JPS58113141A - Manufacture of methacrolein - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing methaklein, and more particularly to isophthylene and t-butyl alcohol? This paper relates to the production of methacrolein by gas phase oxidation.

As is well known, unsaturated aldehydes such as acrolein and methacrolein can be prepared by gas phase oxidation of the corresponding olefins with molecular oxygen in the presence of a suitable oxidation catalyst. A wide variety of catalyst compositions have been proposed for this purpose, many of which consist in particular of oxides of molybdenum, iron and bismuth. Generally, however, the selectivity to the target aldehyde, ie the number of moles of aldehyde obtained per mole of olefins converted, is relatively low when using this type of catalyst. Recently, attempts have been made to increase the selectivity of the reaction by incorporating oxides of rather uncommon elements into the catalyst.

US Pat. No. 4,087,382 describes improved catalysts containing molybdenum, bismuth, iron, cobalt, thallium, antimony and sometimes silicon. The yuzu catalyst was found to have improved performance over prior art catalysts. However, when this type of catalyst is used at pressures higher than atmospheric pressure, as is commonly practiced, results are obtained which are inferior compared to performance when operated at atmospheric pressure. There was still a demand for further improvements. As an industrially useful catalyst, it was desired to restore the performance lost when operating at pressures higher than atmospheric pressure. Furthermore, improvements in the long-term stability of the catalyst were also observed in R4.

The present invention has a composition similar to that of the catalyst described in U.S. Pat. Become.

Describing the prior art regarding catalysts used in the oxidation of lower olefins to produce unsaturated aldehydes is difficult because of the large array of elements that have been found useful by many researchers. With respect to the catalyst compositions described below, the following US patent specifications are believed to be particularly useful resources: US Pat.

US Pat. No. 4.034.008 states that potassium e
Contains carbon steel, molybdenum, bismuth, iron, cobalt and (
It also describes a catalyst containing nickel, antimony and/or ruthenium and optionally traces of chlorine. do not.

This specification extensively describes the oxidation of alpha-beta unsaturated monoolefins to produce the corresponding aldehydes or carboxylic acids or the ammoxidation of these monoolefins to produce the corresponding nitriles. However, the examples only describe the production of acrolein by oxidizing zolopyrene. It should be noted that although propylene and imbutylene are chemically related, the oxidation of imbutylene (or its equivalent compound, t-butyl alcohol) is a more difficult reaction to carry out than the oxidation of zolopylene. This is what is being considered. Catalyst is 400-55
Although it is described that calcination is performed at 0°C for 2 to 24 hours,
Example 1d shows a catalyst calcined at a temperature of 450-490°C. The catalyst is preferably silica, alumina,
It has been described that it is supported on carriers such as silicon carbide, zirconium oxide and titanium oxide.

The importance of the use of thallium is explained in U.S. Pat. No. 3,951.
This is pointed out in the specification of No. 861. In the same specification, the criticality of thallium content is found in molybdenum, bismuth, iron, cobalt and/or magnesium and/or manganese,
It is described in connection with catalyst compositions consisting of nickel and optionally phosphorous and other metal groups, in particular copper, calcium, strontium, zinc, cadmium, tin and lead. The catalyst described in this percentage specification does not contain antimony, alkali metals or rare earth-metals. This patent is specifically directed to the oxidation of propylene to acrolein, whereas related U.S. Pat. No. 3,928,462 is used to oxidize isobutylene to methacrolein. The need for small amounts of thallium in similar catalysts is described. These catalysts are generally calcined at temperatures of 525-550°C.

Preferably, these catalysts are supported on supports such as silica, alumina, silicon carbide and titanium oxide.

Nickel is used as a catalyst in many catalysts, particularly in the aforementioned U.S. Pat.
No. 1.861 and No. 4.034. It is used in the catalyst described in OO8. U.S. Patent No. 3,454
．． No. 630, Meiho No. 1 So, emphasizes the advantages of oxides of nickel and cobalt.

