JPS6211618B2 - - Google Patents

Description

[Detailed description of the invention]

Already taking acrolein or methacrolein,
A number of catalysts are known that are effective for oxidizing to acrylic acid or methacrylic acid, respectively. However, the yields obtained using the above catalysts for the production of methacrylic acid are low. West German Provisional Patent No. 2048620
The issue discloses catalysts containing oxides of molybdenum, phosphorus, and arsenic for the oxidation of methacrolein and acrolein to methacrylic acid and acrylic acid, respectively. US Pat. No. 3,761,516 discloses a catalyst comprising oxides of molybdenum, arsenic, and phosphorus on a support, especially Al ₂ O ₃ , with external macropores and a surface of less than 2 m ² /g. The present invention is the result of a search for more efficient and desirable catalysts for the production of methacrylic acid. by gas phase oxidation of methacrolein with molecular oxygen in the presence of the novel and useful catalysts of the present invention.
Unexpectedly high yields and selectivities to methacrylic acid are obtained. Experimental according to the invention as a catalyst in a process for the production of methacrylic acid by oxidation of methacrolein, respectively, with molecular oxygen in the presence of an oxide catalyst and optionally in the presence of water vapor in the gas phase at a reaction temperature of about 200 to about 500 °C. _{Formula : _ _ _ _} is from 0 to 10,
c is 0.01 to 5, d is 0.01 to 5, and x is the number of oxygens required to satisfy the valence states of other elements present); or As a catalyst, the empirical formula is X _a Mo ₁₂ P _c As _d O _x () (where,
, c is 0.01 to 5, d is 0.01 to 5, and x is the number of oxygens required to satisfy the valence states of other elements present). An improved method has been discovered that is characterized by the following. Efficient at relatively low temperatures. Improved yields of methacrylic acid from methacrolein, respectively, in a convenient and economical manner are provided by the surprisingly advantageous catalysts of the present invention. The exotherm of the reaction is low, so the reaction can be easily controlled. The most important aspect of the invention is the catalyst used.
The catalyst can be any catalyst represented by the empirical formula (), (). The catalyst can be prepared by many different methods described in the art, such as coprecipitation of soluble salts and calcination of the product. The catalyst of the invention has favorable limits for its composition. When using the catalyst of the empirical formula (), a is 0.001
~3 catalyst, b is 0.001~3 catalyst, b
is preferably 0. Particularly preferred are catalysts in which X is cerium, erbium or a mixture of rare earth elements consisting essentially of Ce, La, Nd, Pr. Catalysts of particular interest are those in which Y is silver or copper. When using the catalyst of the empirical formula (), a is 0.01
-3 catalysts are preferred. Particularly preferred is a catalyst in which each of the elements represented by X is separately incorporated into the catalyst. The above can be conveniently accomplished by making X independently equal to the various elements of interest. In preparing the catalyst, the various elements of the catalyst are brought together and the final product is calcined to obtain the catalyst. Many methods of mixing catalytic elements and calcining the product are known to those skilled in the art. In the broad concept of the invention:
The particular method of catalyst preparation is not critical. However, there are methods of preparing the catalyst that have been found to be preferred. One preferred method of preparation involves preparing the catalyst in an aqueous slurry or solution of molybdenum, arsenic, and/or phosphorus-containing components, adding the remaining components, evaporating the aqueous mixture, and calcining the resulting catalyst. do. Suitable molybdenum compounds that can be used to prepare the catalyst of the above formula include molybdenum trioxide, molybdophosphoric acid, molybdic acid, ammonium heptamolybdate, and the like. Suitable phosphorus compounds that can be used in the preparation of this catalyst include orthophosphoric acid, metaphosphoric acid,
Contains triphosphates, phosphorus halides or phosphorus oxyhalides. The remaining components of the catalyst can be added as oxides, acetates, formates, sulfates, nitrates, carbonates, oxyhalides, halides, and the like. Phosphoric acid, arsenic-containing compounds, molybdenum trioxide,
or ammonium heptamolybdate in water with approx.
Excellent results are obtained by refluxing for 0.5 to 3 hours. Commercially available molybic acid can be used effectively, with excellent results by adding the remaining ingredients to the above aqueous slurry, boiling to a thick paste, drying in air at 110-120°C, and calcining the resulting catalyst. is obtained. Calcination of the catalyst is typically accomplished by heating the dry catalyst components to about 200 to about 700°C. The preferred operation of the present invention is to calcinate the catalyst at 325-425°C. The reactants in the reaction of the invention are methacrolein and oxygen. Molecular oxygen is usually supplied to the reaction in the form of air, but oxygen gas can also be used. About 0.5 to 4 moles of oxygen are usually added per mole of methacrolein. The reaction temperature can vary depending on the catalyst used. Usually temperatures of about 200 to about 500°C are used;
