CS200229B2 - Process for preparing acrylic or methacrylic acid - Google Patents

Description

The invention relates to a process for the preparation of acrylic or methacrylic acid by oxidation of acrolein or methacrolein with molecular oxygen.

Numerous active catalysts are known for the oxidation of acrolein or methacrolein to acrylic or methacrylic acid. However, yields obtained using methacrylic acid catalysts are low. Germany Patent No. 2,048,620 protects catalysts,

.5 containing molybdenum, phosphorus and arsenic oxides used in the oxidation of methacrolein and acrolein to methacrylic and acrylic acids. U.S. Pat. No. 3,761,516 protects catalysts containing molybdenum, arsenic and phosphorus oxides on a support, especially alumina, having external macropores and a surface area not greater than 2 m @ 2 / g.

The invention is the result of research into more effective and desirable catalysts for the production of acrylic and methacrylic acids. Unexpectedly higher yields and selectivities with respect to acrylic and methacrylic acids are achieved with acrolein and methacrolein vapor phase oxidation with molecular oxygen in the presence of the novel and useful catalysts of the invention.

The invention therefore relates to a process for the preparation of acrylic or methacrylic acid by oxidation of acrolein or methacrolein with molecular oxygen in the vapor phase at a reaction temperature of 200 to 500 ° C in the presence of an oxide catalyst and optionally on an inert support and optionally in the presence of steam. using a catalyst of formula I

X _{a and} X b ^{M p} 12 ° C ^and the SDO>

where it means

X at least one element selected from the group consisting of uranium, titanium, niobium, rhenium, lead,

In zinc and gallium,

T at least one element selected from the group consisting of copper, rare earth element, silver, tantalum, indium, thorium, cadmium, thalium, alkaline earth metal, chlorine, nickel, aluminum, germanium and ammonium, and 0.001-10 b 0-10, c0 1 to 5, d 0.01 to 5, x the number of oxygen atoms required to saturate the valences of the other elements present, optionally in the form of a continuous coating on an inert support having a particle size of at least 20 microns, the active catalyst of the formula I being supported %, in an amount of 10 to 100% by weight, based on the weight of the carrier.

Preferred catalysts of the invention provide surprisingly improved yields of acrylic or methacrylic acid from acrolein or methacrolein in an efficient, easy and economical process at a relatively low temperature. The exothermic nature of the reaction is low so that the reaction can be easily controlled.

The most important aspect of the process of the invention is the catalyst used. Any catalyst characterized by formula (I) can be used as the catalyst. Catalysts can be prepared by a number of methods known in the art, such as simultaneous precipitation of soluble salts and calcination of the resulting product. The catalysts according to the invention have advantageous proportions in their composition.

Particularly preferred are catalysts in which a is 0.001 to 3, furthermore catalysts of formula I in which b is 0.001 to 3 or zero. Particularly preferred are catalysts of formula I wherein each of the elements marked with X is introduced separately into the catalyst. This is conveniently achieved by introducing X independently of the various elements. Catalysts of particular interest are those in which Y is at least one element selected from the group consisting of a rare earth element, aluminum, silver and copper.

In preparing the catalyst, the various catalyst elements are combined and the final product is calcined to obtain the catalyst. Numerous methods are known to those skilled in the art for combining catalyst forming elements and calcining the resulting product. In the process of the invention, it is not critical which process is used to prepare the catalyst.

However, some processes are particularly advantageous for preparing the catalyst. One preferred method comprises preparing a catalyst in the form of an aqueous suspension or aqueous solution of molybdenum, arsenic and / or phosphorus containing compounds and adding the remaining component, evaporating the aqueous mixture and calcining the resulting catalyst. Suitable molybdenum compounds which may be used in the preparation of the catalyst of the present invention include molybdenum oxide, phosphomolybdic acid, molybdic acid, ammonium heptamolybdate and the like. Suitable phosphorus compounds which may be used in the preparation of the catalyst of the invention include orthophosphoric acid, metaphosphoric acid, triphosphoric acid, and phosphorus halides or oxyhalides. The remaining components of the catalyst can be added in the form of oxides, acetates, formates, sulfates, nitrates, carbonates, oxyhalides or halides or in the form of similar compounds.

