JPS6045859B2 - Method for producing methacrolein and methacrylic acid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for producing methacrolein and methacrylic acid by contacting a mixture containing isobutylene and oxygen with a catalyst in the hot gas phase.

The catalytic oxidation of propylene or isobutylene to the corresponding unsaturated aldehydes and unsaturated fatty acids is well known. The present inventors have previously discovered a catalyst that is effective for catalytic oxidation of olefins having 3 or 4 carbon atoms.

(JP-A-50-13308, 50-95206) Although the reaction results of the above catalysts are very good, they have the drawback that the reaction temperature is relatively high, and furthermore, the yield of the target product can be further improved. It was desired to do so. As a result of intensive studies on improving the above-mentioned catalyst, the present inventors found that by adding cobalt to the above-mentioned catalyst and further adding at least one element selected from selenium, zinc, and vanadium, the reaction temperature can be significantly lowered and the desired product can be achieved. The present invention was achieved by discovering a new fact that the yield of .

That is, the method of the present invention uses the general formula M0aSbbBic
FedNieC0fXgYh0.

This is a method of vapor phase catalytic oxidation of isobutylene using a catalyst represented by: In the above formula, X is potassium, rubidium, cesium and/or thallium, and Y is at least one element selected from selenium, zinc, and vanadium.

a, b, c, d, e, f, g and this indicate the atomic ratio of each element, where a is 12, and is 0.2 to 20,
c■0.2-12, d■0.2-12, e■0.2-1
2, f■0.2~12, g■0.01~4, re■0.0
1 to 4, and i is a value determined by the oxidation state of the catalyst.
The catalyst of the present invention can be prepared by known methods.

As a molybdenum source for preparing a catalyst, an oxide or a compound that becomes an oxygen substance when ignited is desirable. Such compounds include ammonium molybdate and the like. In this catalyst, the effect of adding the antimony component is extremely large, and by adding antimony, the catalyst performance increases dramatically.

As the antimony source, oxides, hydrous oxides, chlorides, etc. are preferable. As sources of other component elements, oxides or compounds that become oxides upon ignition, such as nitrates, carbonates, and hydroxides, are preferred.

A carrier can be used in preparing the catalyst. Silica, alumina, silicon carbide, etc. are used as the carrier. When carrying out the reaction of the present invention, it is preferable to use isobutylene as a raw material after diluting it with an inert gas.

Nitrogen, water vapor, carbon dioxide gas, etc. are used as the inert gas, and water vapor has a particularly favorable effect on improving the yield. Air or oxygen-enriched air is used as the oxygen source for oxidation. The concentration of isobutylene in the raw gas mixture is between 1 and
It can be changed within a range of 2%. The concentration of oxygen is also 1
It can be varied in the range of ~20% by volume. The reaction pressure used is from normal pressure to several atmospheres. The reaction temperature is 200~
The temperature is preferably 450°C, particularly 250 to 400°C, and the contact time is preferably in the range of 0.5 to 1 stroke. The reaction can be carried out in a fluidized or fixed bed. EXAMPLES The present invention will be specifically explained below with reference to Examples.

Parts in Examples indicate parts by weight. Moreover, the yield means the following.

Example 1 29.3 parts of antimony trioxide was suspended in 200 parts of water,
To this, 176.6 parts of ammonium molybdate was added to 10 parts of water (1
) and then add 8.1 cesium nitrate.
80.8 parts of bismuth nitrate dissolved in 100 parts of 10% nitric acid, 67 parts of ferric nitrate
Part J, 145 parts of nickel nitrate, 48.6 parts of cobalt nitrate and 12.4 parts of zinc nitrate dissolved in 5(1) parts of water were added, and finally the silica part was added in the form of silica sol.

The obtained slurry was evaporated to dryness, dried at 120°C, molded, and calcined at 500°C for 6 hours under air circulation to prepare a catalyst.

The composition of this catalyst is MOl2Sb2Bi2Fe2Ni6C
O2CSO,5znO. It was 5.

Using this catalyst, the temperature of the catalyst layer was maintained at 360°C, and a raw material mixed gas of 5% isobutylene, 12% oxygen, 48% nitrogen, and 35% water vapor was added to it for a contact time of 3. Passed with mark 2.

