GB1560238A - Production of metharcrylic and acrylick acids and their esters - Google Patents

Description

(54) IMPROVEMENTS IN AND RELATING TO THE PRODUCTION OF METHACRYLIC AND ACRYLIC ACIDS AND THEIR ESTERS (71) We, NIPPON KAYAKU KABUSHIKI KAISHA, a Japanese Company of New Kaijo Building, 2= 1-Chome Marunouchi, Chiyoda-ku, Tokyo, Japan do hereby declare the invention, for which we pray that a Patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a process for producing methacrylic acid and a methacrylate or acrylic acid and an acrylate at the same time.

More particularly, this invention relates to a process for simultaneously producing methacrylic acid and a methacrylate or acrylic acid and an acrylate by reacting methacrolein or acrolein with an aliphatic. alcohol and molecular oxygen in the vapor phase by using a catalyst comprising (1) palladium, (2) phosphorus, (3) antimony, (4) X and (5) oxygen wherein X denotes at least one element selected from the group consisting of potassium, sodium, lithium, rubidium, cerium, beryllium, lead, magnesium, calcium, strontium, zinc, barium, thorium, bismuth, chromium, iron, nickel, cobalt, vanadium, manganese, tin, uranium and rhenium.

The process of the invention may further comprise supplying into the reaction system a phosphoric acid or a phosphorus compound capable of forming a phosphoric acid through a chemical change during the reaction.

For the synthesis of methacrylic acid by oxidizing methacrolein in a vapor phase a number of catalysts have hitherto been proposed.

Almost all of these catalysts, however, have low activities. Further, if the reaction is carried out at an elevated temperature in order to increase the conversion, large amounts of undesirable by-products such as carbon monoxide, carbon dioxide, acetic acid etc. are produced so that the per-pass yield of methacrylic acid is very low.

The catalysts as disclosed in the Japanese Patent Laid-Open Publication Nos.

67216/1973 and 61416/1973, which are improved in their catalytic activity and selectivity, comprise phosphomolybdic acid or its salts as the main ingredient.

Phosphomolybdic acid-based catalysts have a disadvantage that the catalyst lifetime is short. Once they lose activity, it cannot be restored by means of a simple treatment such as re-calcination, for example. When the temperature of reaction or calcination exceeds 450"C, they are abruptly degraded in catalytic activity. Thus, they are thermally unstable and they are not always available for commercial use.

Further, conventional phosphomolybdic acid-based catalysts offer a notably short catalytic lifetime when the reaction is carried out at a particularly high space velocity.

Japanese Patent Laid-Open Publication No. 30,826/1975 discloses a process for producing methyl methacrylate which comprises subjecting a gas mixture of methacrolein, methanol, oxygen, steam and nitrogen to the reaction in the vapor phase in the presence of a molybdenum-vanadium-tungsten series catalyst. The process is far from commercially satisfactory because the yield of methyl methacrylate is very low.

Another disclosure relating to a catalyst containing palladium phosphorus and oxygen is described in Japanese Patent Laid-Open Publication No. 37,719/1975.

Methacrylic acid is prepared by oxidizing methacrolein with molecular oxygen in the presence of the above catalyst. The destined product, methacrylic acid is produced in higher yield and selectivity, while a comparatively large amount of steam is required. The larger the feed, the larger the equipment, which is undesirable on an industrial scale and economically disadvantageous. Since the, process of the above application is only directed to the preparation of methacrylic acid, it is, of course, impossible to prepare an ester at the same time.

The inventors made precise investigations to obviate the above described drawbacks and have achieved the present invention.

According to the present invention, methacrolein or acrolein is susceptible to oxidation at low temperature such as 1600 to 3500C and methacrylic acid and a methacrylate or acrylic acid and an acrylate are produced in high yields at the same time. Further the formation of by-products such as acetic acid, carbon monoxide and carbon dioxide owing to degradation is well suppressed. The amount of steam to be fed during the reaction may be very small, which is one of the important characteristics of the invention. In addition the catalyst according to the present invention is thermally stable and therefore has a substantially longer service life, particularly even when the reaction is carried out at high space velocities.

The process of the invention is not only economically advantageous, but also industrially epoch-making.

The catalyst to be used in the present invention comprises (1) palladium, (2) phosphorus, (3) antimony, (4) X and (5) oxygen wherein X denotes at least one element selected from the group consisting of potassium, sodium, lithium, rubidium, cerium, beryllium, lead, magnesium, calcium, strontium, zinc, barium, thorium, bismuth, chromium, iron, nickel, cobalt, vanadium, manganese, tin, uranium, and rhenium and has a long service life which is significantly superior to those of the prior phosphomolybdic acid-based catalysts.

It has surprisingly been found that the catalyst is stable at elevated temperatures, for example, at 6000C.

However, this catalyst as such is not completely satisfactory, because a part of the phosphorus which is one of the essential components of the catalyst, though in a very small amount, leaves the catalyst system during the reaction. Consequently, the semipermanent life required for commerical catalysts can not be attained.

