MXPA98001660A - Procedure for the elaboration of acrylic acid from acrolein by oxidation reduction reaction and use of a composition of mixed oxides as an oxidation system reduction in such reacc - Google Patents

Abstract

The present invention relates to the use of a solid composition of mixed oxides of the formula (I): 2 < -a < -14, 0.1 < -b < -6, 0 < -c < -12, 0 < -d < -6, 0 < -e < -15;, x is the amount of oxygen bound in the other elements and depends on its oxidation states, in the preparation of acrylic acid by acrolein oxidation, said solid composition reacted with acrolein according to the oxidation-reduction reaction: SOLIDOoxido + ACROLEIN - > SOLIDOreducido + ACRILIC ACID, to make an acrylic acid, a gaseous mixture of acrolein and steam is passed and, if appropriate, an inert gas, on a solid composition of the formula (I), to conduct the oxidation reaction -reduction (1) working at a temperature of 200 to 500 ° C, at a pressure of 1.01 x 104 to 1.01 x 106 Pa (0.1 to 10 atmospheres), and with a dwell time of 0.01 second to 90 seconds, in the absence of oxygen molecul

Description

PROCEDURE FOR THE ELABORATION OF ACRYLIC ACID FROM ACROLEIN BY OXIDATION REACTION-REDUCTION AND USE OF A SOLID COMPOSITION OF MIXED OXIDES AS AN OXIDATION SYSTEM- REDUCTION IN SUCH REACTION DESCRIPTIVE MEMORY The present invention relates to the preparation of acrylic acid from acrolein by oxidation according to an oxidation-reduction reaction. The invention also relates to the use of a solid composition of mixed oxides as an oxidation-reduction system for said reaction. The industrial production of acrylic acid is currently carried out by catalytic oxidation of the acrolein in the vapor phase. All attempts to improve this process have so far been related to the development of catalysts that give the highest possible conversion of acrolein and the highest possible selectivity of the desired acrylic acid. Thus, French Patent No. 2 222 349 discloses a catalyst for the preparation of acrylic acid by catalytic oxidation of acrolein vapor phase using a gas containing molecular oxygen, this catalyst including a catalytic oxide on an inert porous support, having this catalytic oxide the following metallic composition: M? L2V2-l «Z? .l-6W? -12CU? -6 being at least 2 of Be, Mg, Ca, Ba, and Sr, and always being present at least one of W and Cu. This catalyst can be prepared by adding a support (pulverized material or α-alumina, silicon carbide or similar globules) to an aqueous solution in which compounds of the various catalyst elements are dissolved, evaporating the aqueous solution to dry to deposit the catalyst elements on the support and calcining the dried product between 300 and 800 ° C. The Applicant Company has now discovered that acrylic acid can be made by acrolein gas phase oxidation in the absence of molecular oxygen, by passing a gaseous mixture of acrolein and water vapor and, if appropriate, an inert gas on a Solid composition of specific mixed oxides, which acts as an oxidation-reduction system and supplies the oxygen necessary for the reaction. The advantages of this new procedure are the following: the disadvantage of an oxidation with molecular oxygen is the over oxidation that promotes the degradation of the products formed; according to the present invention, since the operation is carried out in the absence of molecular oxygen, the formation of C0 * (carbon monoxide and carbon dioxide), degradation products, is reduced, and this allows to substantially increase the acrylic acid selectivity; the selectivity of acrylic acid remains appropriate when the degree of reduction of the solid composition increases; once it has undergone a reduction and the progressive loss of its activity, the solid composition can be easily regenerated by heating in the presence of oxygen or an oxygen-containing gas after a certain period of use; after regeneration the solid recovers its initial activity and can be used in a new reaction cycle; the separation of the steps of reducing the solid composition and its regeneration makes it possible to: increase the selectivity of the acrylic acid; e - increasing the partial pressure of acrolein, a partial portion of the acrolein supply being no longer restricted by the existence of an explosive region of mixture of acrolein plus oxygen. The subject of the present invention is therefore first of all the use of a solid composition of mixed oxides of the formula (I): Mo 12, Sn, WcCUdSi, 0? (I) in which: - a is between 2 and 14, including the limits, - b is between 0.1 and 6, including the limits, - c is between 0 and 12, including the limits, - d is between O and o, including the limits, - e is between 0 and 15, including the limits, - x is an amount of oxygen