Excellent results are obtained by refluxing phosphoric acid, an arsenic-containing compound, molybdenum trioxide or ammonium heptamolybdate in water for half an hour to three hours, but commercial phosphomolybdic acid may also be used effectively; adding the remaining components to the aqueous suspension and boiling to a thick paste, drying at 110 to 120 ° C in air, and calcining the resulting catalyst.

Catalyst calcination is conveniently accomplished by heating the dry catalyst to 200

3, 200229-700 ° C. According to the invention, a process is preferred wherein the catalyst is calibrated at a temperature of 325 to 425 ° C.

The reactants in the process of the invention are acrolein or methacreolein and oxygen. As a rule, the molecular oxygen is supplied to the reaction mixture in the form of air, but oxygen can also be used. Normally 0.5 to 4 moles of oxygen are added per mole of methacrolein.

The reaction temperature may vary depending on the catalyst used. Normally, the process is carried out at a temperature of 200 to 500 ° C, preferably 250 to 370 ° C.

The catalyst may be used alone or on a support. Suitable carriers include silica, alumina, alundum (alumina-based product), silicon carbide, boron phosphate, zirconia, and titanium dioxide. The catalysts are typically used in a solid-bed reactor in the form of tablets, pellets or the like, or in a fluidized bed reactor in the form of particles smaller than about 300 microns. If a fluidized-bed catalyst is used, the catalyst is preferably in the form of microspheres. The contact time can be a fraction of a second or up to 20 seconds or even longer. The reaction can be carried out at atmospheric pressure, at a pressure above atmospheric pressure and at a pressure below atmospheric pressure. Preferably, the reaction is carried out at an absolute pressure of 0.05 to 0.4 MPa,

Excellent results are obtained by using a coated catalyst consisting essentially of an inert support material having a diameter of at least 20 microns, an outer surface and a continuous coating of said active catalyst on an inert support strongly adhering to the outer surface of the support.

A particular coated catalyst consists of an inner support material having an outer surface and a coating of active catalyst material on the outer surface. These catalysts can be prepared in various ways.

The catalyst support material forms the inner core of the catalyst. It is a substantially inert carrier which may have substantially any particle size, but a shape with a diameter greater than 20 microns is preferred. Particularly preferred according to the invention for the process reactors are carriers which are spherical and have a diameter of about 0.2 cm to about 2 cm. Suitable examples of such inert carriers include alundum (alumina product), silica, alumina, alumina, silicon carbide, titanium dioxide, and zirconia. Of these carriers, alundum, silica, alumina and alumina-silica are particularly preferred.

The catalysts may contain substantially any proportion of support and catalytically active material. The limit of this ratio is determined only by the mutual adaptability of the catalyst and the support. Preferred catalysts contain 10 to about 100% by weight of the catalytically active substance, based on the weight of the support.

Various methods can be used to prepare these coated catalysts. The basic method of preparing these catalysts is to partially wet the carrier with a liquid and then contact the carrier with a powder of a catalytically active material; the mixture is then stirred until the catalyst is formed. Slightly agitated: most effectively achieved by introducing the partially wetted carrier into the rotating drum. into a rotating vessel and adding powder of the active catalyst material.

By using the catalyst of the invention according to the invention for the preparation of acrylic or methacrylic acid, excellent results are obtained in a convenient manner and with a small amount of by-products. In the following example, catalysts containing the promoters of the invention are compared with the basic catalysts used in the preparation of methacrylic acid.