This patent specification considers nickel and cobalt to be equivalent and proposes that either one can be used. The catalyst described herein does not contain thallium, antimony, silicon and alkali metals contained in the catalyst of the present invention and requires the presence of phosphorus. Example 41 of the above-mentioned patent specification shows relatively low catalytic performance in terms of selectivity to methacrolein.

U.S. Patent No. 4.034.008 (described in III), U.S. Patent No. 3
, 186.955 and 3.855.308, silicon is also indicated to be a useful component of this type of catalyst. U.S. Patent No. 3.
The catalyst of No. 186.955 is preferably barium,
and bismuth in an amount greater than molybdenum, and does not contain iron, cobalt, thallium, antimony, nickel, and alkali gold F4f contained in the catalyst of the present invention.

This catalyst is described for use in a number of purposes, including the oxidation of isobutylene to methacrolein.

It has been pointed out that calcination above about 565°C is fatal to the performance of the catalyst. Although the catalyst of U.S. Pat. temperature is used.

British Patent No. πF No. 1.456.752 Specification 1 is the foundation base
It is described that the performance of a catalyst made of molybdenum, bismuth, cobalt and iron is improved by adding antimony. This patent teaches that antimony has the effect of modifying the selectivity to methacrolein, but that calcination of the catalyst at temperatures of 500-550°C reduces the catalyst activity. In such cases, at least one known element selected from a wide range of elements including barium and nickel is added to restore some of the activity lost by adding antimony. The patent specification further states that the catalyst is 600 to 700
It is stated that the activity can be improved by calcination at a temperature of °C. Alkali metals and/or thallium can be added to such catalysts.

In that embodiment, the catalyst is generally mixed with silicon carbide powder as a carrier. This patent states that pressure is not critical to this reaction. This patent specification 1-1' does not give any information regarding the surface area and pore size of the catalyst described. Furthermore, it does not contain silica as a catalyst component.

In general, it appears that the composition of this type of catalyst cannot be predicted simply by combining the many elements described in the prior art, and that catalyst performance must be determined experimentally at the expected operating conditions. . Small changes in composition are therefore of great importance in improving catalyst performance, particularly in optimizing catalyst composition for a particular reaction and set of operating conditions.

As will be seen from the description of the invention that follows, changes in operating conditions and manufacturing methods may result in deterioration of catalyst performance, and components may have to be added to the catalyst to restore performance loss.

The conversion of isobutylene and/or tert-butyl alcohol to methacrolein with high selectivity requires oxides of molybdenum, cobalt, iron, bismuth, thallium, antimony, silicon and nickel as well as alkali metals, alkali It has been found that this can be achieved by carrying out the gas phase oxidation with molecular oxygen in the presence of a catalyst composition comprising one or more oxides of the entire earth group, rare earth metals including lanthanum, and tungsten.

The catalyst composition used in the method of the present invention has the following general formula % (where X is one member of the group consisting of alkali metals, alkaline earth metals, all rare earths including lanthanum, tungsten, and mixtures thereof. ], a=12,
b=0.2~8, cO,05~5, d=0.
2-4, e ~0.01-5, f ~0.01
~5.

g=i~20. h=0.05 to 5, 1 is a positive numerical value up to 4, and j is a numerical value that changes depending on the valence and composition ratio of other elements.

More specifically, a more preferred catalyst for use in the process of the invention comprises an oxide of a particular element in an atomic ratio of M o =
12, C0=4, Fe=3, Bi=1, T/==0.5
．． 5b=0.3.5i=6.6, N1=2, Cs=
0.3 and K = 0.3 based on the composition of the stock solution. The catalyst composition can be considered as a mixture of oxides of the aforementioned elements or as an oxygen-containing compound of the elements, and when the term "mixture of oxides" is used it is understood to include each or both. Should. When used and under (or Fi) reaction conditions, the catalyst can include each form or both.

