Process for producing methacrolein

Methacrolein is produced in a high yield by catalytically oxidizing isobutylene at a temperature of from 250.degree. to 500.degree. C. by using a catalyst represented by the formula: EQU Mo.sub.a Co.sub.b Fe.sub.c Bi.sub.d Cs.sub.e X.sub.f Y.sub.g O.sub.h wherein X is either both vanadium and palladium, Y is at least one member selected from titanium, nickel, tin and zirconium, a=12, b=2-12, c=0.5-7, d=0.1-5, e=0.0005-0.5, f=0.01-2, g=0-5 and h is a positive number proportional to the number of oxygen atoms satisfying the average valency of the metal atoms stated in the formula, which catalyst has a high resistance to compression and abrasion and exhibits a high catalytic efficiency, mechanical strength and durability.

FIELD OF THE INVENTION 
The present invention relates to a process for producing methacrolein by 
the catalytic oxidation of isobutylene in a vapor phase with molecular 
oxygen at an elevated temperature. More particularly, the present 
invention relates to a process for producing methacrolein by the catalytic 
oxidation of isobutylene in a vapor phase with molecular oxygen at an 
elevated temperature by using a new type of catalyst having a more 
enhanced catalytic activity, durability and mechanical strength than those 
of conventional catalysts containing molybdenum, bismuth, iron, cobalt and 
an alkali metal as catalytic ingredients. 
BACKGROUND OF THE INVENTION 
Known are various types of processes for producing unsaturated aliphatic 
aldehydes such as acrolein and methacrolein by the catalytic oxidation of 
olefins such as propylene and isobutylene in a vapor phase with molecular 
oxygen at an elevated temperature. Also, various types of catalysts 
effective for the above-mentioned processes are known. In connection with 
such known processes and catalysts, it is believed that, in general, the 
production of methacrolein from isobutylene is more technically difficult 
than that of acrolein from propylene. In fact, it is known that when 
acrolein and methacrolein are produced respectively from propylene and 
isobutylene by using the same type of catalyst which is believed to be 
effective for catalytically converting olefins into corresponding 
unsaturated aliphatic aldehydes, the yield of methacrolein is usually 
lower than that of acrolein. For example, Japanese Patent Application 
Publication No. 47-42813(1972) states that the yield of methacrolein is 5 
to 10% below that of acrolein. In this connection, it is presumed that the 
difference in yield between methacrolein and acrolein is derived from the 
fact that the methacrolein molecule has a branched carbon chain, that is, 
a methyl group, which is not contained in the acrolein molecule. 
Therefore, it is considered that, in order to convert isobutylene 
catalytically into methacrolein in a high yield, a new type of catalyst 
different from conventional catalysts effective for the catalytic 
oxidation of propylene into acrolein, should be provided. 
The conventional catalysts for catalytically converting isobutylene into 
methacrolein usually contain as catalytic ingredients, molybdenum, 
bismuth, iron, cobalt and an alkali metal such as potassium 
(Mo-Bi-Fe-Co-K). This type of conventional catalysts is disclosed, for 
example, in Japanese Patent Application Publication No. 47-42813(1972) 
(Co-Fe-Bi-W-Mo-Si-K-P-O), Japanese Patent Application Publication No. 
48-17253(1973) (Ni-Co-Fe-Bi-P-Cs-K-Mo-O), U.S. Pat. No. 3,966,823 
(Ni-Co-Fe-Bi-P-K-Mo-O), U.S. Pat. No. 4,049,577 (Co-Fe-Bi-Mo-K-O), 
U.S.Pat. No. 3,825,502 (Co-Fe-Bi-Mg-K-Mo-O), Japanese Patent Application 
Publication No. 51-47684(1976) (Co-Fe-Bi-Cr-K-Mo-O), Japanese Patent 
Application Laying-open No. 48-52713(1973) (Co-Fe-Bi-Cs-K-Mo-O) and 
Japanese Patent Application Laying-open No. 51-34107(1976) 
(Mn-K-Ni-Co-Fe-Bi-Mo-O). 
The above-mentioned types of conventional catalysts can enable methacrolein 
to be produced in a yield of approximately 70%. However, this level of 
yield is not high enough for industrial use. 
Also, it was discovered by the inventors of the present invention that the 
conventional catalysts have relatively poor resistances to attrition and 
compression and also exhibit a relatively poor durability in resistances 
to attrition and compression. Therefore, the conventional catalysts are 
often disintegrated during the catalytic oxidizing operation. The 
disintegration of catalysts results in a reduction in the catalytic 
efficiency of the catalysts. 
Under these circumstances, it is desired to provide a new type of catalyst 
which enables methacrolein to be produced in a high yield and which 
exhibits an enhanced mechanical strength and durability. 
As a result of a study on the improvement of the catalyst, it was 
discovered by the inventors of the present invention that the catalytic 
efficiency and the mechanical strength and durability of the catalyst can 
be enhanced by using cesium as an alkali metal catalytic ingredient and by 
adding an additional catalytic ingredient consisting of at least one 
member selected from the group of vanadium and palladium, to the 
conventional catalytic ingredient, that is, molybdenum, bismuth, iron, 
cobalt and an alkali metal. 
Furthermore, it was discovered by the inventors that the catalytic 
efficiency and the mechanical strength and durability of the 
above-mentioned catalyst can be further improved by adding an additional 
catalytic ingredient consisting of at least one member selected from 
titanium, nickel, tin and zirconium to the above-mentioned conventional 
additional catalytic ingredients. 
The present invention is based on the above-mentioned discoveries. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a process for producing 
methacrolein by the catalytic oxidation of isobutylene in a vapor phase 
with molecular oxygen at an elevated temperature in the presence of a 
catalyst which is capable of enhancing the yield of methacrolein and which 
has an enhanced mechanical strength and durability. 