We have found that when the reaction is carried out in the presence of the catalyst, the catalyst can be stabilized and its service life can further be prolonged by continuously or intermittently supplementing phosphorus in an appropriate amount corresponding to that of the phosphorus which leaves the catalyst system.

The process of the present invention is epoch-making and of great value for commercial use since methacrylic acid and a methacrylate or acrylic acid and an acrylate can be selectively produced in high yields for long periods of time.

The term "a phosphoric acid or a phosphorus compound capable of forming a phosphoric acid through a chemical change during the reaction" (hereinafter to be referred to as a phosphorus-containing compound) which is to be supplied to the reaction system in accordance with the present invention means any of phosphoric acids and phosphorus compounds capable of forming a phosphoric acid through a chemical reaction such as hydrolysis, oxidation, etc., including orthophosphoric acid, pyrophosphoric acid, metaphosphoric acid, phosphorous acid, hypophosphorous acid, phosphine, organic phosphoric acids, solid phosphoric acids, etc.

To the reaction system the phosphorus-containing compound may be supplied in any suitable manner.

For example, if the phosphorus-containing compound is water-soluble, it may uniformly be dissolved in water to be used for the reaction so that it is carried to the reaction system along with water.

If the phosphorus-containing compound is solid, for example, a solid phosphoric acid, this solid material may be charged in front of the catalyst layer. As steam is fed and made contact with the charged material, the latter generates a phosphoric acid, which is carried to the catalyst layer along with steam.

Furthermore, if the phosphorus-containing compound is gaseous, a gaseous mixture of the same and air may be fed to the catalyst layer.

The amount of the phosphorus-containing compound to be supplied may vary over a wide range. In general, the phosphorus-containing compound is supplied to that the amount of phosphorus contained in the compound is preferably 5 to 1 x 10-4 WtOo, more particularly 0.5 to I x 10-3 wt% on the basis of the total amount of water and an aliphatic alcohol fed during the reaction.

It will be appreciated therefore that the term "phosphoric acid" means "ortho-", "pyro-" or "meta-" phosphoric acid, and that the term "phosphorus compound capable of forming a phosphoric acid", refers to a phosphorus compound other than a phosphoric acid, which is capable of forming said phosphoric acid by chemical change. "Solid or organic phosphoric acid" are such phosphorus compounds, and may be formed, where appropriate, by polycondensation and carried, if desired, on an inert carrier.

A preferred catalyst according to the present invention has the following composition: PdaPbSbcXdOe wherein X denotes at least one element selected from the group consisting of potassium, sodium, lithium, rubidium, cerium, beryllium, lead, magnesium, calcium, strontium, zinc, barium, thorium, bismuth, chromium, iron, nickel, cobalt, vanadium, manganese, tin, uranium, and rhenium, the subscripts a, b, c, d and e denote the number of the Pd, P, Sb, X and 0 atoms, and wherein a is 1, b is 1 to 42, c is 0.1 to 15, d is 0.1 to 15 and e is a number determined by the valences of other elements and usually from 3.75 to 150.5.

A more preferred catalyst is a composition represented the above formula in which the ratio among a, b, c, d and e lies in the following range: a:b:c:d:e = 1 :(l-28):(0.2-l 0):(0. l-l0):(6.4-l0l).

The catalyst according to the present invention can be prepared in a conventional manner well knawn in the art, for example, by the following procedures.

In one case, compounds of respective constituent elements and the carrier, if a carrier is used, are mixed. The resultant mixture is evaporated to dryness and then the dried product is calcined.

In another case, a solid carrier is impregnated with compounds of each constituent element. This impregnated carrier is evaporated to dryness and then calcined.

In still another case, a solid carrier is impregnated with compounds of some constituent elements and then subjected to a heat treatment, preferably at a temperature of 200 700 C. The partly impregnated carrier is further impregnated with compounds of the other constituent elements. This twice impregnated carrier is evaporated to dryness and then calcined.

In any of the above-described procedures the calcination temperature lies preferably in a range of 3000-7000C, more preferably in a range of 4000-=-5500C.

If necessary, the calcination or the heat treatment may be carried out in an atmosphere of reducing agent such as hydrogen, hydrocarbon etc.

Examples of the compound of each constituent element are listed below.

Examples of palladium compound include palladium chloride, palladium nitrate, palladium sulfate, palladium black and the like.

Examples of phosphorus compound include orthophosphoric acid, phosphorous acid, hypophosphorous acid, pyrophosphoric acid, metaphosphoric acid, polyphosphoric acids, their salts, and the like.

Examples of antimony compound include oxides, hydroxides and chlorides of antimony, such as antimony dichloride, antimony pentachloride, antimony trioxide, and the like.

Examples of compound of the X constituent include nitrates, hydrochlorides, phosphates, sulfates, oxides, hydroxides of the X constituent, and the like.

More concrete procedures for the preparation of the catalyst of this invention are explained as follows: To an ammonia solution of any suitable palladium salt, for example palladium chloride, is added orthophosphoric acid (as 85% aqueous solution), phosphorous acid, hypophosphorous acid or any other phosphoric acid or salt thereof, yielding a clear solution. To this clear solution are further added a metal salt or oxide of antimony (such as antimony trioxide) and a metal salt or oxide of the X constituent, yielding an aqueous solution. Any suitable carrier is impregnated with such aqueous solution, evaporated to dryness and then calcined in air at 3000--7000C, preferably 4000--5500C for five or more hours.