The catalyst can be prepared by methods well known in the art, but
Calcining is carried out at temperatures higher than those commonly used in the past, ie at least 525°C or higher, preferably 550°C or higher. The catalyst of the present invention, which has been calcined for a sufficient period of time, has a molecular weight of about 0.5 to 10-/2, preferably about 2 to 6 tr?
/l BET surface area, pore volume associated with pores smaller than about 100X is about 10% or less, preferably 1L<Fi3%
The present invention is based on the general formula % (wherein, A, a=
12, b = 0.2~8 p c = 0.5~5 d
~0.2~4. e=0.0] ~5. f=(11) 0.01~5 t g=1~20. h=0.05～
5. l is a positive number up to 4), j is a number that changes depending on the valence and composition ratio of other elements),
Moreover, the BET surface area of catalyst 1 is approximately 0.5 to Iorr.
? The present invention provides a method for producing methacrolein, which comprises gas phase oxidation of isobutylene and/or t-dityl alcohol with molecular oxygen in the presence of a catalyst composition.

(I29 The catalyst composition is calcined at a temperature of at least 525°C for a time sufficient to reduce the BET surface area to about 0.5-10 m'' for catalyst 12. Preferably the BET surface area is about 2-6 m'' /f, and approximately 3% or less of the surface area is 10OA
The pores have a smaller diameter. The BET surface area is
Brunauer.

[Journal of the American
Chemical 5ociety J 60, 3
09 (1938) by the nitrogen adsorption method described on gQ. Pore diameter and pore volume are described by Drake and Rlter in “The Analytic
al Edition ofIndustrial E
ngineering ChemistryJ 17
, 787 (1945). Surface area, pore size and pore volume are often calculated according to TeE: mmet and Dewitt. )
“The An-analytical Edition
of Industrial Engineering
gChemlstry, J 13, 28 (1841
) is correlated with the equation given by

The catalyst composition is preferably used in the form of pellets or other compression molded forms of various sizes. The compositions can be prepared in a conventional manner using techniques well known to those skilled in the art. For example, compounds of molybdenum, cobalt, iron, thallium, antimony, bismuth, cesium, potassium, and nickel are each dissolved in a small amount of water or other catalyst, these 7 solutions are combined with colloidal silica, and the mixture is evaporated to dryness. 61. To prepare the catalyst, several components can be introduced into the solution in the form of salts or other compounds in convenient form, and the precursors of the catalyst can be introduced into the solution.
9. Must be limited to a special form as (sor). There isn't. However, particular preference is given to using the elements to be supplied in the form of ammonium salts, halides, such as chlorides, nitrates or acids. Preferably, a water bath liquid is used and water soluble forms of the elements are used, except that the silica portion in the catalyst is normally insoluble. In some cases, acids and/or bases may be added to the solution to aid in dissolving the catalyst precursor. For example, in some cases an acid such as hydrochloric or nitric acid or a base such as ammonium hydroxide may be used. The silicon may be added in the form of an aqueous colloidal solution of sio, dispersed in water or alcohol. Representative suspensions of colloidal silica particles obtained from Nalco ChemicnlCOo (trade name Nalcoag) and E.

■. Available from Du Pant (trade name Ludox).

Powdered colloidal silica is available from Degusga (trade name Aarosil). The particle size is 50 n? / f l) about 6001 to 750 m'/f (!'JBET %face') with E T surface species
This is the size at 40 At.tm.

The powder produced after evaporation is thoroughly dried and preferably K-sieved to remove large particles that would interfere with forming a uniform compacted form, eg a pellet. Typically, the powder passes through a Tyler 20 mesh sieve. The powder is then mixed with any conventional organic binder, such as polyvinyl alcohol, and the mixture is thoroughly dried and sieved once, such as Tyler's 20-80
Meh. ,,,love. Grain + □□ZOc*L,
Preferably any conventional type for the first time.
c'J lubricant, such as stearic acid or perilla graphite, and formed by compression molding, e.g., into pellets, extrusion, or any other method, and the shaped catalyst typically has a 9.5 inch (1/16 to 3/8 inch)
height and 1n diameter f. The shaped catalyst composition is then activated by heating at temperatures higher than those commonly used for piggyback technology catalysts and for the length of time necessary to obtain the desired BET surface layer. For example, typically the pellets are placed in a furnace, kiln or tube and blown with 2 to 1 liters of air at both temperatures, e.g. at least 525°C, preferably above 550°C.
Pass for O hours. A particularly preferred activation step involves increasing the temperature to 20
Raise to 600°C at a rate of 6C/hr and hold at 600°C for 3 hours.

wMIM of a catalyst in a form suitable for use in gas phase oxidation reactions
The foregoing description of the process is merely one example of many possible preparation methods, and is intended solely for the purpose of illustration, except that the calcination portion of the process forms an essential component of the invention. You can understand that.