The above-mentioned object can be attained by the process of the present 
invention which comprises bringing a feed gas containing isobutylene and 
molecular oxygen into contact with a catalyst at a temperature of from 
250.degree. to 500.degree. C., which process is characterized in that the 
catalyst is represented by the formula (1): 
EQU Mo.sub.a Co.sub.b Fe.sub.c Bi.sub.d Cs.sub.e X.sub.f Y.sub.g O.sub.h ( 1) 
wherein Mo represents a molybdenum atom, Co represents a cobalt atom, Fe 
represents an iron atom, Bi represents a bismuth atom, Cs represents a 
cesium atom, X represents at least one member selected from the group 
consisting of vanadium and palladium atoms, Y represents at least one 
member selected from the group consisting of titanium, nickel, tin and 
zirconium atoms, O represents an oxygen atom, the subscripts a through g 
respectively represent a positive number proportional to the number of 
respective metal atoms, wherein when a is 12, b through g fall 
respectively within the following ranges: b=2 to 12, c=0.5 to 7, d=0.1 to 
5, e=0.0005 to 0.5, f=0.01 to 2 and g=0 to 5, and the subscript h 
represents a positive number proportional to the number of oxygen atoms 
satisfying the average valence of the above-mentioned metal atoms. It is 
preferable that the values of the subscripts b through g be respectively 
in the ranges of: b=4 to 10, c=1 to 5, d=0.5 to 4, e=0.01 to 0.3, f=0.05 
to 1.5 and g=0.1 to 5. 
DETAILED DESCRIPTION OF THE INVENTION 
In the catalyst usable for the process of the present invention, it is 
important that cesium is used as an alkali metal catalytic ingredient, 
either or both of vanadium and palladium are added, as an additional 
catalytic ingredient, to the conventional catalytic ingredient, that is, 
molybdenum, bismuth, iron, cobalt and an alkali metal, and optionally, 
that a further additional catalytic ingredient consisting of one, two, or 
more members from the group consisting of titanium, nickel, tin and 
zirconium is added to the above-mentioned conventional and additional 
catalytic ingredients. If an alkali metal such as potassium, sodium, 
rubidium and lithium, which are different from cesium, is used, the 
resultant catalyst will cause methacrolein to be produced with a poor 
percent selectivity (which term will be defined hereinafter) and with a 
relatively low yield of 70% or less. Accordingly, the alkali metals which 
are different from cesium cannot be used to attain the object of the 
present invention. Evenif cesium is used as an alkali metal catalytic 
ingredient, if the additional catalytic ingredient consisting of at least 
one member selected from vanadium and palladium is not used, the resultant 
catalyst will cause methacrolein to be produced with a poor percent 
conversion of isobutylene (which term will be defined hereinafter), and 
also with a relatively low yield. Also, even if the additional catalytic 
ingredient is used, if cesium is not used as an alkali metal catalytic 
ingredient, the use of the resultant catalyst will result in a poor 
percent selectivity to methacrolein and in a relatively low yield of 
methacrolein. 
In the conventional catalysts, it was believed that either the element 
phosphorus or arsenic is effective as an additional catalytic ingredient 
for enhancing the catalytic efficiency of the catalyst. However, 
surprisingly, in spite of the fact that neither the element phosphorus or 
arsenic is used, the use of a combination of cesium with the additional 
catalytic ingredient results not only in a high percent selectivity to 
methacrolein and a high yield of methacrolein, but also in a high 
mechanical strength, for example, resistance to attrition and crush 
strength, and durability of the resultant catalyst. 
The addition of the further additional catalytic ingredient, consisting of 
at least one member selected from the group comprising titanium, nickel, 
tin and zirconium, is effective not only for enhancing the mechanical 
strength and durability of the resultant catalyst but also for increasing 
the yield of methacrolein. 
The values of the subscripts a through h should be in the range as 
specified hereinbefore. If any value of a through h falls outside of the 
specified range, the resultant catalyst will cause the percent conversion 
of isobutylene and/or the percent selectivity to methacrolein to be poor. 
In the process of the present invention, the use of the novel catalyst (as 
defined hereinafter) enhances both the percent conversion of isobutylene 
and the percent selectivity to methacrolein. Therefore, the yield of the 
resultant methacrolein can be increased by using the novel catalyst. Also, 
since the special catalyst usable for the present invention has an 
enhanced mechanical strength and durability, the process of the present 
invention can be uniformly carried out over a long period of time without 
disintegration of the catalyst and change in the catalytic efficiency of 
the catalyst. Accordingly, it is obvious that the process of the present 
invention can be very advantageous for continuously producing methacrolein 
on an industrial scale. 
In the catalyst usable for the present invention, the respective metal 
ingredients are present in the form of metal oxides which include those of 
the type in which each single metal is bonded with oxygen, those of the 
type in which two or more metals are bonded with oxygen to form a complex 
and those of the type in which the above-mentioned two types of oxides are 
combined together. 
The catalyst of the above formula (1), usable for the process of the 
present invention, may be prepared in any conventional manner by using, as 
the starting raw material, oxides, salts and other compounds, containing 
the above-mentioned metal ingredients. However, calcination of the 
catalyst, i.e., the final step of the catalyst preparation, should 
preferably be carried out at a temperature in the range of from 
550.degree. to 800.degree. C., more preferably, from 580.degree. to 
750.degree. C., and over a period of 1 to 20 hours, more preferably, from 
2 to 10 hours, for obtaining the desired yield of methacrolein and 
catalyst strength. This temperature range is higher than the range of from 
400.degree. to 500.degree. C. popularly employed for preparing the 
conventional catalysts based on molybdenum, bismuth, iron and cobalt. 
A calcining temperature falling outside of the above-mentioned range may 
sometimes cause a decrease in the mechanical strength of the resultant 
catalyst and/or the yield of methacrolein. The calcining operation is 
carried out in a gas containing oxygen, usually an air atmosphere. 
The general procedures for preparing a catalyst are as follows. Oxides, 
salts and other compounds containing the above-mentioned metal ingredients 
are mixed together in an aqueous medium to prepare a uniform slurry. The 
aqueous slurry is dried at a temperature not exceeding 300.degree. C. In 
this case, the drying operation is preferably carried out in two steps. 