The carrier which has been impregnated first with a palladium salt and thermally treated at a temperature of preferably 2000-7000C may be impregnated with phosphoric acid, antimony trioxide and X compound and then calcined.

Or, the carrier which has been impregnated with antimony trioxide and X compound and thermally treated may be impregnated with palladium chloride dissolved in ammonia water and then calcined in air and thermally treated in an atmosphere of reducing agent such as hydrogen. The resultant substance is impregnated with phosphorus compound and then calcined.

In either case the activity of the catalyst is not adversely affected.

The catalyst can include a carrier to lower the catalyst concentration, increase the catalyst strength or to enhance the economy of the catalyst. A suitable amount of a carrier may be impregnated with a small amount of the catalyst. Even a large amount of a carrier may be used.

As the carrier, may be employed inert substances such as silica sol, silica gel, silicon carbide, a-alumina, Alundum, Celite, boiling bubble stone, aluminum powder, silicahydro gel and the like.

The catalyst may be used in the form of spherical granules, pellets, particles crushed to suitable size, tablets etc.

The aliphatic alcohol used herein is, for example, methanol, ethanol, propanol and the like.

The molecular oxygen used herein is usually air. The oxygen may be diluted with an inert gas which does not adversely affect the reaction, such as nitrogen, carbon dioxide and the like.

To the reaction system methacrolein or acrolein and oxygen are fed as a gaseous feed mixture in such proportions that the molar ratio of methacrolein or acrolein to oxygen is preferably 1:(0.5--30), more preferably 1:(18).

When methacrolein or acrolein is oxidized by oxygen in the presence of the catalyst of the invention and in the absence of an aliphatic alcohol to produce methacrylic acid or acrylic acid, the presence of steam is indispensable. If steam is absent, the oxidation of methacrolein or acrolein to methacrylic acid or acrylic acid scarcely takes place. When an aliphatic alcohol is present according to the process of the invention, the destined products, methacrylic acid and methacrylate or acrylic acid and acrylate, can be obtained in high yields even in the absence of steam. The sensitivity of methacrylic acid and methacrylate or acrylic acid and acrylate is very high. However, by introducing a small amount of steam the conversion of methacrolein or acrolein is further accelerated and the yield of methacrylic acid and methacrylate or acrylic acid and acrylate is further increased.

The steam is added in the gaseous feed mixture in such proportions that the amount of steam is preferably 0.1 to 28 moles, more preferably 0.5 to 10 moles per mole of methacrolein or acrolein.

The aliphatic alcohol is preferably fed in an amount from 0.1 to 25 moles, especially 0.3 to 10 moles per mole of methacrolein or acrolein.

The temperature for carrying out the reaction is not so critical. The reaction may preferably be carried out at a temperature of 1800 to 3700 C, especially 200 to 3300 C.

The reaction can be carried out at atmospheric pressure or at lower or higher pressures. In general it is convenient to carry out the reaction at atmospheric pressure. A preferable range of pressure is 0.3 to 15 atm.

The gaseous feed mixture can be introduced at any desirable space velocity, preferably at a space velocity of 300 to 15,000 I-gas/l-cat.hr, especially 700 to 8,000 I-gas/l-cat.hr.

According to the present invention satisfactory results are obtained even when the reaction is carried out at space velocities as high as 2,000 to 8,000 I-gas/l-cat.hr.

Further the service life of the catalyst is maintained for a long period of time under such conditions.

The catalyst of the present invention may be applied in any form selected from a fixed bed, a fluidized bed and a moving bed.

The following examples are illustrative of the catalyst and the process of the present invention. In the examples, the terms "conversion of methacrolein or acrolein", "selectivity of methacrylic or acrylic acid", "selectivity of a methacrylate or acrylate", "yield of methacrylic or acrylic acid", "yield of a methacrylate or acrylate", and "space velocity" are defined as follows: Conversion of methacrolein or acrolein Moles of methacrolein or acrolein reacted = x100% Moles of methacrolein or acrolein fed Selectivity of methacrylic or acrylic acid Moles of methacrylic or acrylic acid produced x100% Moles of methacrolein or acrolein reacted Selectivity of a methacrylate or acrylate Moles of methacrylate or acrylate produced x100% Moles of methacrolein or acrolein reacted Yield of methacrylic or acrylic acid Moles of methacrylic or acrylic acid produced xl00% Moles of methacrolein or acrolein fed Yield of a methacrylate or acrylate Moles of methacrylate of acrylate produced ~ x100% Moles of methacrolein or acrolein fed Space Velocity (SV) The flow rate* of the gaseous feed mixture (l-gas/hr.) The volume of the charged catalyst (l-cat.) *calculated on a basis at the normal temperature and pressure Example 1.

