SU436486A3 - METHOD OF OBTAINING UNSATURATED CARBONIC ACID - Google Patents

Description

one

The invention relates to an improvement in the process for the production of unsaturated carboxylic acid, which is widely used in the chemical and polymeric industry.

A known method for producing an unsaturated carboxylic acid by oxidizing an unsaturated aldehyde in the vapor phase in the presence of a catalyst consisting of reduced metal oxides deposited on aluminum spongy. The yield of the product is 97.5% at a flow rate of 500-1000 hours or 89.5% at a space velocity of 2000. The catalyst must be pretreated at a temperature above the reaction temperature; as the spatial velocity decreases, the yield of the product falls.

In order to increase the yield of the target product according to the invention, a catalyst containing metals of variable valence, chromium and / or tungsten and molybdenum, vanadium, copper is used, in an atomic ratio equal to the pitch 4: pitch 12: 12: 2-14: 1-6, and Preferably, an inert carrier with a specific surface area of not more than 2, with a porosity of 30-65%, in which at least 90% of the pores must have a diameter of 50-100 microns, is used. The process is conducted at a temperature

preferably 200-350 ° C and a pressure of 1-10 atm.

The process is carried out by passing a gaseous mixture of the composition, about. %: 1 -10 unsaturated aldehyde, such as acrolein or methacrolein, 5-15 molecular oxygen, water vapor, and 20-50 inert gas, above the catalyst at a temperature of 200-350 ° C and a pressure of 1-10 atm. The spatial velocity is maintained between 500 and 5000 hours. The reaction can be carried out with both a fixed and a fluidized bed of catalyst.

The yield of unsaturated carboxylic acid in a single pass can be maintained at a high level without reducing the spatial velocity. The catalyst is obtained by well-known techniques, for example, by adding an aqueous solution of ammonium dichromate and an aqueous solution of copper nitrate to an aqueous solution containing ammonium metavanadate, ammonium molybdate, ammonium paratungstate, adding to the carrier mixture and heating the mixture to evaporate to dryness, with these substances. . If necessary, the mixture is pressed to obtain, for example, tablets, which are subsequently calcined at a temperature of 350-600 ° C. As starting compounds for the preparation of the catalyst

Any compound that is capable of forming a catalytic oxide upon calcination can be used, for example, hydrates of oxides or carbonates.

The amount of oxygen present in the oxide catalyst varies with the atomic ratios of the metals in the catalyst, and does not require a special reduction.

Inert porous materials, such as alpha alumina, silicon carbide, pumice, silica, zirconia, titanium oxide, or mixtures thereof, can be used as inert supports for the catalyst.

In the examples given, the terms: degree of conversion, selectivity, and overrun are as follows.

moth unsaturated

reacted

aldehyde

. X 100

moles of injected unsaturated aldehyde

moth received

unsaturated carboxylic acid

Xloo

moth reacted

unsaturated

aldehyde

moth received

unsaturated

carboxylic acid

X100

moth entered

unsaturated

aldehyde

Example 1. When heated and stirred in 5000 ml of water, 104 g of ammonium paratungstate, 86 g of ammonium metavanadate, 338 g of ammonium molybdate and 12 g of ammonium dichromate are charged. Separately, an aqueous solution is prepared containing 86 g of copper nitrate in 300 ml of water, and mixed with the previous aqueous solution. The resulting reaction mixture was poured into a porcelain pulp for evaporation placed in a water bath, and 1000 ml of crushed alpha alumina with a particle diameter of 3-5 mm were added (surface area 1 or 5 less, porosity 42%, not less than 92% pores should have a diameter of 75-250 microns), serving as a carrier. While stirring, the mixture is evaporated to dryness, so that the indicated compounds are deposited on the carrier, and then procave for 5 hours at 400 ° C. A catalyst with the following composition of metals is obtained: Mo) 2, Vi.e. Cu2,2, Sgo, b, W2,4, deposited on alpha-alumina.

5 1000 ml of the obtained catalyst is placed in a v-shaped stainless steel tube with a diameter of 25 mm and the tube is immersed in a bath with molten nitrate heated to a temperature of 220-260 ° C. The tube is inserted

0 gaseous mixture, composition, about. %: acrolein 4, air 55 and water vapor 41 and the reaction is carried out at a spatial velocity of 1000-3000 hours. The results are shown in Table. one.

5 Comparative Example 1a. The experiment described in Example 1 was repeated, with the exception that ammonium vaporized tramate, ammonium dichromate and copper nitrate were not consumed. A catalyst is obtained in which the catalytic oxide of Moi2, V4.6 is supported on an alpha-alumina carrier. When this catalyst is used, the reaction is carried out under the same conditions as in Example 1. The results obtained are shown in Table. one.

Comparative example, 16. The experiment described in Example 1, is repeated, with the exception that iarab, ammonium tungstate and ammonium dichromate are not consumed. With

In this, a catalyst is obtained in which the catalytic oxide Moi2, V4.6, Cu2.2 is deposited on an alpha-alumina carrier. When using this catalyst, the reaction is carried out under the same conditions as in Example 1.

The results are shown in Table. one

Table 1

Examples 2 and 3. Using the catalyst, the preparation of which was described in example 1, the reaction is carried out under the conditions given in example 1, with the exception that the actual speed is set to

4000 hour level (example 2) and 5000 (example 3).

The results are shown in Table. 2

table 2

Examples 4-6. The experiment described in Example 1 was repeated, but the cocTaiB of the gaseous mixture was changed.

Examples 7-9. The experiment described in nimer 1 was repeated with the exception that another inert carrier was used.

Examples 10-14. The experiment described in Example 1 was repeated with the exception that the atomic ratio between the metal elements present in the catalytic oxide was changed.

The results are shown in Table. five.

The results obtained in Examples 1-14 show that the reaction can be carried out in a wide range of conditions without reducing the yield of acrylic acid.

The results are shown in Table. 3

Table 3

Received

the results are shown in Table. four.

Table 4

Example 15. Using the same catalyst and apparatus as described in Example 1, the reaction is carried out with a gaseous mixture of composition, vol. %: 4 methacrolein, 51 air and 45 water vapor at a temperature of 340 ° C and a spatial velocity of 2000 hours. The conversion of methacrolein is 70%; the selectivity of methacrylic acid production is 75.5%; methacrylic acid yield in a single pass of 52.8%.

Subject invention

Claims (3)

1. A method for producing an unsaturated carboxylic acid by oxidizing an unsaturated aldehyde in the vapor phase in the presence of a catalyst consisting of metals of variable valence deposited on an inert carrier, followed by separation of the target product, characterized in that the catalyst is used to increase the yield of the target product containing chromium and / or tungsten and molybdenum, vanadium, copper. Table 5 taken at atomic ratio equal to check 4: check 12: 12: 2-14: 1-6. 2. A method according to claim 1, characterized in that an inert support is used for the catalyst with a specific surface area of not more than 2, with a porosity of 30-65%, in which at least 90% of the pores must have a diameter of 50 to 1500 microns. 3. Method according to paragraphs. 1 and 2, characterized in that the process is carried out at a temperature of 200-350 ° C and a pressure of 1-10 atm.