That is, in the first step, the aqueous dispersion is heated at a 
temperature of from 100.degree. to 150.degree. C., preferably at 
approximately 120.degree. C., to evaporate water; and in the second step, 
the dried product is heated at a temperature of from 150.degree. to 
300.degree. C. preferably at approximately 200.degree. C., for a period of 
3 to 20 hours to eliminate volatile substances, for example, ammonium 
nitrate and nitrogen oxides. The dried product is shaped into pellets or 
particles of a desired shape and size. The shaped pellets or particles are 
calcined under the above-mentioned conditions. 
As examples of the starting raw materials which can be used in the 
preparation of the catalyst are, for example, molybdenum compounds such as 
molybdic acid, ammonium molybdate and molybdenum trioxide; cobalt 
compounds such as cobalt carbonate, cobalt nitrate, cobaltous oxide, 
tricobalt tetroxide, cobalt chloride, cobaltous hydroxide, cobaltic 
hydroxide and cobalt sulfide; iron compounds such as ferrous nitrate, 
ferric nitrate, ferrous oxide, ferric oxide, ferrous carbonate, ferrous 
sulfide, ferrous chloride, ferric chloride, ferrous hydroxide, ferric 
hydroxide, ferrous sulfate, ferric sulfate, ammonium ferrous sulfate and 
ammonium ferric sulfate; bismuth compounds such as bismuth nitrate, 
bismuth dichloride, bismuth trichloride, bismuth pentoxide, bismuth 
trioxide, bismuth tetroxide, bismuth oxynitrate, bismuth hydroxide, 
bismuth subnitrate and bismuth oxychloride; cesium compounds such as 
cesium nitrate, cesium chloride, cesium hydroxide, cesium carbonate and 
cesium oxide; vanadium compounds such as vanadium chloride, ammonium 
metavanadate, vanadyl chloride, vanadyl sulfate and vanadium pentoxide; 
palladium compounds such as palladium nitrate, palladium hydroxide, 
palladium chloride and palladium oxide; titanium compounds such as 
titanium dioxide, titanic acid, titanium trichloride and titanium 
tetrachloride; nickel compounds such as nickel carbonates, nickel nitrate, 
nickel oxide, dinickel trioxide, nickel chloride, nickel hydroxide and 
nickel sulfate; tin compounds such as stannic oxide, tin hydroxide, 
stannic chloride, stannous oxide and stannic acid; and zirconium compounds 
such as zirconium oxide, zirconium oxynitrate and zirconium hydroxide. 
Among the above-mentioned compounds, the compounds which are most 
preferable as starting raw materials are nitrates and ammonium salts of 
the respective ingredient metals. 
The procedures for preparing a catalyst usable for the present invention 
will be described in more detail with reference to a catalyst consisting 
of molybdenum, bismuth, iron, cobalt, cesium, vanadium and oxygen. 
Predetermined amounts of ammonium molybdate and ammonium metavanadate are 
dissolved in water, preferably warm water, to prepare an aqueous solution. 
Added by drops to this aqueous solution, while the solution is being 
stirred, are an acidic solution of a predetermined amount of bismuth 
nitrate in nitric acid and an aqueous solution of predetermined amounts of 
ferric nitrate, cobalt nitrate and cesium nitrate. The so-obtained aqueous 
slurry is then heated at a temperature of from 100.degree. to 150.degree. 
C., preferably at approximately 120.degree. C., by using a drum dryer or a 
spray dryer to evaporate water from the slurry. Next, the slurry is again 
heated at a temperature of from 150.degree. to 300.degree. C., preferably 
at approximately 200.degree. C., until no more ammonium nitrate and 
nitrogen oxides are evolved from the dried product and the slurry is 
completely dried. The resultant dried product is shaped or granulated into 
a desired shape and size of pellets or particles. If necessary, the 
particles can be separated by using a screen having a desired mesh to 
collect particles having a particular desired size. The particles are 
finally calcined, preferably at a temperature of from 550.degree. to 
800.degree. C., more preferably, from 580.degree. to 750.degree. C. 
In the case where palladium is used in place of vanadium as a catalytic 
metal ingredient, it is preferable to use palladium nitrate as a starting 
raw material. A predetermined amount of palladium nitrate is dissolved 
together with ferric nitrate, cobalt nitrate and cesium nitrate in warm 
water. The solution is added dropwise into a solution of ammonium 
molybdate alone in warm water while the resultant mixture is being 
stirred. 
In the case where titanium is added as a catalytic metal ingredient, it is 
preferable that titanium dioxide be suspended in an aqueous solution of 
ammonium molybdate alone or together with ammonium metavanadate. Also, in 
the case where the catalyst contains a further additional catalytic 
ingredient, it is preferable to carry out the calcining operation at a 
temperature of from 550.degree. to 800.degree. C., more preferably, from 
580.degree. to 750.degree. C., in order to increase the reproducibility in 
the catalytic activity and the durability of the catalyst. 
The catalyst may be used alone or in combination with a carrier. Carriers 
such as those known for supporting conventional oxidation catalysts and 
for bringing about favorable effects to the reaction involved, e.g., 
silica, alumina, silica-alumina, titania, diatomaceous earth and 
carborundum, may be used. These carriers may be combined with the catalyst 
either during or after preparation of the catalyst. 
In general, the size and shape of the catalyst particle used, and the use 
of a carrier are not critical factors because they do not greatly affect 
the resultant catalytic activity. 
In carrying out the process of the present invention, it is not necessary 
to use a highly purified isobutylene. Thus, the isobutylene may contain 
other hydrocarbons, for example, n-butane and n-butene. That is, the 
source of isobutylene may be a C.sub.4 fraction which is produced from 
naphtha cracking and which contains, as main components, isobutylene 
n-butene, 1,3-butadiene and n-butane. Another source of isobutylene may be 
a hydrocarbon mixture which is a residue obtained by extracting 
1,3-butadiene from the C.sub.4 fraction. This hydrocarbon mixture contains 
isobutylene and n-butene predominantly. When this type of hydrocarbon 
mixture is used as a source of isobutylene for the process of the present 
invention, not only isobutylene is converted into methacrolein but 
n-butene is also converted into 1,3-butadiene. That is, in this case, 
methacrolein and 1,3-butadiene, which are both useful for industrial uses, 
are simultaneously produced, thus constituting an advantage from an 
economic view point. The hydrocarbon mixture may contain isobutane, 
n-butane and propane, in addition to isobutylene and n-butene. In this 
case, it is preferable for the sum of the molar amounts of isobutylene and 
n-butene to correspond to 50% or more, more preferably, to 70% or more, 
with respect to the total molar amount of the hydrocarbon mixture. 