The 20 ml solid-bed reactor used is constructed from a 1.3-mm stainless steel tube. The catalyst is prepared as described, brought to the reaction temperature with air flow, and a 1: 5.7: 4.6: 8.7 mixture of methacrolein, air, nitrogen and steam is passed through the catalyst at an apparent contact time of 2 to 5. 4 seconds. The reactor is operated under reaction conditions for 1 to 6 hours and the product collected and analyzed.

Comparative Example A 25% iíoi2 ^p 0,50x 1 ^{As +} 75% Alundum

Prepare a solution containing 211.86 g of ammonium heptamolybdate (1 H 2 gMoyCl 4 4 H 2 O (1.2 mol molybdenum), 500 ml distilled water at 60 ° C and 7.94 g ammonium arsenate NH 4 H 2 ASO 4 (0.05 mol arsenic) in of the solution in 25 ml of distilled water, and the white precipitate is heated at 100 DEG C. for about two hours, to which 11.53 & 85% phosphoric acid solution (0.10 moles of phosphorus) are added. 5.0 g of hydrazine hydrate The suspension is evaporated to a thick paste, dried overnight in an oven at 110 to 120 ° C, grinded and sieved to a particle size of less than 80 mesh, coated with alunda beads (Norton SA 5 223) 0.317 cm diameter by 50 g of alunda partially wetted with 1.8 g of water and 16.7 g of active catalyst prepared as described above are added in five equal portions. Alunda surface The product is dried uniformly and the final product is dried to give a hard, uniform material consisting of an inner core of the alundic support and a continuous strongly adhering coating of active catalyst powder on the outside of the support. The material is then calcined for one hour at 370 ° C in an air flow of 40 ml / min to form an active catalyst.

Example 1% Uo, 25 ^! ) 12 ^{Io I} 'l ^AS 5 ⁰ x ⁺ 75% Alundum

Prepare a solution containing 105,9 g of ammonium heptamolybdate (ΝΗ4 ςΜογΙ4 .4 H2O (0,6 mol molybdenum), 700 ml distilled water at 60 ° C and 4,0 g ammonium arsenate NH4H2ASO4 (0,025 mol arsenic) as a solution in 25 ml of water, the white precipitate formed is heated at 100 DEG C. for half an hour, to which 5.3 g of uranyl acetate (0.0125 moles of uranium) is added, followed by 5.8 g of 85% phosphoric acid solution (0). 2.5 g of hydrazine hydrate are added over half an hour, the suspension is evaporated to a thick paste, dried in an oven overnight at 110 DEG-120 DEG C., milled and sieved to a particle size of less than 80 mesh. Alunda SA 5 223 spheres having a diameter of 0.317 cm were coated with the powder to contain 25% of the active ingredient, calcining as described in Comparative Example A.

Example 2% Τ1θ _ι 2ΐ4ο, 2Ϊ ^> 1 ^Α3 0.5θχ ⁺ 75% alundum

The catalyst was prepared in the same manner as described in Example 1 except that 7.72 g of 20% titanium tetrachloride solution and hydrazine hydrate were not used in the preparation of the catalyst.

Example 1 β d 3% (rare earth element mix) θ ^ ΤΙο, ιΜο ^ ΡιΑβο, ίΟχ ⁺ 75% alundum

The catalyst was prepared in the same manner as described in Example 1 except that 3.54 g of a mixture of rare earth chlorides, 0.5 g of hydrazine hydrate and 3.85 g of a 20% titanium tetrachloride solution were used.