While 16.0 g of Aerosil (SiO2) was heated and agitated, 0.4 g of antimony trioxide and 0.17 g of magnesium phosphate (III) were added. The mixture was concentrated by heating, then evaporated to dryness, and thereafter, dried at 100 C for eight hours. The dried mixture was impreganted with an aqueous ammonia solution containing 0.44 g of palladium chloride, evaporated to dryness, thereafter repeatedly washed with 10 liters of distilled water and dried. The dried product was subjected to a heat treatment in the air at 4500C for five hours and then thermally treated in an atmosphere of hydrogen at 450OC for five hours. The product was impregnated with 6.5 g of hypophosphorous acid (30%), evaporated to dryness. Thereafter, the dried product was calcined in the air at 4500C for five hours. The thus obtained product is named Catalyst A, the composition of which is represented by the formula: Pd1.0P12.3Sb1.0Mg0.5O33.75 A reaction tube of stainless steel having an inner diameter of 20 mm was filled with 10 ml of the Catalyst A and dipped in a bath of molten nitrate. With the use of this reaction tube filled with Catalyst A the oxidation of methacrolein was carried out for 120 days.

As the phosphorus-containing compound was used trimethyl phosphate in the form of a 0.1% solution (i.e. methanol-water solution). This solution was fed in an amount of 5 cc per hour.

A gaseous feed mixture contained methacrolein, methanol, oxygen, steam, nitrogen and phosphorus in a relative molar ratio of 1:1:2:5.5:18.1:1.8 x 10-3.

The gaseous feed mixture was supplied at a SV of 1565 l-gas/l-cat.hr.

The thus obtained products were determined by gas chromatography. The results are shown in Table 1.

TABLE 1 Selectivity of Temperature Conversion methacrylic acid Yield of Yield of Reaction of the of + methyl methacrylic methyl time nitrate bath methacrolein methacrylate acid methacrylate (day) ( C) (NO) (%) (%) (%) Initial stage 285 74.5 89.3 40.0 26.5 40 285 74.7 89.2 40.3 26.3 120 285 74.7 89.2 40.1 26.5 In the production of methacrylic acid and methyl methacrylate from methacrolein and methanol small amounts of by-products were derived, including 1.0% of acrylic acid, 0.5% of acetic acid, 2.5% of carbon dioxide and 4.0% of carbon monoxide.

Example 2.

Example 1 was repeated except that metaphosphoric acid in the form of a 0.1% solution (i.e. methanol-water solution) was used as the phosphorus-containing compound in place of trimethyl phosphate.

Other reaction conditions were the same as those of Example 1. The results are shown in Table 2.

TABLE 2 Selectivity of Temperature Conversion methacrylic acid Yield of Yield of Reaction of the of + methyl methacrylic methyl time nitrate bath methacrolein methacrylate acid methacrylate (day) (0C) (SO) (NO) (0my) (%) Initial stage 285 74.3 88.6 39.8 26.0 40 285 74.4 88.6 39.8 26.1 120 285 74.5 88.5 39.9 26.0 In the production of methacrylic acid and methyl methacrylate from methacrolein and methanol small amounts of by-products were derived, including 1.5% of acrylic acid, 0.7% of acetic acid, 2.0% of carbon dioxide and 4.3% of carbon monoxide.

Example 3.

A catalyst having the same composition with that of Example 1 was prepared in a similar way to that of Example 1, except that hypophosphorous acid was replaced by phosphorous acid.

With the use of the catalyst the reaction was carried out in a similar manner as described in Example 1. The results are shown in Table 3.

TABLE 3 Selectivity of Temperature Conversion methacrylic acid Yield of Yield of Reaction of the of + methyl methacrylic methyl time nitrate bath methacrolein acrylate acid acrylate (day) (0C) (So) (the) (NO) (NO) Initial stage 281 75.1 88.5 40.2 26.3 40 281 75.0 88.8 40.5 26.1 120 281 75.1 88.3 40.3 26.0 In the production of methacrylic acid and methyl methacrylate from methacrolein and methanol small amounts of by-products were derived, including 1.6% of acrylic acid, 0.4% of acetic acid, 2.3% of carbon dioxide and 4.3% of carbon monoxide.

Example 4.

The reaction described in Example 1 was repeated except that acrolein was used in place of methacrolein.

The results are shown in Table 4.

TABLE 4 Selectivity of Temperature Conversion acrylic acid Yield of Yield of Reaction of the of + methyl acrylic methyl time nitrate bath acrolein acrylate acid acrylate (day) ( C) (NO) (%) (No) (%) Initial stage 280 98.2 95.7 66.5 27.5 40 280 98.3 95.7 66.8 27.3 120 280 98.1 95.6 66.3 27.5 In the production of acrylic acid and methyl acrylate from acrolein and methanol small amounts of by-products were derived, including 1.0% of acetic acid, 1.5% of carbon monoxide, 1.2% of carbon dioxide and 0.5% of acetone.

Example 5.

The reaction was carried out under the same conditions as those of Example 1, except that the phosphorus-containing compound was not fed at all. The results are shown in Table 5.

Example 6.

The reaction was carried out under the same conditions as those of Example 4, except that the phosphorus-containing compound was not fed at all. The results are shown in Table 5.