In carrying out the process of the present invention, an inert gas which is 
not reactive to catalytic oxidation may be used as a diluent gas for the 
feed gas. The diluent gas may be steam, nitrogen gas, carbon dioxide gas, 
n-butane gas, isobutane gas or propane gas. 
Likewise, the molecular oxygen used also needs not be highly purified. That 
is, oxygen-containing gases, such as air or a mixture of pure molecular 
oxygen and the above-mentioned diluent gas, may be conveniently used. Air 
particularly, may be advantageously used. The relative proportion of 
molecular oxygen in the feed gas is usually in the range of from 0.4 to 5 
moles, more preferably, from 0.5 to 3 moles, per mole of isobutylene. 
The catalytic oxidation of the present invention is carried out at a 
temperature in the range of from 250.degree. to 500.degree. C., preferably 
from 300.degree. to 480.degree. C. The contact time is usually in the 
range of from 0.2 to 20 seconds, preferably from 0.5 to 15 seconds. 
The reaction may be carried out under atmospheric pressure although 
superatmospheric or subatmospheric pressure may be used if desired. 
The catalytic oxidation reaction may be carried out in a fixed bed, a 
moving bed or a fluidized bed. When a fluidized bed is employed, it is 
preferable to use a catalyst having a particle size in the range of from 
30 to 100 microns. 
If it is necessary, the resultant methacrolein can be isolated from the 
reaction mixture by using any kind of conventional isolating processes, 
for example, by the absorption of methacrolein by cold water followed by 
the stripping and distillation of methacrolein. 
The present invention will be further clarified by the Examples and 
Comparison Examples set forth below. In all of the examples, "%" is 
expressed by weight unless otherwise specified. In these examples, the 
selective conversion of isobutylene to methacrolein and yield of 
methacrolein were calculated in accordance with the following equations. 
##EQU1## 
The moles of isobutylene fed, the moles of isobutylene consumed and the 
moles of methacrolein produced were determined after one hour had elapsed 
from the start of the reaction. 
The crush strength of the catalyst was determined as follows. 
A catalyst tablet (5 mm in diameter and 5 mm in height) was placed on a 
testing plate and compressed by using a Kiya-type hardness tester until 
the tablet was crushed. The value of the compressive load in Kg under 
which the tablet was crushed was measured. The above-mentioned testing 
procedures were repeated 50 times. The crush strength of the catalyst 
tablet was represented by an average value calculated from the results of 
50 tests. 
The resistance of the catalyst to attrition was determined as follows. 
A glass test tube having an inner diameter of 2.54 cm and a height of 300 
cm was used. 50 tablets of a catalyst were dropped down from the top of 
the glass test tube to the bottom thereof. The total weight of the tablets 
which were crushed into particules having 6 mesh size or less was 
measured. The resistance of the catalyst to attrition was thereafter 
represented by a ratio (%) of the weight of the crushed tablets to the 
weight of the original 50 tablets.

EXAMPLE 1 
141.3 g of ammonium molybdate [(NH.sub.4).sub.6 Mo.sub.7 O.sub.24 1. 
4H.sub.2 O] and 0.78 g of ammonium metavanadate [NH.sub.4 VO.sub.3 ]were 
dissolved in 200 ml of water maintained at a temperature of 40.degree. C. 
A solution of 38.8 g of bismuth nitrate [Bi(NO.sub.3).sub.3. 5H.sub.2 O] 
in 50 ml of a 15% nitric acid aqueous solution was mixed into a solution 
of 64.6 g of ferric nitrate [Fe(NO.sub.3).sub.3. 9H.sub.2 O], 0.078 g of 
cesium nitrate [CsNO.sub.3 ] and 186.2 g of cobalt nitrate 
[Co(NO.sub.3).sub.2. 6H.sub.2 O] in 200 ml of water of a temperature 
adjusted to 40.degree. C. The mixture was admixed dropwise into the 
above-prepared aqueous solution of ammonium molybdate and ammonium 
metavanadate while the admixed solution was being stirred. 
The admixed solution was first dried at a temperature of 120.degree. C. by 
using a drum dryer. The initially dried material was additionally dried at 
a temperature of 200.degree. C. for 10 hours by using an oven. The 
resultant material was shaped into tablets having a diameter of 5 mm and a 
height of 5 mm by means of a tablet-forming machine. The tablets were 
calcined at a temperature of 650.degree. C. for 5 hours in an air 
atmosphere to provide a catalyst. In the catalyst thus prepared, the 
atomic ratio of Mo:Bi:Co:Fe:Cs:V was 12:1:8:2:0.005:0.1. 
10 ml of the catalyst tablets were charged into a U-shaped glass tube 
having an inner diameter of 8 mm. A feed gas containing isobutylene, air 
and steam in a molar ratio of 1:10:6 was passed through the U-shaped tube 
at a temperature of 390.degree. C. at a flow rate of 180 ml/min so that 
the contact time of the feed gas with the catalyst tablets was 3.3 
seconds. The percent conversion of isobutylene, the percent selectivity to 
methacrolein and the yield of methacrolein were determined. The results of 
Example 1 are shown in Table 1. 
EXAMPLES 2 THROUGH 6 
In each of Examples 2 through 6, the same procedures as those described in 
Example 1 were carried out, except that the atomic ratio of 
Mo:Bi:C0:Fe:Cs:V was varied for each of the Examples 2 through 6 in 
accordance with the ratios shown in Table 1. In example 3, the catalytic 
oxidation was carried out at a temperature of 380.degree. C. The results 
of Examples 2 through 6 are shown in Table 1. 