linked to the other elements and depends on their oxidation states, in the production of acrylic acid by oxidation of acrolein, said solid composition reacting on acrolein according to the oxidation-reduction reaction (1): SOLID ,, xi given + ACROLEIN- >; S0LID0r tucid + ACRYLIC ACID (1). The oxides of the various metals that form part of the mixed oxide composition of the formula (I) can be used as starting materials in the preparation of this composition, but the starting materials are not restricted to the oxides; other starting materials include: - in the case of molybdenum: ammonium molybdate and olibic acid, - in the case of vanadium: ammonium metavandate, - in the case of strontium: strontium hydroxide, carbonate or nitrate, - in the case of tungsten: ammonium tungstate and tungstic acid, in the case of copper: copper hydroxide, carbonate or nitrate, and, in general, any compounds capable of forming an oxide by calcination, namely metal salts of organic acids , metal salts of inorganic acids, complex metal compounds and organic metal compounds, and the like. The silicon source generally consists of colloidal silica. According to the specific embodiments, the solid compositions of the formula (I) can be prepared by mixing, while stirring, aqueous solutions of ammonium paratungstate, ammonium metavanadate, ammonium molybdate and copper nitrate and strontium nitrate, adding colloidal silica if appropriate, and then drying and calcining in air between 300 and 600 ° C, preferably between 350 and 500 ° C. Another subject of the present invention is a process for the preparation of acrylic acid from acrolein, a process according to which a gaseous mixture of acrolein and water vapor is passed and, if appropriate, an inert gas such as nitrogen, on a solid composition of the formula (I) defined above, to conduct the reaction-oxide reaction (1) as indicated above, working a temperature of 200 to 500 ° C, especially 250 to 450 ° C, a pressure of 1.01 x 10 * at 1.01 x 106 Pa (0.1 to 10 atmospheres), especially from 5.05 x 10 * to 5.05 x 105 Pa (0.5 atmospheres) and with a residence time of 0.01 second to 90 seconds, especially 0.1 second to 30 seconds, in the absence of molecular oxygen. The volume ratio of acrolein / water vapor in the gas phase is not critical and can vary within wide limits. During the oxidation-reduction reaction (1), the solid composition undergoes a reduction and a gradual loss of its activity. That is why, once the solid composition has changed to the reduced solid, the regeneration of said solid composition is conducted according to the reaction 2: SOLID produced + O 2 - > SOLIDOox i given (2) by heating in the presence of an excess of oxygen or of a gas containing oxygen at a temperature of 250 to 500 ° C, during the time necessary for the reoxidation of the solid composition. After regeneration, which can be carried out under conditions of temperature and pressure that are identical or different from those of the oxidation-reduction reaction, the solid composition recovers an initial activity and can be used in a new reaction cycle. . The oxidation-reduction reaction can be conducted (1) and regeneration in a two-stage device, namely a reactor and a regenerator operating simultaneously and in which the two charges of the solid composition alternate periodically; the oxidation-reduction reaction (1) and the regeneration in the same reactor can also be conducted by alternating the reaction and regeneration periods. The preparation of the acrylic acid according to the invention takes place in accordance with the stoichiometric and non-catalytic reaction. The following examples illustrate the present invention without, however, restricting its scope. Conversions, selectivities and yields are defined as follows: Number of moles of acrolein that have reacted Conversion (%) = x 100 Number of moles of acrolein introduced Number of moles of acid Selectivity (%) acrylic formed from acrylic acid = - - - - x 100 Number of moles of acrolein that have reacted Number of moles of acid Selectivity (%) acetic formed from acetic acid = x 100 Number of moles of acrolein that have reacted EXAMPLE Ka) Preparation of a Solid of the Formula M012V4.eSro.sW2.4Cu2.2Ox where x is the quantity of the amount of oxygen in loops to the other elements and which depend on their oxidation states. 3.6 g of ammonium paratungstate, 3.0 g of ammonium metavanadate and 12.4 g of ammonium heptamolybdate are introduced into 100 g of water and heated to 100 ° C. 3.0 g of copper nitrate and 0.62 g of strontium nitrate are added to 5 g of water and heated to 100 ° C. The second solution is added to the first and the resulting solution is then evaporated to dryness and then calcined for 4 hours at 400 ° C.