A temperature of 370°C is preferred. The catalyst can be used alone or with a support. Suitable supports include silica, alumina, alundum, silicon carbide, boron phosphate, zirconia, titania. The catalysts can be conveniently used in fixed bed reactors using tablets, pellets, etc., or in fluidized bed reactors using catalysts having a particle size of about 300 microns or less. When using a fluidized bed reactor, the preferred catalyst is in the form of microspheroidal particles. The contact time can be as short as 1 second or as long as 20 seconds or more. Although the reaction can be carried out at normal, elevated, or reduced pressure, a pressure of about 0.5 to about 4 atmospheres absolute is preferred. Excellent results are obtained using coated catalysts consisting essentially of an inert support material having a diameter and outer surface of at least 20 microns and a continuous coating of the active catalyst on said support strongly adhered to the outer surface of said support. . This particularly coated catalyst consists of an internal carrier material having an outer surface and a coating of active catalytic material on the outer surface. These catalysts can be prepared by many different methods. The catalyst support material forms the inner core of the catalyst. It is an essentially inert carrier and can be of virtually any particle size, although diameters of 20 microns or greater are preferred. Particularly preferred in this invention for use in commercial reactors are supports that are spherical and have a diameter of about 0.2 to about 2 cm. Suitable examples of essentially inert support materials include alundum, silica, alumina, alumina-silica, silicon carbide, titania, zirconia. Among these carriers, particularly preferred are alundum, silica, alumina, and alumina-silica. The catalyst can contain essentially any proportion of support and catalytically active material. The limits of this relationship are determined only by the relative ability of the catalyst and support materials to be compatible with each other. Preferred catalysts contain from about 10 to about 100 weight percent catalytically active material, based on the weight of the support. Preparation of this coated catalyst can be accomplished by various methods. The basic method for preparing this catalyst is to partially wet the support material with liquid, then contact the support material with a powder of catalytically active material, and gently stir the mixture until the catalyst is formed. This gentle agitation is most conveniently accomplished by placing the partially filled carrier in a rotating drum or jar and adding the powdered active catalyst material. When the catalyst of the present invention is used to produce methacrylic acid,
Excellent yields are obtained in convenient reactions with small amounts of by-products. Comparative Examples A to D, Examples 1 to 29, and Reference Examples 1 to
4. Comparison of Catalysts Containing Cocatalysts of the Invention and Basic Catalysts in the Production of Methacrylic Acid A 20 c.c. fixed bed reactor consisted of 1.3 cm stainless steel tubing. The catalyst prepared as below was charged into a reactor, heated to the reaction temperature under air flow, and fed with 1/5, 7/4, 6/8, and 7 methacrolein/air/nitrogen/steam feeds for 2 to 30 minutes. It was fed onto the catalyst with an apparent contact time of 4 seconds. The reactor was operated under reaction conditions for 1-6 hours and the product was collected and analyzed. Comparative example A 25%Mo ₁₂ P ₁ As ₀ . ₅ O _x Alundum Ammonium heptamolybdate (NH ₄ ) ₆ Mo ₇ O ₂₄ .
4H ₂ O2 11.88 g (Mo 1.2 mol), 60℃ distilled water 500
ml, ammonium arsenate in 25 ml of distilled water
A solution consisting of 7.94 g of NH ₄ H ₂ AsO ₄ (0.05 mol of As) was prepared. A white precipitate is formed, which is
Heated to 100°C for 2 hours. To this mixture was added 11.53 g (0.10 mol P) of 85% phosphoric acid solution. After 0.5 hours, 5.0 g of hydrazine hydrate was added. This slurry was evaporated to a thick paste, dried in an oven at 110-120°C overnight, ground to less than 80 mesh and sieved. Take 50 g of Norton 1/8 inch SA5223 alundum balls, partially soak them with 1.8 g of water, and add 16.7 g of the active catalyst prepared above in 5 equal parts to add the catalyst powder to the alundum balls. coated. The alundum was rotated in the glass jar during and after each addition. The catalyst powder was uniformly coated on the alundum surface and the final product was dried. A hard homogeneous material was obtained consisting of an inner core of an alundum support with a continuous, strongly adherent coating of catalyst powder on the outer surface of the support.
This was then calcined at 370° C. for 1 hour in air at 40 ml/min to form an active catalyst. Examples 1-9 Various catalysts of empirical formula (1) were prepared as follows. Example 1 25% (rare earth mixture) _0.25 Mo ₁₂ P ₁ As _{0.5 O x +} 75%
Alundum. Ammonium heptamolybdate (NH ₄ ) ₆ Mo ₇ O ₂₄・
4H ₂ O 105.9 g (Mo 0.6 mol), 60℃ distilled water 700
ml, ammonium arsenate NH ₄ H ₂ As ₄ 4.0 g in 25 ml of water
(0.025 mol As) solution was prepared.
A white precipitate formed and was heated to 100° C. for about 0.5 hours. Calculate CeO ₂ 48 as an oxide in this mixture
%, La ₂ O ₃ 33%, Nd ₂ O ₃ 13%, Pr ₆ O ₁ 4.5%, other rare earth elements 1.5% Molly Coporated Rare Earth Chloride Mixture (Manufacturing Code No. 470)
4.4g was added. 85% phosphoric acid in this solution
5.8 g (P0.05 mol) of H ₃ PO ₄ was added. After 0.5 hours, 2.5 g of hydrazine hydrate was added.
Evaporate this slurry to a thick paste, 110-120
It was dried in an oven at ℃ overnight, ground to less than 80 mesh size, and sieved. Next, add this catalyst to 1/8 inch
Coated on SA5223 Alundum balls at 25% active catalyst level. Calcination was carried out in the same manner as in Comparative Example A. Examples 2-7 Catalyst Preparation 25% X _a Y _b Mo ₁₂ P ₁ As _{0.5 O x} +75% Alundum. Various catalysts of the invention were prepared. A catalyst was prepared according to the procedure of Example 1 using 105.9 g of ammonium molybdate, 700 ml of distilled water at 60 DEG C., and a solution of 4.0 g of ammonium arsenate in 25 ml of water. X and/or Y immediately before adding 5.8 g of 85% phosphoric acid and 2.5 g of hydrazine hydrate.
A catalyst component represented by was added. The following compounds and amounts were used in the preparation of this catalyst.