EXAMPLES 7 AND 8 
In each of Examples 7 and 8, procedures identical to those described in 
Example 1 were carried out, except that 1.84 g of palladium nitrate 
[Pd(NO.sub.3).sub.2 ] were added to the mixed solution. The atomic ratio 
of Mo:Bi:Co:Fe:Cs:V:Pd for each of Examples 7 and 8 is respectively shown 
in Table 1. Also, in Example 7, the catalytic oxidation was carried out at 
a temperature of 380.degree. C. The results of Examples 7 and 8 are shown 
in Table 1. 
EXAMPLES 9 AND 10 
In each of Examples 9 and 10, the same procedures as those used in Example 
8 were carried out, except that no ammonium metavanadate was used. The 
atomic ratio of Mo:Bi:Co:Fe:Cs:Pd for each of the two examples is 
respectively shown in Table 1. In Example 9, the catalytic contacting 
temperature was 360.degree. C. The results of Examples 9 and 10 are shown 
in Table 1. 
Table 1 
__________________________________________________________________________ 
Catalytic Selectivity 
Composition of Catalyst 
contacting 
Conversion 
to Yield of 
Example 
(Atomic ratio) temperature 
of isobutylene 
methacrolein 
methacrolein 
No. Mo Co 
Fe 
Bi 
Cs V Pd 
(.degree.C.) 
(%) (%) (%) 
__________________________________________________________________________ 
1 12 8 2 1 0.005 
0.1 
-- 
390 96.5 87.2 84.1 
2 10 8 2 1 0.05 
0.1 
-- 
390 95.3 86.4 82.3 
3 10 8 2 1 0.1 
0.5 
-- 
380 94.9 86.0 81.6 
4 12 7 4 1 0.01 
0.1 
-- 
390 94.8 86.9 82.4 
5 12 8 3 2 0.01 
0.1 
-- 
390 98.9 84.7 83.8 
6 11 6 4 1 0.01 
0.1 
-- 
390 96.9 85.9 83.2 
7 10 8 2 1 0.05 
0.1 
0.1 
380 98.3 84.5 83.1 
8 11 8 3 1 0.01 
0.1 
0.1 
390 97.3 85.0 82.7 
9 10 8 2 1 0.005 
-- 
0.1 
360 97.8 84.3 82.4 
10 10 8 2 1 0.1 
-- 
0.5 
390 96.8 85.7 83.0 
__________________________________________________________________________ 
(Contact time: 3.3 seconds) 
COMISON EXAMPLE 1 
The same procedures as those described in Example 1 were carried out, 
except that neither cesium nitrate nor ammonium metavanadate were used, 
the atomic ratio of the metal ingredients was the same as that shown in 
Table 2 and the catalytic contacting temperature was 370.degree.C. The 
results of Comparative Example 1 are shown in Table 2. 
COMISON EXAMPLES 2 AND 3 
In each of Examples 2 and 3, the same procedures as those described in 
Example 1 were carried out, except that no ammonium metavanadate was used 
and the atomic ratio of the metal ingredients in the catalyst for each of 
the two comparison Examples was the same as that respectively shown in 
Table 2. The results of Comparison Examples 2 and 3 are shown in Table 2. 
COMISON EXAMPLES 4 THROUGH 7 
In each of Examples 4 through 7, the same procedures as those described in 
Example 1 were carried out, except that no ammonium metavanadate was used, 
cesium nitrate which served as the raw material for the alkali metal 
catalytic ingredient was replaced respectively by sodium nitrate in 
Comparison Example 4, by rubidium nitrate in Comparison Example 5 and by 
potassium nitrate in Comparison Examples 6 and 7 in accordance with the 
amounts respectively shown in Table 2, and the atomic ratio of the metal 
ingredients in the resultant catalyst for each of these Comparison 
Examples was the same as that respectively shown in Table 2. In Comparison 
Examples 4 and 7, catalytic oxidation was carried out at a temperature of 
370.degree. C. The results of Comparison Examples 4 through 7 are shown in 
Table 2. 
COMISON EXAMPLE 8 
The same procedures as those described in Example 1 were carried out, 
except that no cesium nitrate was used, the atomic ratio of the metal 
ingredients in the resultant catalyst was the same as that shown for this 
Comparison Example in Table 2, and catalytic oxidation was carried out at 
a temperature for a contact time as specified in Table 2 for this 
Comparison Example. The results of Comparison Example 8 are shown in Table 
2. 
COMISON EXAMPLE 9 
A comparison catalyst having an atomic ratio of the catalytic metal 
ingredients as shown in Table 2 was prepared by following procedures 
similar to those used in Example 9, except that no cesium nitrate was 
used. The same reaction procedures as those described in Example 1 were 
carried out, except that the contacting temperature and the contact time 
followed were those shown in Table 2 for this Comparison Example 9. The 
results of Comparison Example 9 are shown in Table 2. 
COMISON EXAMPLES 10 THROUGH 12 
In each of Comparison Examples 10 through 12, a comparison catalyst was 
prepared by following the same procedures as those described in Example 1, 
except that cesium nitrate which served as a raw material of alkali metal 
catalytic ingredient was replaced respectively by potassium nitrate in 
Comparison Example 10, by sodium nitrate in Comparison Example 11 and by 
rubidium nitrate in Comparison Example 12. Also, a catalytic conversion of 
isobutylene was carried out by carrying out the same procedures as those 
described in Example 1, except that the above-prepared comparison catalyst 
was used, and the contacting temperature and the contact time followed 
were those respectively specified in Table 2 for Comparison Examples 10 
through 12. 
The comparison catalysts of Comparison Examples 11 and 12 were prepared by 
calcining at temperatures of 660.degree. C. and 620.degree. C., 
respectively. 
The results of both Comparison Examples are shown in Table 2. 
Table 2 
__________________________________________________________________________ 
Catalytic 
contacting 
Conversion 
Selectivity 
Comparison 
Composition of catalyst 
Contact 
temper- 
of to Yield of 
Example 
(Atomic ratio) time ature isobutylene 
methacrolein 
methacrolein 
No. Mo Co 
Fe 
Bi 
Alkali metal 
V Pd 
(sec) 
(.degree.C.) 