TABLE 5 Selectivity of Temperature Conversion methacrylic Yield of Yield of Ex- Reaction of the of acid + methyl methacrylic methyl ample time nitrate bath methacrolein methacrylate acid methacrylate No. (day) ( C) (%) (%) (%) (%) 5 Initial stage 287 74.7 88.8 40.0 26.3 10 287 70.1 90.2 39.1 24.1 Selectivity of Temperature Conversion acrylic Yield of Yield of Ex- Reaction of the of acid + methyl acrylic methyl ample time nitrate bath acrolein acrylate acid acrylate No. (day) ( C) (%) (%) (%) (%) Initial stage 281 98.0 94.5 66.2 26.4 6 10 281 92.0 93.7 63.1 23.1 Examples 7-80.

The catalysts having the compositions shown in Table 6 were prepared in a manner similar to that described in Example 1, if necessary, using salts of the X constituent, ammonium metavanadate and rhenium chloride etc. With use of these catalysts the reactions were carried out under the same conditions as those of Example 1, except that the phosphorus-containing compound was not fed at all.

The results are shown in Table 6.

TABLE 6 Temperature Conversion Yield of Yield of Selectivity of of the of methacrylic methyl methacrylic acid + Example nitrate bath methacrolein acid methacrylate methyl methacrylate No. Catalyst Composition ( C) (%) (%) (%) (%) 7 Pd1P1Mg0.5Sb1O5.5 270 75.5 35.1 13.8 64.8 8 Pd1P5Mg1Sb1O16 273 75.6 35.5 14.0 65.5 9 Pd1P9Mg2Sb1O27 276 75.1 40.7 23.7 83.7 10 Pd1P16Mg5Sb7O56.5 279 70.5 40.2 20.8 86.5 11 Pd1P27Mg10Sb10O93.5 288 71.0 38.5 20.4 83.0 12 Pd1P8Mg0.1Sb0.2O21.4 276 74.0 35.7 15.9 70.0 13 Pd1P12Ba1Sb1O33.5 276 72.5 38.5 24.5 86.9 14 Pd1P6Ba0.5Sb2O19.5 272 75.5 35.7 18.6 71.9 15 Pb1P19Ba3Sb1O53 286 72.7 37.5 23.2 83.5 16 Pd1P23Ba1Sb3O64 296 73.5 36.5 20.7 77.8 17 Pd1P12Ca1Sb1O33.5 279 74.5 39.1 22.8 83.1 18 Pd1P21Ca1Sb2O57.5 281 73.5 40.5 20.3 82.7 19 Pd1P5Ca0.5Sb1O15.5 271 75.7 35.6 21.1 74.9 20 Pd1P27Ca6Sb7O85 295 72.5 34.5 18.9 73.7 21 Pd1P12K1Sb1O33 272 73.5 40.1 21.3 83.5 22 Pd1P16K3Sb2O45.5 274 72.5 38.5 20.5 81.4 TABLE 6 (Continued) Temperature Conversion Yield of Yield of Selectivity of of the of methacrylic methyl methacrylic acid + Example nitrate bath methacrolein acid methacrylate methylmethacrylate No. Catalyst Composition ( C) (%) (%) (%) (%) 23 Pd1P23K1Sb3O63.5 285 70.5 35.7 18.5 76.9 24 Pd1P3K0.3Sb0.5O9.4 270 76.6 33.6 19 4 69.2 25 Pd1P12Na1Sb1O33 270 74.5 38.5 23.1 82.7 26 Pd1P22Na2Sb2O60 280 73.3 40 1 22 7 85 7 27 Pd1P3Na5Sb7O21.5 268 74.7 35.4 15.7 68 4 28 Pd1P13Rb1Sb1O35.5 273 75.3 41.1 23.5 85 8 29 Pd1P20Rb3Sb2O55.5 286 73.5 39.7 21.4 83.1 30 Pd1P6Rb0.2Sb0.5O16.9 270 74.7 35.5 17.3 70 7 31 Pd1P12Sn0.5Sb1O33.3 276 75.6 40.7 23.8 85.3 32 Pd1P22Sn2Sb3O59.5 290 72.5 39.7 20.5 83.0 33 Pd1P3Sn0.2Sb4O14.8 271 74.5 36.7 17.7 73.0 34 Pd1P11Zn1Sb1O31 273 74.7 39.9 24.1 85.7 35 Pd1P21Zn4Sb2O60.5 288 73.5 38.5 23.3 84.1 36 Pd1P4Zn0.6Sb0.2O11.9 269 75.6 35.7 18.2 71 3 37 Pd1P12Ce1Sb1O33 