However, the method described in 1viJ is the preferred method for %.

The catalyst of this invention, invention 4, is tuptylene and (also 1j) t.
- Suitable for oxidizing butyl alcohol to methacrolein.

When the catalyst of the present invention is used in the production of methacrolein by gas phase oxidation of isobutylene and/or 1-butyl alcohol, the operating conditions used are those generally relevant for this reaction. Therefore, the catalysts of the present invention are particularly useful for reactions that give high selectivity with isobutylene and/or t.
- contacting butyl alcohol in the gas phase in the presence of molecular oxygen and preferably steam in the presence of a catalyst.

Once the reaction starts, it becomes a self-sustaining reaction because it is an exothermic reaction. It has been found that a variety of reactors can be used, with a common reactor of the shell-and-tube heat exchanger type, in which the catalyst pellets are packed inside the tubes, giving satisfactory results. The process can also be carried out in equipment commonly used for reactions of this type.

The gaseous feedstock fed to the reactor contains isobutylene and/or t-butyl alcohol, oxygen and steam. Typically, an inert gas such as nitrogen is also present. Usually Flk:Ait is added as is or as air or air with oxygen added.

As mentioned above, conventional oxidation conditions can be used, but for best results, isobutylene and/or t-butyl alcohol should be present at about 2-20% by volume of the total feedstock.
, preferably at a concentration of about 5-15% by volume, whereas oxygen is limited by the explosive limit of the mixture, but at a concentration of about 4-15% by volume.
30% by volume, preferably 10-20% by volume, steam F
The amount is within 30% by volume, preferably 5-25% by volume, and the remainder is an inert gas or an inert gas mixture.

Reaction temperature for best results is approximately 250-500°C
, preferably 300-400°C, optimally 310-37
It should be 0°C. Since the reaction is exothermic, methods are used to remove the heat, such as surrounding the area containing the catalyst pellet with a salt bath or Vis water.

The pressure inside the reactor affects catalyst performance as well as speed. The reaction can be carried out at normal pressure, above or below atmospheric pressure, but preferably between normal pressure and absolute pressure of 15.1 -/-
1 preferably absolute pressure 8 to 9/a+! .

Optimally pressures within 6.3 IC9/ctA absolute are used. Typically, absolute pressure is 3.4 kg/t
A pressure of f/i is used.

The methacrolein produced can be recovered by various methods known to those skilled in the art.

For example, methacrolein can be condensed or scrubbed with water or other suitable hot medium, and unsaturated aldehydes can then be separated from the scrubbed liquid. The residual gas Vi remaining after the methacrolein removal step can optionally be recycled to the reaction system; in this case,
The net amount of CO produced by the reaction! can be removed by conventional methods, such as absorption into a carbonate water bath, or purged from the reaction system.

The features of the present invention will be easily understood from the following examples. However, it goes without saying that these examples are for the purpose of illustrating a single button and should not be construed as limiting the invention.

Reference example 1 (prior art) Water 750 CCK (N114) 111V10?0!4
, 4klzO636f tokas o Next 4CCo (No.
s) * -6HzO262f f water 300CC [,
Fe(Now)s, 9HsO60,6y with water 200
CC4C.

Tha Om 68.4 t water 10cc and coating Hct
To 30 cc of the mixture, Bl (N0s) m,
Dissolve in a mixture of 200 cc of sa, of water, and 50 cc of concentrated nitric acid. Add enough ammonium hydroxide to the solution to make the solution 4f7. Add these bath solutions to a volume of 4
The mixture in the dryer is evaporated to dryness and raised to a temperature of 300°C. The resulting powder is taken out of the dryer and dried in a heating oven at 400°C for 12 hours.

