 . 6H.sub.2 O 
1.51 425 58.0 
22 Fe Fe(NO.sub.3).sub.2 . 6H.sub.2 O 
1.69 425 55.5 
23 Zr ZrO(NO.sub.3).sub.2 . 2H.sub.2 O 
1.57 400 55.0 
24 B H.sub.3 BO.sub.3 
0.36 425 55.9 
25 Mn Mn(NO.sub.3).sub.2 . 6H.sub.2 O 
1.69 425 56.1 
26 Ag AgNO.sub.3 1.00 425 55.1 
27 Mo (NH.sub.4).sub.6 Mo.sub.7 O.sub.24 . 4H.sub.2 O 
1.05 425 54.9 
28 Na NaNO.sub.3 0.5 425 68.0 
______________________________________ 
COMATIVE EXAMPLE 15 
Following the procedure set forth in Examples 17 through 28, a catalyst was 
prepared wherein the mixture of vanadium pentoxide and anatase-type 
titanium dioxide was calcined at 600.degree. C. instead of 700.degree. C. 
with all other conditions remaining substantially the same. The titanium 
dioxide present in the catalyst so prepared proved by X-ray 
diffractiometry to be of an anatase-type structure. 
Using the aforesaid catalyst, maleic anhydride was prepared from butene-1 
in a manner similar to that in Example 18. The conversion of butene-1 was 
100% and the yield of maleic anhydride was only 48%.