277 76.5 39.7 23.5 82.6 38 Pd1P24Ce3Sb2O65.5 291 74.5 37.8 22.3 80.7 TABLE 6 (Continued) Temperature Conversion Yield of Yield of Selectivity of of the of methacrylic methyl methacrylic acid + Example nitrate bath methacrolein acid methacrylate methyl methacrylate No. Catalyst Composition ( C) (%) (%) (%) (%) 39 Pd1P3Ce6Sb8O23.5 267 76.4 34.7 20.3 72.0 40 Pd1P13Th1Sb1O37 273 74.5 40.0 19.5 79.9 41 Pd1P23Th4Sb4O72.5 287 73.3 39.7 17.5 78.0 42 Pd1P2Th0.1Sb3O10.7 266 76.9 34.5 18.8 69.3 43 Pd1P12Sr1Sb1O33.5 271 74.5 40.5 20.7 82.1 44 Pd1P23Sr3Sb2O64.5 289 72.5 38.9 19.5 80.6 45 Pd1P5Sr0.3Sb1O15.3 262 73.5 35.8 19.2 74.8 46 Pd1P13Bi2Sb2O39.5 277 74.8 39.7 24.5 85.8 47 Pd1P22Bi3Sb1O62 292 73.5 37.5 21.3 80.0 48 Pd1P6Bi0.5Sb6O25.8 272 75.5 35.0 17.9 70.1 49 Pd1P12Ni1Sb1O33.5 273 75.5 39.9 19.9 79.2 50 Pd1P24Ni2Sb4O69 286 74.4 39.8 19.0 79.0 51 Pd1P6Ni0.7Sb0.2O17 265 76.5 35.7 16.1 67.7 52 Pd1P13Fe1Sb0.5O35.8 271 74.6 40.0 21.5 82.4 53 Pd1P20Fe2Sb4O60 285 73.5 38.7 20.3 80.3 54 Pd1P27Fe4Sb8O86.5 300 75.5 39.9 17.1 75.5 TABLE 6 (Continued) Temperature Conversion Yield of Yield of Selectivity of of the of methacrylic methyl methacrylic acid+ Example nitrate bath methacrolein acid methacrylate methyl methacrylate No. Catalyst Composition ( C) (%) (%) (%) (%) 55 Pd1P12Co2Sb1O34.5 276 75.2 39.6 22.5 82.6 56 Pd1P24Co1Sb3O66.5 281 73.6 37.5 21.7 80.4 57 Pd1P2Co0.3Sb1O7.8 261 76.7 34.3 19.3 69.9 58 Pd1P12Cr1Sb1O34 273 76.5 41.3 23.0 84.0 59 Pd1P21Cr2Sb2O39.5 294 75.3 40.0 18.5 77.7 60 Pd1P4Cr0.7Sb1O13.6 263 76.7 35.7 17.8 69.8 61 Pd1P12Mn1Sb1O33.5 269 75.8 43.1 18.7 81.5 62 Pd1P19Mn3Sb4O57.5 273 75.1 40.0 16.2 74.8 63 Pd1P3Mn0.5Sb1O10.5 259 74.5 38.5 15.6 72.6 64 Pd1P13U1Sb1O37 273 73.1 39.7 20.5 82.4 65 Pd1P25U3Sb2O72.5 299 72.5 38.5 18.7 78.9 66 Pd1P2U0.5Sb6O16 265 75.5 37.9 16.5 72.1 67 Pd1P12Re1Sb1O34.5 265 75.7 41.5 23.5 85.9 68 Pd1P21Re3Sb2O62.5 268 74.3 39.7 22.7 84.0 69 Pd1P5Re1Sb0.5O16.3 251 73.8 39.0 18.5 77.9 70 Pd1P12Be0.5Sb1O33 273 74.5 38.5 23.1 82.7 TABLE 6 (Continued) Temperature Conversion Yield of Yield of Selectivity of of the of methacrylic methyl methacrylic acid + Example nitrate bath methacrolein acid methacrylate methyl methacrylate No. Catalyst Composition ( C) (%) (%) (%) (%) 71 Pd1P22Be2Sb1O59.5 296 73.7 37.0 21.5 79.4 72 Pd1P7Be6Sb10O39.5 267 75.7 36.3 17.5 71.1 73 Pd1P12Pb1Sb1O33.5 275 75.1 40.0 23.6 84.7 74 Pd1P21Pb2Sb2O58.5 287 75.2 39.5 22.9 83.0 75 Pd1P5Pb0.3Sb0.5O14.6 270 75.3 37.0 18.5 73.7 76 Pd1P12V1Sb1O35 273 76.1 39.0 23.3 81.9 77 Pd1P19V2Sb3O58 285 74.5 38.7 21.5 80.8 78 Pd1P25V5Sb5O83.6 291 73.1 36.6 17.6 74.1 79 Pd1P12Li1Sb0.6O32.4 273 74.7 40.0 23.1 84.5 80 Pd1P21Li2Sb1O56.0 280 73.5 39.9 21.3 83.3 Examples 81-102 Reactions using the catalysts of the said Examples were carried out under the same conditions as those of Example 1. The results are shown in Table 7.