(%) (%) (%) 
__________________________________________________________________________ 
1 10 8 2 1 -- -- 
-- 
3.3 370 96.2 50.5 48.5 
2 10 8 2 1 Cs = 0.03 
-- 
-- 
3.3 390 74.9 84.3 63.1 
3 10 8 2 1 Cs = 0.1 
-- 
-- 
3.3 390 25.2 87.0 21.9 
4 10 8 3 1 Na = 0.5 
-- 
-- 
3.3 370 97.3 68.2 66.4 
5 10 8 3 1 Rb = 0.05 
-- 
-- 
3.3 390 94.1 70.5 66.3 
6 10 8 2 1 K = 0.01 
-- 
-- 
3.3 370 96.8 69.3 67.1 
7 10 8 2 1 K = 0.3 
-- 
-- 
3.3 390 91.0 72.3 65.8 
8 10 8 2 1 -- 0.1 
-- 
3.0 360 98.3 64.1 63.0 
9 10 8 2 1 -- -- 
0.1 
3.0 340 95.0 58.2 55.3 
10 10 8 2 1 K = 0.05 
0.1 
-- 
3.0 370 97.6 68.2 66.6 
11 10 8 2 1 Na = 0.1 
0.1 
-- 
3.0 370 95.2 65.4 62.3 
12 10 8 2 1 Rb = 0.1 
0.1 
-- 
3.0 390 89.3 75.1 67.1 
__________________________________________________________________________ 
COMISON EXAMPLES 13 THROUGH 17 
In each of Comparison Examples 13 through 17, a comparison catalyst was 
prepared by following the same procedures as those described in Example 1, 
except that the amounts of the raw materials of respective catalytic metal 
ingredients used were changed so that the resultant comparison catalysts 
had a catalytic metal ingredient composition, as shown in Table 3, which 
is outside of the scope of the present invention. 
In addition, the calcining temperature was adjusted to 600.degree. C. in 
Comparison Examples 13 and 14, to 650.degree. C. in Comparison Example 15, 
to 570.degree. C. in Comparison Example 16 and to 660.degree. C. in 
Comparison Example 17. 
By using the comparison catalysts, the same procedures for converting 
isobutylene as those described in Example 1 were carried out, except that 
the contacting temperature and the contact time were changed to those 
shown respectively in Table 3 for Comparison Examples 13 through 17. 
The results are shown in Table 3. 
COMISON EXAMPLE 18 
A comparison catalyst was prepared in accordance with the same procedures 
as those used in Example 9, except that the cesium nitrate as a raw 
material of an alkali metal catalytic ingredient was replaced by potassium 
nitrate and the resultant catalyst had the composition described in Table 
3. Next, the same procedures for catalytically converting isobutylene as 
those described in Example 1 were carried out, except that the contacting 
temperature and the contact time were changed to those shown in Table 3 
for Comparison Example 18. 
The results for this Comparison Example are shown in Table 3. 
COMISON EXAMPLE 19 
A comparison catalyst was prepared by following the same procedures as 
those used in Example 9, except that the amount of palladium nitrate 
employed was changed to a value which caused the composition of the 
resultant catalyst to be changed to that shown in Table 3 for Comparison 
Example 19, and the calcining temperature of 650.degree. C. was changed to 
670.degree. C. The resultant catalyst was used for carrying out the same 
procedures as those mentioned in Example 1 for catalytically converting 
isobutylene, except that the contacting temperature and the contact time 
were changed to those shown in Table 3 for Comparative Example 19. 
The results for this Comparative Example are shown in Table 3. 
From a comparison of the results of Examples 1 through 10 shown in Table 1 
with those of Comparison Examples 1 through 19 shown in Tables 2 and 3, it 
is clear that the process of the present invention produced a high percent 
yield of methacrolein, because the percent conversion of isobutylene and 
the percent selectivity to methacrolein of this process were both at a 
high level. On the contrary, the processes of Comparison Examples 1 
through 19 produced a relatively low percent yield of methacrolein, 
because either or both of the percent conversion of isobutylene and 
percent selectivity to methacrolein of these processes were at a low 
level. 
Table 3 
__________________________________________________________________________ 
Catalytic 
contacting 
Conversion 
Selectivity 
Comparison 
Composition of catalyst 
Contact 
temper- 
of to Yield of 
Example 
(Atomic ratio) time ature isobutylene 
methacrolein 
methacrolein 
No. Mo Co 
Fe 
Bi Alkali metal 
V Pd 
(sec) 
(.degree.C.) 
(%) (%) (%) 
__________________________________________________________________________ 
13 12 1 6 1 Cs = 0.01 
0.1 
-- 
3.3 390 93.7 69.3 64.9 
14 13 8 0.5 
1 Cs = 0.01 
0.1 
-- 
3.3 390 95.4 67.8 64.7 
15 12 8 3 0.05 
Cs = 0.01 
0.1 
-- 
3.0 390 90.4 73.8 66.7 
16 11 8 2 1 Cs = 0.75 
0.1 
-- 
3.3 410 32.9 86.4 28.4 
17 12 8 3 1 Cs = 0.01 
3 -- 
3.0 370 98.1 55.7 54.6 
18 10 8 2 1 K = 0.05 
-- 
0.1 
3.0 370 99.3 60.4 60.0 
19 12 8 3 1 Cs = 0.01 
-- 
3 3.0 360 97.3 52.1 50.7 
__________________________________________________________________________ 
EXAMPLE 11 
The same procedures for catalytically converting isobutylene into 
methacrolein as those described in Example 1 were continuously carried out 
for 100 hours by using the same catalyst (Mo.sub.12 Co.sub.8 Fe.sub.2 
Bi.sub.1 Cs.sub.0.005 V.sub.0.1) as that mentioned in Example 1. 
After 100 hours had elapsed from the start of the reaction, the percent 
conversion of isobutylene was 93.8%, the percent selectivity to 
methacrolein was 87.5% and the percent yield of methacrolein was 82.1%. 
That is, the yield of methacrolein was maintained at a substantially 
constant level during the entire reaction. 