EXAMPLE Kb) (Comparative) Preparation of Acrylic Acid from Acrolein 50 mg of a solid prepared according to Example 1 (a) is introduced into a tubular reactor and the reactor is then sprayed with a continuous flow of 20 ml per minute of air and heated to 300 ° C. An injection of an aqueous solution of 12% by weight of acrolein, containing 1.1 x 106 moles of acrolein, is introduced onto the solid. It is converted into 97% acrolein with selectivities of acrylic acid and acetic acid of 56% and 4% respectively.

EXAMPLE 2 Preparation of Acrylic Acid from Acrolein by an Oxidation-Reduction Reaction After the treatment of Example 1 (b) the reactor was sprayed with a continuous flow of 17 ml / min of nitrogen and heated to 30 ° C. The 12% acrolein aqueous solution infection, containing 1.1 x 106 moles of acrolein, was introduced onto the solid. It became 99.15 of acrolein, with the selectivities of acrylic acid and acetic acid being 65% and 6.5% respectively.

EXAMPLE 3 After conducting the reaction of Example 2, the same solid was again subjected to eleven successive injections of acrolein under the same test conditions as in Example 2. The yield values obtained are presented in Table 1. (The injection No. 1 corresponds to Example 2).

TABLE 1 EXAMPLE 4 After the reduction treatment of Example 3, the solid is regenerated for 2 hours at 300 ° C under an air flow and then placed under a flow of nitrogen again. Twenty-four new successive injections of 12% by weight aqueous solution of acrolein, containing 1.1 x 10-6 moles of acrolein, are introduced onto the solid. The obtained yield values are presented in Table 2.

TABLE 1 Injection Conversion of Selectivity Selectivity No. acrolein (%) of acrylic acid (%) acetic acid (%)

Claims (6)

NOVELTY OF THE INVENTION CLAIMS

1. - Use of a solid mixed oxide composition of the formula (I): Moi2V.SrbWcCudSi, 0x (I) in which: a is between 2 and 14, including the limits, b is between 0.1 and 6, including the limits, c is between 0 and 12, including the limits, d is between 0 and 6, including the limits, e is between 0 and 15, including the limits, x is an amount of oxygen linked to the other elements and it depends on its oxidation state, in the production of acrylic acid by acrolein oxidation, said solid composition reacting with acrolein according to the oxidation-reduction reaction (1): SOLIDOo idado + ACROLEINASOLIDOrDUCTED + ACRYLIC ACID (1).

2. Process for the preparation of acrylic acid from acrolein, characterized in that once the acrolein and water vapor gas and, if appropriate, an inert gas are passed over a solid composition of the formula (I) as defined in claim 1, for conducting the oxidation-reduction reaction (I) as set forth in claim 1, working at a temperature of 200 to 500 ° C, at a pressure of 1.01 x 10 * a 1.01 x 106 Pa (0.1 to 10 atmospheres) and with a residence time of 0.01 second to 90 seconds in the absence of molecular oxygen.

3. Method according to claim 2, characterized in that the oxidation-reduction reaction (1) is conducted at a temperature of 250 to 450 ° C.

4. Method according to any of claims 2 and 3, characterized in that the oxidation-reduction reaction (1) is conducted at a pressure of 5.05 x 10 * to 5.05 x 105 Pa (0.5 atmospheres).

5. Method of compliance one of claims 2 to 4, characterized in that the reaction-oxide reaction (1) is conducted with a residence time of 0.1 second to 30 seconds.

6. - Method of compliance one of claims 2 to 5 characterized in that, once the solid composition has changed to the reduced state, the regeneration of said solid composition is conducted according to the reaction 2: SOLID • ducido +02 - > SOLID00 x i d ad or (2) heating in the presence of an excess of oxygen or of a gas containing oxygen at a temperature of 250 to 500 ° C, during the time necessary for the reoxidation of the solid composition. 1. - Method according to claim 6, characterized in that the oxidation-reduction reaction (1) and the regeneration are conducted in a two-stage device, namely a reactor and a regenerator operating simultaneously in which the two loads of the solid composition alternate periodically. 8. Method according to claim 6, characterized in that the oxidation-reduction reaction (1) and the regeneration in the same reactor are conducted alternating the reaction and regeneration periods.