Examples 4 to 19

Catalyst preparation 25% of the formula ^{X and} b ^Mo 12 ^P 0.5 ^As t °, x ⁺ 75% Alundum

Various catalysts of the invention were prepared as described in Example 1 using 105.9 g of ammonium molybdate, 700 ml of distilled water at 60 ° C and 4.0 g of ammonium arsenate as a solution in 25 ml of water. Catalyst components denoted by X and / or Y are added immediately prior to the addition of 5.8 g of 85% phosphoric acid and 2.5 g of hydrazine hydrate are added in all formulations except for Examples 8, 10, 12 and 18, where hydrazine hydrate does not add; in Example 4, 1.0 g of hydrazine is added. The following components are used in the indicated amounts for the preparation of the catalysts:

Example Element Compound Quantity (g) 4 ^Mb 0,25 niobium chloride 3.37 5 ^pb 0.25 lead acetate 4.75 6 ^Zn 0.25 zinc acetate 2.75 7 ^Re 0.25 rheniums e skvi oxi d 3.03 8 ^A 0,1 0.1 ^Ti 0.2 20% chloride solution titanium silver acetate 7.72 0.8 9 ^A «0.1 ^Zn 0.2 zinc acetate '2.19 silver acetate 0.8 10 ^Nb 0.05 ^Ti 0.2 niobium chloride 20% titanium tetrachloride solution 0.67 7.72 11 ^Re 0.1 ^Cu 0.25 rheniumseskvioxid copper acetate 1,21 2,48 ' 12 ^{Ti 0.15 Zn} 0.1 20% titanium tetrachloride zinc acetate 5.78 1.1 13 Zng, i (rare earth mixture) _n zinc acetate chloride mixture 1, 09 rare earths 3.54 14 ^Ti 0.05 ^Cu 0.05 20% titanium tetrachloride 1.92 (mixture of rare earth elements) _{0) 2} copper acetate a mixture of rare earth chlorides 3.54 15 Dec ^Zn 0.05 ^Cu 0.05 zinc acetate 0.55 (rare earth mix) 0.3 copper (II) acetate mixture of chloride elements 0.50 rare earths 3.54. 16 ^Ca 0.25 gallium oxide 1.1

continued table

Example Element Compound Quantity (g) 17 ^Zn 0.2 ^A1 0.05 ^Cu 0.05 zinc acetate aluminum chloride copper acetate 2.19 0.6 0.50 18 Tíq ₂ rare 20% titanium tetrachloride, 7.7 earth _{0 | 05} Cu _{0 (05} a mixture of rare earth elements copper (II) acetate 0.9 0.50 19 Dec rare earthQ ₍ , Pbg, ₂ lead acetate a mixture of rare earth elements 3.8 1.77

Example 20% Mo, ₂ P, Asq, 5 ^ 6q ₍ 25 ^and Sat, 05θχ ⁺ 75% alundum)

The catalyst was prepared in the same manner as described in Example 1 except that 34.25 g of ammonium molybdate, 150 ml of water, i, 28 g of ammonium arsenate, 0.537 g of niobium chloride, 0.134 g of silver azetate, 1.86 g were used. % of phosphoric acid and 0.8 g of hydrazine hydrate.

Example 2,% Mo, gP, AsQ, 5 ^ 0.25 ^ 0.1¾ + 75% alundum

The catalyst was prepared in the same manner as described in Example 4, except that 0.322 g of copper acetate was used to prepare niobium chloride.

Example 22% ZnO, ^Al 2 O _l O 08 ^Cu, 05 ^Mo 12 ^P 1.32 ^As 0.5 ° x + 75% Alundum

The catalyst was prepared in the same manner as described in Example 37, except that 0.96 g of aluminum chloride hydrate and 7.6 g of 85% phosphoric acid were used.

Example 23% ^Re 0.01 ^Al 0.091 ^Cu 0.05 ^Mo 12 ^P 1.32 ^As 0.5 ° x ⁺ 75% alundum

The catalyst was prepared in the same manner as described in Example 22, except that 1.1 g of aluminum chloride hydrate and 1.21 g of Rh3O4 were used.