【table】

[Table] Example 8 25% (rare earth mixture) _0.25 Cu _0.5 Mo ₁₂ P _{1 As 0.5 O x +}
75% alundum This catalyst was prepared in the same manner as in Example 1, but
However, ammonium heptamolybdate 34.25g, ammonium arsenate 1.28g, rare earth chloride mixture 1.43g
g, copper acetate 0.161 g, 85% phosphoric acid 1.88 g, and hydrazine hydrate 0.8 g. Example 9 25% (rare earth mixture) _0.25 Ag _0.1 Mo _{12 P 1 As 0.5 O x}
+75% Alundum This catalyst was prepared in the same manner as in Example 8, but
However, 0.269 g of silver acetate was used. Comparative Examples B and C and Examples 10 to 20 Table 1 shows the results of an experiment in which methacrylic acid was produced using the catalyst of the experimental formula (1) for the oxidation of methacrolein. The following definitions were used to measure carbon atoms in feeds and products. One-pass yield % = Number of moles of methacrylic acid recovered/Number of moles of methacrolein in the feed x 100 Total conversion rate = Number of moles of methacrolein reacted/Number of moles of methacrolein in the feed x 100 Selectivity = One-pass yield Rate/total conversion rate x 100

【table】

[Table] Examples 21 to 24 and Reference Examples 1 and 2 Various catalysts of the experimental formula () were prepared as follows. Reference example 1 ₂₅ %Ag _0.25 Mo ₁₂ P ₁ As _{0.5 O x +} 75% Alundum Ammonium heptamolybdate (NH ₄ ) ₆ Mo ₇ O ₂₄・
4H ₂ O 105.9 g (Mo 0.6 mol), 60℃ distilled water 700
ml, ammonium arsenate NH ₄ H ₂ AsO ₄ 4.0 in 25 ml of water
A solution of 0.025 mol of As was prepared. A white precipitate formed and was heated to 100° C. for about 0.5 hours. Add 2.08 g of silver acetate (Ag0.0125
mol) and then 5.8 g of 85% phosphoric acid solution.
(P0.05 mol) was added. After 0.5 hours, 2.5 g of hydrazine hydrate was added. This slurry was evaporated to a thick paste and dried in an oven at 110-120℃ overnight.
It was crushed and sieved to a size of 80 mesh or less. 25% of this catalyst into 1/8 inch SA5223 Alundum balls
Coated with active catalyst level. Calcination was the same as Comparative Example A. Example 21 25% Au _0.05 Cd _{0.2 Mo 12 P 1.0 As 0.5} O _x +75% Alundum This catalyst was prepared in the _same manner as in Reference _Example 1, but
However, 150ml of water, ammonium molybdate 34.25
g, ammonium arsenate 1.28g, cadmium acetate
0.862 g, gold chloride 0.318 g, 85% phosphoric acid 1.86 g, and hydrazine hydrate 0.8 g. Example 22 25% Ru ₀ . ₂ Mo ₁₂ P ₁ As ₀ . ₅ O _x +75% Alundum This catalyst was prepared in the same manner as in Reference Example 1, but
However, water 500ml, ammonium molybdate 70.6
g, ammonium arsenate 2.64 g, ruthenium chloride
RuCl ₃・3H ₂ O 1.74 g (Ru 0.006 mol), phosphoric acid 3.84
g, and 1.6 g of hydrazine hydrate were used. Examples 23, 24 and Reference Example 2 Preparation of Catalyst 25% X _a Y _b Mo ₁₂ P ₁ As _0.5 O _x +75% Alundum Various catalysts _of the present invention were prepared. Ammonium molybdate 105.9g, 60℃ distilled water 700ml, water 25
Using a solution of 4.0 g of ammonium arsenate in ml,
This catalyst was prepared according to the procedure of Reference Example 1. Catalyst components designated X and/or Y were added immediately prior to the addition of 5.8 g of 85% phosphoric acid solution and 2.5 g of hydrazine hydrate. The following compounds and amounts were used in the preparation of this catalyst.