Analysis of the product was performed by gas chromatography, and the total yield of methacrolein and methacrylic acid was 83
．． It was 0%. The reaction was continued for about 200 hours under the same conditions, and a total yield of 83% was maintained during this period, resulting in stable operation. Example 2 Potassium nitrate 2 was used instead of cesium nitrate in Example 1.
．． A catalyst was prepared that differed only by the addition of 53 parts and 11.1 parts of thallium nitrate.

The composition is MOI2Sb2Bl2Fe2Nl6CO2KO.
5TeO. ,znO. It is 5.

Using this catalyst, the temperature of the catalyst layer was maintained at 360° C., and the reaction was carried out under the same conditions as in Example 1 except that a total yield of methacrolein and methacrylic acid of 82.5% was obtained. Example 3 In Example 1, zinc nitrate was not added, and selenium dioxide 4.
6? A catalyst was prepared that differed only by the addition of .

The composition is MOl2Sb2Bl2Fe2Nl6CO2CSO
．． 5SeO. It is 5. Using this catalyst, the temperature of the catalyst layer was maintained at 350° C., and the reaction was carried out under the same conditions as in Example 1 except that a total yield of methacrolein and methacrylic acid of 82.5% was obtained. Example 4 In Example 1, cesium nitrate was not added, and 6.15 parts of rubidium nitrate and 5.7 parts of ammonium metavanadate were added.
A catalyst was prepared that differed only by adding 5 parts.

Composition is MOl2Sb2Bl2Fe2Nl6CO2RY)
. ．． 1■. 5V0.6. Using this catalyst, the temperature of the catalyst layer was maintained at 350° C., and the reaction was carried out under the same conditions as in Example 1 except that a total yield of methacrolein and methacrylic acid of 82.0% was obtained. Example 5 54 parts of antimony 5 oxide were suspended in 20 CB of water, to which was added 176.6 parts of molybdenum ammonium dissolved in 10(1) parts of water, and then 2.53 parts of potassium nitrate and 3.70 parts of rubidium nitrate. 15 parts dissolved in 15 parts water,
40.4 parts of bismuth nitrate dissolved in 5 parts of 10% nitric acid, 101 parts of ferric nitrate, 97 parts of nickel nitrate, 24.3 parts of cobalt nitrate, and 12.4 parts of zinc nitrate were mixed with 5 parts of water (1 part).
) was added to the solution, and Kabe was added in the form of silica sol.

The obtained slurry was evaporated to dryness, dried at 120°C, molded, and calcined at 500°C for 6 hours under air circulation to prepare a catalyst.

The catalyst composition is MOL.

Sb4BllFe3Ni4COlKO. 3RbO. Rl
O. It was 5. When a reaction was carried out using this catalyst under the same conditions as in Example 1, the total yield of methacrolein and methacrylic acid was 82.0%.

Example 6 A catalyst was prepared that differed from Example 1 only in that 4.21 parts of potassium nitrate was used instead of 8.1 parts of cesium nitrate.

The composition of this catalyst is MOI.

Sb2Bl2Fe2Ni6CO2KO. ! NO. It is 5. A reaction was carried out using this catalyst under the same conditions as in Example 1,
Total yield of methacoololein and methacrylic acid 82.
Obtained 2%. Comparative Example 1 A catalyst was prepared in Example 1 except that no zinc nitrate was added.

Using this catalyst, a reaction was carried out under the same conditions as in Example 1, and as a result, the total yield of methacrolein and methacrylic acid was 79.0%. Comparative Example 2 A catalyst was prepared in Example 1 except that antimony oxide was not added.

Using this catalyst, a reaction was carried out under the same conditions as in Example 1, and as a result, the total yield of methacrolein and methacrylic acid was 65.0%. Comparative Example 3 A catalyst was prepared in Example 1 except that antimony oxide and zinc nitrate were not added.

Claims (1)

[Claims] 1. A method for producing methacrolein and methacrylic acid, which comprises bringing a mixed gas containing isobutylene and oxygen into contact with a catalyst represented by the following general formula in a high-temperature gas phase. Mo_aSb_bBi_cFe_dNi_eCo_fX
_gY_hO_i However, in the formula, X is potassium, rubidium, and/or cesium, or thallium thereof, and Y is at least one element selected from selenium, zinc, and vanadium. Moreover, a, b, c, d, e, f, g and h indicate the atomic ratio of each element, and when a=12, b=0.2 to 20
, c=0.2~12, d=0.2~12, e=0.2~
12, f=0.2-12, g=0.01-4, h=0.
01 to 4, and i is a value determined by the oxidation state of the catalyst.