Sieve the dry powder through a 20 mesh sieve and add 4% of polyvinyl alcohol as needed to form a moist mass.
A water bath solution is added and the mixture is dried at 75-80°C until the water content in the mixture is 2-4%.

The dry mixture is then sieved through a 20-60 mesh sieve and about 2% stearic acid powder is thoroughly incorporated into the mixture. The resulting mixture is then shaped to a height and diameter of 4.8 a.
m (3/1 5 inch) pellets and activated in a furnace by gradually heating the pellets at a heating rate of 20° C./hour to about 380° C. and holding at this temperature for 16 hours. The activated pellets have a density of 0.95 t/cc and a surface species of 6.5 m''/f. The catalyst components molybdenum, cobalt, iron, thallium, antimony, and bismuth absorb violet in the raw solution. 12 each as a standard
．． 3.0.5.1.1 and 1.5 atomic ratios are shown.

5 occ of this catalyst composition was placed in a reactor formed by a 12.7 x 2.743 mm steel tube, and
1 inert filler (silicon carbide) 30 on the bottom of the floor)
0CC is charged above the catalyst bed with enough inert packing to fill the reactor. Nitrogen diluted mixture containing 9% by volume isobutylene, 10% by volume oxygen and 20% by volume steam total approximately 1 atm, 360-370°C
and a space velocity of about 3000/hour. The term "space velocity" as used herein is used in the usual sense, and refers to the number of tons of gas per hour per ton of catalyst per hour under standard conditions. The reaction was operated by continuously introducing the raw material gas and continuously withdrawing the exhaust gas. analyzed using gas chromatography. Both methacrolein and methacrylic acid are useful, so the sum of both is reported.

Methacrolein is also generally oxidized for 111 minutes in a separate reactor to produce further methacrylic acid, which is converted, for example, to methyl methacrylate. The main product in the mixture is methacrolein, and the content of methacrylic acid is only about 2-3% of the total amount shown below.

The experimental results are shown in Table 1.

Reference Example 2 A test was conducted using a catalyst having the same composition as the catalyst of Reference Example 1 and having a surface area of 5.6 m/.9.

The reaction pressure was increased to 3.46 kg/(3d), resulting in a decrease in conversion and selectivity to methacrolein as shown in Table 1I.
00/hour, and the gas composition was essentially the same as Reference Example 2 except that 8.5% by volume t-butyl alcohol (TBA) was used in Reference Example 1 instead of the isobutylene raw material.
Therefore, the composition of the gas after dehydration was 7% by volume of isobutylene, 9.8% by volume of oxygen, 20% by volume of steam, and the remainder phosphorus. The reaction temperature was 335-340°C.

As can be seen by comparing Table 11 and Table 1■, as the reaction pressure increases, the selectivity to the target product methacrolein decreases, and the η11 products acetic acid and CO/CO
, the catalyst performance deteriorates as indicated by the increase in . Since the conversion is low in this reference example, the selectivity would be expected to be higher than the selectivity in Table 1, assuming that increasing the pressure had no effect. Although the catalysts in Table 1 and the catalysts in Table 1 had not been used for long periods of time, and therefore there was no change in performance to some extent over time, deterioration in performance at high pressures was observed. We conclude that the reaction of oxidation of inbutylene and its equivalent, t-butyl alcohol, to methacrolein is sensitive to increases in pressure within this relatively low range. You can also do it. (As can be seen, pressures higher than atmospheric pressure are normally used, and the absolute pressure of 3.46 used in Reference Example 2
The pressure in kg/cl is the more realistic value for industrial practice.

Reference Example 3 Reference Example 2 is repeated except that the catalyst is heated to about 600°C instead of the 380°C used in Reference Example 2 when preparing the catalyst. The surface area of the catalyst is 2.4rrll&, and the composition of the raw material gas is TBA 5.7% by volume, oxygen 9.8% by volume,
Steam 20 yen was left for purchase. 33-36%
It was found that a temperature of 435-445° C. was required to obtain a conversion of about 75.5% and a selectivity to methacrolein + methacrylic acid of about 75.5%. The selection rate for CO+CO* is approximately 2
It was 0%.