«Γ

Comparative Example B to D and Example 24 to 47

The results of the tests on the use of catalysts of the formula I in the oxidation of methacrolein to methacrylic acid are given in Table 2. The number of carbon atoms in the raw material and in the mole product of the obtained methacrylic acid is assessed according to the following equations:

% yield per pass moles of metacrolein introduced x 100 moles of reacted methacrolein total conversion = - x) 00 moles of metacrolein introduced per pass pass selectivity = - x 100 total conversion

The catalysts of the formula I can be used as described above for preparing acrylic acid from acrolein. Table 2

The activity of the catalysts of the formula I containing the promoters according to the invention in comparison with the basic catalyst in the preparation of methacrylic acid

Re- action Results% Meta- Octová Celko- Selek- Example Catalyst pulse- kry- kyše- competitiveness lota lová lina version Noc: 2 ° C kyše- lina

Composition

(B) 25 Mo, 2 ^ * 1 ^As 0.5% ⁺ 75% alundum 326 19.6 0.5 26.0 75.0 C 25% Mo, gPjAso4Ojj + 75% alundum 350 43.0 1.9 56.0 76.0 D 25% Mo, 2P, Asq + 75% alundum 376 57.0 4.8 83.0 68.0 24 25% Uo, 25 ^Mo , 2 ^{µl As} 0.5 ° x ⁺ + 75% alundum 329 61.0 4.8 83.0 73.6 25 25% TIQ ° 2 ^ 12 ^ 1 ^ ³ 0,5θχ ⁺ 75% Alundum 315 66.5 5.1 84.0 79.0 26 ⁺ / 25% from _{0) 2} Ti _0i , Mo, 2P, As ₀₎ 50 _x + + 75% alundum 356 55.2 7.2 85.5 64.9 27 Mar: 25% Nbo, 25 ^Mo 1 2 ^ * 1 Asq, 5θ ⁺ + 75% Alundum · 350 50.0 2.2 59.0 84.0 28 25% NbQ, 25 (40) 2- (14-80.50 _x + _z + 75% alundum) 376 60.0 2.4 73.0 81, 0 29 25% Pbg ₍ 25M0.2P, Asq ^ 0 _χ + + 75% alundum) 343 65.7 2.8 79.0 83.0 30 25% 0η0 ₍ 25 ^Μο ^2 ^ 1 ^ ³ Ο, 5θ ⁺ + 75% alundum 343 65.3 6.2 90.0 72.0 31 25% ^ ^β 0.25 ^ ° 12 ^ ΐΑ ³ 0.5θχ ⁺ + 75% alundum 358 63.1 3.7 80.0 78.0 32 25% Ag _{0 (} , Ti _{0 (} 2Mo, 2P, As _0> 50 _x + +, 75% alundum) 334 54.8 6.0 77.7 70.6 33 25% Mo AgQjZno ^ ^ ^ lAso.OS ^{1 +} 75% Alundum 346 61.3 4.4 79.8 76.7