[Table] Comparative Examples B to D, Examples 25 to 29, and Reference Example 3,
4 Table 3 shows the experimental results of producing methacrylic acid using the catalyst of the empirical formula () for the oxidation of methacrolein. The same definitions as above were used for the measurement of carbon atoms in the feed and product.

【table】

Claims (1)

[Claims] 1 The catalyst has the empirical formula X _a Y _b Mo ₁₂ P _c As _d O _x (where X is a rare earth element or a mixture thereof, Y is at least one of Ag and Cu, a is 0.001-10, b is 0-10, c is 0.01-5, d is 0.01-5,
A catalyst for methacrolein oxidation, where x is the number of oxygens required to satisfy the valence states of other elements present. 2 X is cerium, erbium, or Ce,
The catalyst according to claim 1, which is a mixture of rare earth elements consisting essentially of La, Nd, and Pr. 3. The catalyst according to claim 1, wherein X is a mixture of rare earth elements consisting essentially of Ce, La, Nd, and Pr. 4. The catalyst according to claim 1, wherein X is cerium. 5. The catalyst according to claim 1, wherein X is erbium. 6. The catalyst according to claim 1, wherein Y is silver. 7. The catalyst according to claim 1, wherein Y is copper. 8. The catalyst according to claim 1, wherein b is 0. 9. The catalyst according to claim 1, wherein a is 0.001 to 3. 10 Claim 1 in which b is 0.001 to 3
Catalysts as described in section. 11. The catalyst according to claim 1 coated on an inert carrier. 12. The catalyst of claim 11 consisting essentially of an inert support material having a diameter and outer surface of at least 20 microns and a continuous coating of the active catalyst strongly adhered to the outer surface of the support. 13. The catalyst of claim 12, wherein the active catalyst is about 10-100% by weight of the inert support. 14 The carrier is silica, alumina, alundum, alumina-silica, silicon carbide, titania,
A catalyst according to claim 12 selected from the group consisting of zirconia. 15. The catalyst according to claim 12, wherein the inert carrier has a particle size of 0.2 to 2 cm. 16. The catalyst of claim 1, wherein the oxidation of methacrolein is carried out with molecular oxygen in the gas phase at a reaction temperature of from about 200 to about 500° C. in the presence of a catalyst and optionally in the presence of water vapor. . 17 The catalyst has an empirical formula: X _a Mo ₁₂ P _c As _{d O}
methacrolein oxidation represented by Catalyst for use. 18 Claim 1 in which a is 0.001 to 3
Catalyst according to item 7. 19 Claim 17 in which x is rhodium
Catalysts as described in section. 20 Claim 1 in which X is ruthenium
Catalyst according to item 7. 21. The catalyst according to claim 17, wherein X is gold. 22. The catalyst according to claim 17 coated on an inert carrier. 23 consisting essentially of an inert support material having a diameter and outer surface of at least 20 microns and a continuous coating of the active catalyst strongly adhered to the outer surface of said support, provided that the support is partially impregnated with water; 23. A catalyst according to claim 22, wherein the coated catalyst is prepared by rolling a moistened support in the active catalyst powder. 24 The active catalyst is about 10 to about 100% of the inert support.
24. The catalyst of claim 23, which is % by weight. 25 The carrier is silica, alumina, alundum, alumina-silica, silicon carbide, titania,
A catalyst according to claim 23 selected from the group consisting of zirconia. 26. The catalyst according to claim 23, wherein the inert carrier has a particle size of 0.2 to 2 cm. 27. The catalyst of claim 17, wherein the oxidation of methacrolein is carried out with molecular oxygen, in each case in the gas phase at a reaction temperature of about 200 to about 500°C, optionally in the presence of water vapor.