TABLE 7 Selectivity of Temperature Conversion Yield of Yield of methacrylic acid Example Example No. Reaction of the of methacrylic methyl + methyl No. of time nitrate bath methacrolein acid methacrylate methacrylate catalyst used (day) ( C) (%) (%) (%) (%) 0 276 72.5 38.5 24.5 86.9 81 13 40 276 72.6 38.4 24.5 86.6 120 276 72.5 38.3 24.4 86.5 0 279 74.5 39.1 22.8 83.1 82 17 40 279 74.3 39.0 22.5 82.8 120 279 74.6 39.2 22.6 82.8 0 272 73.5 40.1 21.3 83.5 83 21 40 272 73.5 40.0 21.4 83.5 120 272 73.5 40.2 21.2 83.5 0 270 74.5 38.5 23.1 82.7 84 25 40 270 74.4 38.3 23.3 82.8 120 270 74.7 38.3 23.3 82.5 0 273 75.3 41.1 23.5 85.8 85 28 40 273 75.2 40.9 23.6 85.8 120 273 75.2 41.0 23.7 86.0 0 276 75.6 40.7 23.8 85.3 86 31 40 276 75.5 40.5 23.6 84.9 120 276 75.5 40.6 23.9 85.4 TABLE 7 (Continued) Selectivity of Temperature Conversion Yield of Yield of methacrylic acid Example No. Reaction of the of methacrylic methyl + methyl Example of time nitrate bath methacrolein acid methacrylate methacrylate No. catalyst used (day) ( C) (%) (%) (%) (%) 0 273 74.7 39.9 24.1 85.7 87 34 40 273 74.6 39.9 24.1 85.8 120 273 74.7 39.9 24.2 85.8 0 277 76.5 39.7 23.5 82.6 88 37 40 277 76.3 39.8 23.6 83.1 120 277 76.5 39.8 23.6 82.9 0 273 74.5 40.0 19.5 79.9 89 40 40 273 74.5 39.7 20.5 80.8 120 273 74.4 39.7 20.6 81.0 0 271 74.5 40.5 20.7 82.1 90 43 40 271 74.3 40.2 20.7 82.0 120 271 74.6 40.4 20.8 82.0 0 277 74.8 39.7 24.5 85.8 91 46 40 277 74.6 39.7 24.2 85.7 120 277 74.7 39.7 24.2 85.5 0 273 75.5 39.9 19.9 79.2 92 49 40 273 75.6 40.0 19.9 79.2 120 273 75.6 40.0 20.0 79.4 TABLE 7 (Continued) Temperature Conversion Yield of Yield of Selectivity of Example No. Reaction of the of methacrylic methyl methacrylic acid Example of time nitrate bath methacrolein acid methacrylate + methyl No. catalyst used (day) ( C) (%) (%) (%) methacrylate (%) 0 271 74.6 40.0 21.5 82.4 93 52 40 271 74.5 39.9 21.6 82.6 120 271 74.4 40.0 21.4 82.5 0 276 75.2 39.6 22.5 82.6 94 55 40 276 75.1 40.0 22.1 82.7 120 276 75.3 39.8 22.2 82.3 0 273 76.5 41.3 23.0 84.0 95 58 40 273 76.5 41.4 23.1 84.3 120 273 76.5 41.3 23.1 84.2 0 269 75.8 43.1 18.7 81.5 96 61 40 269 75.7 43.0 18.8 81.6 120 269 75.7 43.0 18.8 81.6 0 273 73.1 39.7 20.5 82.4 97 64 40 273 73.0 39.7 20.7 82.7 120 273 73.1 39.8 20.5 82.5 TABLE 7 (Continued) Selectivity of Temperature Conversion Yield of Yield of methacrylic acid Example No. Reaction of the of methacrylic methyl + methyl Example of time nitrate methacrolein acid methacrylate methacrylate No. catalyst used (day) ( C) (%) (%) (%) (%) 0 265 75.7 41.5 23.5 85.9 98 67 40 265 75.5 41.5 23.4 86.0 120 265 75.7 41.6 23.4 85.9 0 273 74.5 38.5 23.1 82.7 99 70 40 273 74.4 38.6 23.0 82.8 120 273 74.6 38.5 23.1 82.6 0 275 75.1 40.0 23.6 84.7 100 73 40 275 75.0 40.2 23.5 84.9 120 275 74.9 40.0 23.4 84.6 0 273 76.1 39.0 23.3 81.9 101 76 40 273 76.0 39.1 23.4 82.2 120 273 76.0 39.1 23.3 82.1 0 273 74.7 40.0 23.1 84.5 102 79 40 273 74.5 40.0 23.2 84.8 120 273 74.5 40.1 23.2 84.9 Examples 103-104.

The catalysts having the compositions shown in Table 8 were prepared in a manner similar as in Examples 7-80. With use of these catalysts the reactions were carried out under the same conditions as those of Example 1. The results are shown in Table 8.

TABLE 8 Selectivity of Temperature Conversion Yield of Yield of methacrylic acid Reaction of the of methacrylic methyl + methyl Example time nitrate bath methacrolein acid methacrylate methacrylate No Catalyst Composition (day) C (%) (%) (%) (%) 0 275 70.6 40.1 19.9 85.0 103 Pd1P12.3Sb1Mg0.5Rb0.5O34 40 275 70.1 40.0 19.6 85.0 120 275 70.5 40.0 19.9 85.0 0 272 75.5 39.0 21.0 79.5 104 Pd1P12Sb0.7V0.5K0.2O33.4 40 272 75.4 39.1 20.8 79.4 120 272 75.4 39.1 20.9 79.6 Examples 105-126.