The crush strength the catalyst tablets was 5.1 Kg 1 hour after the start 
of the reaction and 5.1 Kg 100 hours after the start of the reaction. That 
is, it was confirmed that the crush strength of the catalyst tablets did 
not change at all even though the tablets were continuously used for a 
long period of time. 
EXAMPLE 12 
By using the same catalyst (Mo.sub.10 Co.sub.8 Fe.sub.2 Bi.sub.1 Cs.sub.0.1 
Pd.sub.0.5) as that mentioned in Example 10, the same contacting 
procedures as those described in Example 1 were continuously carried out 
for 100 hours. After 100 hours had elapsed from the start of carrying out 
the contacting procedures, the percent conversion of isobutylene, the 
percent selectivity to methacrolein and the percent yield of methacrolein 
were respectively 96.5%, 85.8% and 82.8% which were similar to those 
observed 1 hour after the start of carrying out the contacting procedures. 
It was also confirmed that the crush strength of the catalyst tablets could 
be maintained constant during the contacting process. That is, 100 hours 
after the start of the process, the crush strength was observed to be 5.3 
Kg, the same crush strength as that observed after 1 hour from the start 
of the process. 
EXAMPLE 13 
The same procedures as those described in Example 1 were carried out and 
the catalyst tablets (Mo.sub.12 Bi.sub.1 Co.sub.8 Fe.sub.2 Cs.sub.0.005 
V.sub.0.1) were accordingly charged into a U-shaped reaction tube. A feed 
gas, containing 10 parts by volume of a hydrocarbon mixture gas, 100 parts 
by volume of air and 60 parts by volume of steam, was passed through the 
reaction tube at a flow rate of 170 ml/min under such a condition that the 
contact of the feed gas with the catalyst was maintained for 3.3 seconds 
at a temperature of 390.degree. C. 
A hydrocarbon gas mixture was a residual gas of the process in which 
1,3-butadiene was extracted from a C.sub.4 fraction produced during the 
process of naphtha cracking. This hydrocarbon gas mixture had a 
composition as that shown in Table 4 for example 13. 
Table 4 
______________________________________ 
Compound Molar percent 
______________________________________ 
Propane 0.1 
Propylene 0.5 
Isobutane 1.5 
n-Butane 8.1 
n-Butene 41.9 
Isobutylene 47.0 
1,3-Butadiene 0.4 
Propadiene 0.5 
______________________________________ 
The results of Example 13 are shown in Table 5. 
Table 5 
______________________________________ 
Item Percent 
______________________________________ 
Conversion of isobutylene 
97.2 
Selectivity to methacrolein 
84.2 
Yield of Methacrolein 
81.6 
Conversion of n-butene.sup.(*) 
Selectivity to 1,3-butadiene.sup.(**) 
75.4 
______________________________________ 
Note:- 
.sup.(*) Percent conversion of 
nbutene- 
##STR1## 
.sup.(**) Percent selectivity to 1,3butadiene 
##STR2## 
EXAMPLE 14 
In 200 ml of warm water maintained at a temperature of 40.degree. C., 141.3 
g of ammonium molybdate [(NH.sub.4).sub.6 Mo.sub.7 O.sub.24. 4H.sub.2 O] 
and 0.78 g of ammonium metavanadate [NH.sub.4 VO.sub.3 ] were dissolved 
and 6.39 g of titanium dioxide were suspended. A mixture of a solution of 
38.8 g of bismuth nitrate [Bi(No.sub.3).sub.3. 5H.sub.2 O] in 50 ml of a 
15% nitric acid aqueous solution and a solution of 64.6 g of ferric 
nitrate [Fe(NO.sub.3).sub.3. 9H.sub.2 O], 0.078 g of cesium nitrate 
[CsNO.sub.3 ] and 186.2 g of cobalt nitrate [Co(NO.sub.3).sub.2. 6H.sub.2 
O] in 200 ml of warm water maintained at a temperature of 40.degree. C., 
was admixed dropwise into the thus-prepared aqueous solution suspension 
while the admixed solution was being stirred. 
The admixed aqueous slurry was initially dried at a temperature of 
120.degree. C. by using a drum dryer, and then the first dried product was 
dried for a second time at a temperature of 200.degree. C. for 10 hours by 
using an oven. The second dried product was shaped into tablets each 
having a diameter of 5 mm and a height of 5 mm by using a tablet-forming 
machine. The resultant tablets were calcined in an air atmosphere at a 
temperature of 650.degree. C. for 5 hours. The resultant catalyst had an 
atomic ratio of Mo:Bi:Co:Fe:Cs:V:Ti=12:1:8:2:0.005:0.1:1. The measured 
crush strength and resistance to attrition of the catalyst tablets are 
shown in Table 6. 10 ml of the catalyst tablets were placed in a U-shaped 
glass reaction tube having an inner diameter of 8 mm. A feed gas 
consisting of isobutylene, air and steam in a molar ratio of 1:10:6 was 
passed through the reaction tube at a flow rate of 200 ml/min under such a 
condition that the contact of the feed gas with the catalyst was 
maintained for 3.0 seconds at a temperature of 390.degree. C. 
The results of Example 14 are shown in Table 6. 
EXAMPLES 15 THROUGH 19 
The same procedures as those described in Example 14 were carried out, 
except that the titanium dioxide was replaced by zirconium oxide in 
Example 15, by stannic oxide in Example 16, by nickel oxide in Example 17, 
by a mixture of zirconium oxide and stannic oxide in Example 18 and by a 
mixture of titanium dioxide and stannic oxide in Example 19 respectively 
in the amounts shown in Table 6, and that, in only Example 16, the 
conversion of isobutylene was carried out at a temperature of 370.degree. 
C. The obtained catalysts had the compositional make-ups, crush strength 
the resistance to attrition as shown in Table 6. 
The results of the conversion of isobutylene in the respective Examples 15 
through 18 are shown in Table 6. 
EXAMPLE 20 
Procedures identical to those described in Example 14 were carried out, 
except that no ammonium metavanadate was used and palladium nitrate was 
contained in the aqueous solution of ferric nitrate, cesium nitrate and 
cobalt nitrate. The resultant catalyst tablets has the compositional 
make-ups crush strength and the resistance to attrition as shown in Table 
6. 