Therefore, instead of 380℃ used in Reference Example 2, 600℃
If the catalyst is heated to a certain temperature, the catalyst performance will deteriorate considerably.

Example 1 Dissolve molybdenum salt (NH4), Mo, 4-41"l!0636.9 in 750 cc of water, then dissolve 400 cc of water.
cc KCo (NO3)1-6H,03499, water 400 cc Ic Fe (NO3)se9)1.
03639, N1 (No3), 6H in 300CC of water
,0175g, water 400 CCK TlN0s40
/J, 100 cc of water, 17.4 g of K CsNO, 6 g of KOH in 50 cc of water, 30 cc of water, and m HC
II 5bC7320, 4g in 10 cc of mixed liquid,
Add Bi(N) to a mixture of 100 cc of water and 25 cc of concentrated nitric acid.
03)! - Dissolve 5H, 0145, 9 respectively and add 40% colloidal dioxygen dioxide (E, I, Du Font de Nemo-urs
with an average particle size of 120 A and a BET surface of 232
rrl/,! Ludox H840% with i'
) Added 300y. Ammonium hydroxide was added in an amount to bring the pH of the mixture to 7, and then the mixture was evaporated to dryness.

The method described in Reference Example 1 was followed except that the pellets were activated by heating to about 340°C at a heating rate of 20°C/hour, then rapidly heated to 600°C and held at that temperature for 2.5 hours. A pellet was prepared.

The atomic ratio of the generated catalyst is based on the composition of the initial solution M: 12 molybdenum, 4 cobalt, 3 iron, 1 bismuth, 0.5 thallium, 0.3 antimony, 6.6 ion, 2 nickel, and cesium. 0.3 and potassium 0.3. During activation the surface area from 23rrt/g to 5,1 rrl/
decreased to ji.

The catalyst required approximately 335 to obtain the excellent results shown in Table 111.
The test was conducted under the conditions of Reference Example 3, except that only a temperature of .degree. C. was required. The catalyst showed superior results to the results of Reference Example 2 and to the results of Reference Example 1, which was carried out at a more preferred pressure of 1 atmosphere.

Table 10 The catalyst of Reference Example 1 to which nickel, silica, cesium, and potassium were added exhibits superior performance compared to the prior art catalyst of Reference Example 1 even under the more severe condition F of Reference Example 3. I understand.

Example 2 Similar results are shown in Table IV below when a catalyst having the same composition as in Example 1 was prepared, except that the atomic ratio of silicon was increased from 66 to 12.

The surface area of the catalyst was reduced from approximately 23 nX/9 to 7.8 rl/g by heating to 600 °C during catalyst preparation. Unlike the actual example mentioned above, the composition, pressure, and space velocity of the raw gas were changed during the test run.

Comparative Example 1 A catalyst composition obtained by removing the nirathyl content from the composition of Example 1 was tested under the same conditions as in Example 1, and the effect of nickel on the catalyst of the present invention is shown in Table 7 below.

Table V As can be seen from a comparison of Tables 11 and 7, when the catalyst is devoid of nickel, the conversion of t-butyl alcohol decreases by IM as measured, directly or indirectly by the temperature required for the reaction. as shown in . The surface area of this catalyst is 4.8.7 g.

Example 3 Using calcium instead of potassium and cesium,
Ca (C1H30,) -H,052.8g in water 20
Based on the stock solution, according to Example 1 except that calcium was introduced into the mixture by dissolving it to 0 cc and adding it to the mixture.
Catalysts with the following compositions were prepared: bo, a 8js, and a Cas Q j. During calcination, the catalyst was heated at about 600° C. for 3 hours to reduce the surface area from about 2 (Jtrt/El to 5 m/g). Raw material gas with the composition of the remaining ρ hydrogen, absolute pressure 2,44
It was tested at a pressure of kg/air and a space velocity of about 22,507 hours with the following results.

Table ■ Example 4 La (NOx)a ・5umo 124 i in water 3
00 cc, composition MoB Co4 k'eB B 71 Tuo, s 8, based on the IiL bath liquid, according to example 1 except that lanthanum was introduced into the catalyst in addition to the mixture.
bo,, S i6. , Nl, Lal-Cs
A catalyst with o, 8 Ko, 30 j was prepared.