continuation of Table 2

Example Catalyst Re- action pulse- lota Noc: 2 ° C IN Meta- kry- lové kyse- lina Acetic acid d k y Total conversion « Selek- tivita 34 25% AgQ _f 05 ^Nb 0.25 ^Mo 12 ^{µl Ab} 0.5 ° x ⁺ + 75% alundum 374. 59.3 5.2 83.1 71.4 35 25% ^T and _0L2 ^Nb 0.05 ^Mo 12 ^P 1 ^As 0.5 ° x + 75% Alundum 344 60.8 6.2 84.8 71, 7 36 25% Re _{0) 1} Cu _0i 25 Mo ₁₂ P, Aso ₍₅ O _x + + 75% alundum) 342 73.4 3.4 88.8 82.6 37 25 * Thio, 15 ^Zn 0 (1 ^M ° 12 ^P 1 ^As 0.5 ° x ⁺ + 75% alundum) 347 65.9 4.9 85.1 77.0 38 25% ^v - ^z -0.2 ^Zn 0.1 ^Mo t 2 ^P , ^As 0.5 ° x + + 75% alundum 321 6,, 3 4.0 76.3 80.3 39 25% w / w + 75% alundum 332 62.0 5.0 84.8 73.1 40 ^25% - ^z · _Ø 2 ^ nQ ₍₀₅ ^u ^ 0 ^ O5 ^P 1 ° 12 ®0,5θχ ^{A +} 75% Alundum 330 67.2 4.6 84.5 79.5 41 25% Gbq 25 ^Mo 12 ^{µl As} 0.5 ° x ⁺ + 75% alundum 370 62.8 4.9 84.5 74.3 42 25% Zn ₀ , 2 ^and 1o, 05 ^Cu 0.05 ^Mo 12 ^p 1 ^As 0.5 ° x ⁺ + 75% alundum 327 75.3 4.1 91, 8 82.0 43 25% of ^τ 1 · 0,2 · ^ν · ^ι 0.05 0.05 ^{Οα Μο p} 1 2 1 ^As 0.5 ° x ⁺ 75% Alundum 328 66,9- 5.1 89.1 75.1 44 ₀ to 25% Nb, 25Cuo 1 ^Mo 12 O ^p l ^As, x ⁺ 5 ° to + 75% Alundum 346 66.3 7.5 89.8 73.9 45 25% in _0.1 ^Pb 0.2 ^Mo 12 ^{P As} 0.5 ° x + + 75% .alundum 342 59.5 4.8 79.6 74.4 46 25% Zno _{) 2} * lo, 08 ^Cu 0.05 ^Mo 12 ^p 1.32 ^Ab 0.5 ° x ⁺ + 75% alundum 344 76.1 2.6 90.6 83.8 47 25% Ke _{0 | 1} Alo, 091 ^Cu O, 05 “ ⁰ 12 ^p 1.32 ^As 0.5 ° x ⁺ + 75% alundum 343 69.0 4.1 83.2 82.8

Note: ⁺ / vz stands for rare earths

Claims (9)

SUBJECT OF THE INVENTION A process for the preparation of acrylic or methacrylic acid by oxidation of acrolein or methacrolein with molecular oxygen in the vapor phase at a reaction temperature of 200 to 500 ° C in the presence of a catalyst, optionally on an inert support and optionally in the presence of steam. Xg = Mo ^ PeAsf10Jc (I), where is X at least one element selected from the group consisting of uranium, titanium, niobium, rhenium, lead, zinc and gallium, Y at least one element selected from the group consisting of copper, rare earth element, silver, tantalum, indium, thorium, cadmium, thalium, alkaline earth metal, chlorine, nickel, aluminum, germanium and ammonium, and 0.001-10, b 0-10 0.1 to 5, d 0.01 to 5, x the number of oxygen atoms required to saturate the valences of the other elements present, optionally in the form of a continuous coating on an inert support having a particle size of at least 20 microns, the active catalyst of the formula It is present on the carrier in an amount of 10 to 100% by weight, based on the weight of the carrier. 2. A process according to claim 1, wherein X, Y, b, c, d and x are as defined in 1 and a is 0.001 to 3. 3. A process according to claim 1, wherein X, Y, a, c, d, x are as defined in 1 and b is 0.001 to 3 or zero. 4. A process according to claim 1, wherein Y, a, b, c, d, x are as defined in 1 and X is one element selected from the group consisting of uranium, titanium, lead, niobium, rhenium, zinc and gallium. 5. A process according to claim 1, wherein Y, a, b, c, d, x are as defined in 1 and X is titanium and niobium. 6. A process according to claim 1, wherein X is titanium and zinc and Y, a, b, c, d, x are as defined in point 1. 7. A process according to claim 1, wherein X, a, b, c, d, x are as defined in 1 and Y is at least one member of the group consisting of a rare earth element. , aluminum and silver. • 8. A process according to claim 1, wherein X is rhenium and Y is copper and a, b, c, d, x are as defined in 1. 9. A method according to claim 1, wherein a carrier having a particle size of 0.2 to 2.0 cm is used.