Also, the results of the catalytic conversion of isobutylene are shown in 
Table 6. 
EXAMPLES 21, 22 AND 23 
Procedures identical to those used in Example 20 were conducted, except 
that the titanium dioxide employed in Example 20 was replaced by zirconium 
oxide in Example 21, by stannic oxide in Example 22, and by nickel oxide 
in Example 23 and that the resultant catalyst had the compositional 
make-ups, crush strength and resistance to attrition as shown in Table 6. 
Also, the results of the catalytic conversion of isobutylene are shown in 
Table 6. 
EXAMPLES 24 AND 25 
Procedures identical to those described in Example 14 were carried out, 
except that in both Examples 24 and 25, palladium nitrate was added to the 
aqueous solution of ferric nitrate, cesium nitrate and cobalt nitrate and 
the conversion of isobutylene was conducted at a temperature of 
370.degree. C. In Example 25, the titanium dioxide was replaced by stannic 
oxide. The catalyst tablets prepared had the compositional make-ups crush 
strength and the resistance to attrition as shown in Table 6. 
The results of the conversions of isobutylene in both Examples 24 and 25 
are also shown in Table 6. 
EXAMPLE 26 
Procedures identical to those used in Example 15 were carried out, except 
that no zirconium nitrate was employed. 
The results of Example 26 are shown in Table 6. 
EXAMPLE 27 
Procedures identical to those used in Example 25 were conducted, except 
that neither ammonium metavanadate nor stannic oxide were employed. 
The results of Example 27 are shown in Table 6. 
Table 6 
__________________________________________________________________________ 
Resistance 
Conversion 
Selectivity 
Composition of catalyst Crush to of to Yield of 
Example 
(Atomic ratio) strength 
attrition 
isobutylene 
methacrolein 
metharcrolein 
No. Mo Co Fe Bi Cs X Y (kg/tablet) 
(% by weight) 
(%) (%) (%) 
__________________________________________________________________________ 
14 12 8 2 1 0.005 
V = 0.1 
Ti = 1 
6.5 0.03 95.3 89.9 85.7 
15 10 8 2 1 0.01 
V = 0.1 
Zr = 1 
6.8 0.02 94.9 89.0 84.5 
16 10 8 3 1 0.005 
V = 0.2 
Sn = 2 
6.2 0.04 97.3 87.0 84.7 
17 10 8 3 1 0.01 
V = 0.1 
Ni = 1 
6.6 0.03 97.0 87.4 84.8 
18 10 8 2 1 0.01 
V = 0.1 
Zr = 1 
6.4 0.02 98.9 86.3 85.4 
Sn = 1 
Ti = 1 
19 10 8 2 1 0.01 
V = 0.2 
Sn = 1 
6.8 0.02 95.9 87.1 83.5 
20 10 8 2 2 0.05 
Pd = 0.1 
Ti = 1 
7.3 0.02 94.3 89.1 84.0 
21 10 8 3 2 0.01 
Pd = 0.2 
Zr = 2 
6.4 0.05 97.6 87.2 85.1 
22 10 8 2 1 0.01 
Pd = 0.1 
Sn = 2 
7.1 0.01 96.8 87.0 84.2 
23 10 7 3 0.5 
0.01 
Pd = 0.1 
Ni = 2 
6.0 0.06 95.3 88.2 84.0 
V = 0.1 
24 10 8 2 1 0.01 
Pd = 0.1 
Ti = 1 
5.9 0.03 98.1 86.0 84.4 
V = 0.1 
25 10 8 2 0.5 
0.01 
Pd = 0.1 
Sn = 2 
7.3 0.04 96.5 88.8 85.7 
26 10 8 2 1 0.01 
V = 0.1 
0 5.0 0.25 92.8 86.7 80.5 
27 10 8 2 0.5 
0.01 
Pd = 0.1 
0 5.3 0.31 95.8 84.4 80.9 
__________________________________________________________________________ 
From a comparison of the results of Examples 14 through 25 with those of 
Examples 26 and 27, it is clear that the use of a further additional 
catalytic ingredient consisting of at least one member selected from 
titanium, tin and zirconium causes the crush strength and the resistance 
to attrition of the catalyst tablets to be enhanced and the yield of 
methacrolein to be increased. 
COMISON EXAMPLES 20 THROUGH 27 
In each of Comparison Examples 20 through 27, the same procedures as those 
described in Example 14 were carried out, except that the preparation of 
the catalyst was effected in such a manner that the resultant catalyst had 
a composition, as shown in Table 7, which composition is outside of the 
scope of the present invention. In each of Comparison Examples 21 and 27, 
the contact of the feed gas with the catalyst was carried out at a 
temperature of 370.degree. C. 
The results of Comparison Examples 20 through 27 are shown in Table 7. 
Table 7 
__________________________________________________________________________ 
Composition of catalyst 
Comparison 
(Atomic ratio) Conversion of 
Selectivity to 
Yield of 
Example Alkali isobutylene 
methacrolein 
methacrolein 
No. Mo Co 
Fe 
Bi 
metal X Y (%) (%) (%) 
__________________________________________________________________________ 
20 10 8 3 1 0 0 Ti = 2 
86.5 68.2 59.0 
21 10 8 2 1 0 V = 0.5 
Sn = 1 
92.6 73.1 67.7 
22 10 8 3 1 0 Pd = 0.1 
Zr = 1 
95.2 69.8 66.4 
23 10 8 2 1 0 Pd = 0.1 
Ni = 1 
93.8 65.7 61.6 
24 10 8 2 2 0 0 Zr = 3 
91.3 74.1 67.7 
25 10 8 2 2 Cs = 0.01 
V = 0.1 
Ti = 7 
68.4 89.3 61.1 
26 10 8 2 1 Cs = 0.005 
0 Ti = 1 
90.3 85.1 76.8 
27 10 8 2 1 K = 0.05 
V = 0.1 
0 97.4 68.1 66.3 
__________________________________________________________________________