Example 5 (NH4)a Wy 0w4.H,076.2g was dissolved in 300 cc of water and added to the mixture, and the composition Mol. , Co4 Fe5BjI T7648b6,3
8 i6. @NilWl-CsO,,KO,3
A catalyst with 0j was prepared.

In addition to the effect of changing the catalyst composition, the surface area of the catalyst measured by the BET method shows a relatively narrow range, i.e. 0.
It seems important to keep it between 5 and 10 g, preferably between 2 and 6 ml.

Surface area is related to pore size, since particles with many small pores have a large surface area, while particles containing only large pores have a relatively small surface area.

Heating the catalyst at a temperature of at least 525°C, preferably 550°C or higher, for a sufficient period of time appears to eliminate porosity and thus reduce surface area.

Preferably, the catalyst is calcined at about 600° C. before use, but as shown in Example 6 below, the surface area of the resulting catalyst is reduced to about 1
0 m'/, 9 or less, preferably about 6-/9 or less, at a somewhat lower temperature, at least about 525°C.
This can be done by calcining.

Example 6 Based on the raw solution according to Example 1, the composition MO! ,l
CO4Fed B iI Tl01B sbO,,s
A catalyst with i,...Ni1csO,ll-KO,,Oj was prepared from i11#. Approximately 55% during calcination of the catalyst
Heat to 0°C for 3 hours to give a surface area of 9.6g to 7g, 5.
4 volume bi% imbutylene, 938 volume bi% oxygen, 1
Raw material gas with a composition of 6% steam and the rest of the oil, absolute pressure 3.4 ky/cyl, pressure 335%
Tests were conducted using a temperature of 0.degree. C. and a space velocity of about 3000/hour with the following results.

Table ■1 Example 7 Composition Mo12 C04F el B il TJo, s s
The surface area of the catalyst with 0,30j in bO,88t64Ni2Cs6.3- was calcined at temperatures up to 380 DEG C. and a value of 23♂/g was obtained. The pore volume was measured with a mercury pore meter and the value was 0.3 cc/g, and the pore distribution was measured using the same method, and 70% of the internal phase of the catalyst had a pore diameter of 100^ or more, and 30% The result was that the current was less than 100A.

The median value of the pore diameter is 1600A.

A catalyst was prepared under the same conditions as in item 11 except that it was calcined in air at 600°C for 3 hours. The pore volume was the original 0.3 cc/g, while the total surface species was 6.24
m/N, 97% of the internal pores had a pore diameter of 100 A or more, and only 3% had a pore diameter of 100 A.

The effect obtained by heating the catalyst at higher than normal temperatures, as shown in Example 7, reduces the surface area by eliminating pores with diameters smaller than about 100 A, thus increasing the average pore size. There is a particular thing.

Other effects also become important.

Agent Patent Attorney Masaaki Aki Sawa value 1 person =289-

Claims (3)

[Claims] (1) Formula % Formula % (wherein, X is one or more metals selected from the group consisting of alkali metals, alkaline earth metals, rare earth metals including lanthanum, tungsten, and mixtures thereof, B=
l2, b=0.2~8, c=0.5~5,
d=0.2~4 p e=0.01~5, f~
0.01~5,? =1~20. h=0.05~s,i
is a positive number up to 4, and Lj is a value that changes depending on the valence and composition ratio of other elements), and the BET surface area is about 0.5 to 10 m' per 1f of the catalyst. A method for producing methacrolein, which comprises gas phase oxidation of isozotylene and/or Vit-zotyl alcohol with molecular oxygen in the presence of a composition. (2) BE of the catalyst composition at a temperature of at least about 525°C;
2. The method of claim 1, comprising: calcination in air for a period sufficient to reduce the T surface area to a specified value. (3) The BET surface area is about 2 to about 6 per volt of catalyst, and less than about 3% of the surface area of the catalyst is pores having a diameter less than 100 angstroms. the method of.