Reactions described in Examples 4 were repeated except that catalysts having the compositions shown in Table 9 prepared in the same manner as in Examples 7-80 were used and the phosphorus-containing compound was not fed at all. The results are shown in Table 9.

TABLE 9 Temperature Conversion Yield of Yield of Selectivity of of the of acrylic methyl acrylic acid Example nitrate bath acrolein acid acrylate methyl acrylate No. Catalyst Composition ( C) (%) (%) (%) (%) 105 Pd1P12Ba1Sb1O33.5 281 97.7 66.3 26.1 94.5 106 Pd1P12Ca1Sb1O33.5 279 96.1 65.2 25.4 94.3 107 Pd1P16K3Sb2O45.5 286 92.3 63.1 23.3 93.6 108 Pd1P22Na2Sb2O60 276 92.5 64.3 23.1 94.5 109 Pd1P13Rb1Sb1O35.5 283 98.2 66.3 26.2 94.2 110 Pd1P12Sn0.5Sb1O33.3 274 91.3 61.1 22.6 91.7 111 Pd1P11Zn1Sb1O31 280 95.7 64.9 25.3 94.3 112 Pd1P12Ce1Sb1O33 282 93.7 64.5 24.2 94.7 113 Pd1P13Th1Sb1O37 285 98.0 65.3 25.7 92.9 114 Pd1P23Sr3Sb2O64.5 275 92.1 64.6 24.1 96.3 115 Pd1P13Bi2Sb2O39.5 286 93.7 64.7 25.1 95.8 116 Pd1P12Ni1Sb1O33.5 277 95.1 65.1 24.6 94.3 117 Pd1P13Fe1Sb0.5O35.8 281 94.1 62.3 25.1 92.9 118 Pd1P12Co2Sb1O34.5 282 95.2 63.3 24.7 92.4 119 Pd1P12Cr1Sb1O34 278 92.7 61.5 24.3 92.6 120 Pd1P19Mn3Sb4O57.5 271 95.5 62.1 23.7 99.8 TABLE 9 (Continued) Temperature Conversion Yield of Yield of Selectivity of of the of acrylic methyl acrylic acid + Example nitrate acrolein acid acrylate methyl acrylate No. Catalyst Composition ( C) (%) (%) (%) (%) 121 Pd1P13U1Sb1O37 277 93.1 60.7 24.1 91.1 122 Pd1P12Re1Sb1O34.5 272 98.3 67.3 26.0 94.9 123 Pd1P12Be0.5Sb1O33 278 95.7 61.5 24.5 89.9 124 Pd1P12Pb1Sb1O33.5 274 96.1 66.8 24.9 95.4 125 Pd1P12V1Sb1O35 273 97.0 65.9 23.9 92.6 126 Pd1P12Li1Sb0.6O32.4 277 92.1 61.3 24.0 92.7 Example 127.

The reactions described in Example 4 were carried out for 120 days using the same catalysts as in Examples 105-126. The results obtained after 120 days were nearly the same as those obtained at the initial stage. The yields of acrylic acid and methyl acrylate were not decreased for 120 days.

Example 128.

Examples 1 and 4 were repeated except that solid phosphoric acid (Celie/phosphorus=50/50) heat treated at 550 C was used as the phosphoruscontaining compound in place of trimethyl phosphate.

On the upper side of the catalyst layer consisting of 10 ml of Catalyst A was placed 5 ml of the solid phosphoric acid.

The results were nearly the same as those of Examples 1 and 4.

Example 129.

Examples 81-104 and 127 were repeated except that orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid and solid phosphoric acid were used as the phosphorus-containing compound in place of trimethyl phosphate, respectively, in each case. It has been found that the results are nearly the same as those of Examples 81-104 and 127.

Example 130.

Examples 1 and 4 were repeated except that the amount of the phosphorus containing compound supplied was changed. The amount of phosphorus contained in the compound was changed in the range of 0.5 wt% to lx 10-3 wt% based on total amount of water and methanol fed. The results were nearly the same as those of Examples 1 and 4.

Example 131.

A catalyst was prepared by following the procedure noted in Example 1, except that the impregnation order of palladium and phosphorus was changed.

Using this catalyst the reactions were carried out in the same manner as in Examples 1 and 4. The results were nearly the same as those of Examples 1 and 4.

Example 132.

A catalyst was prepared by following the procedure noted in Example 1, except that palladium and phosphorus were impregnated at the same time. Using this catalyst the reactions were carried out in the same manner as in Examples 1 and 4. The results were nearly the same as those of Examples 1 and 4.

Example 133.

16.0 g of Aerosil, 0.4 g of antimony trioxide, 0.17 g of magnesium phosphate, 6.5 g of hypophosphorous acid and 10 cc of an aqueous ammonia solution containing 0.44 g of palladium chloride were mixed together. The mixture was evaporated to dryness. The dried product was calcined in the air at 4500C for five hours. The catalyst thus obtained had a composition represented by the formula: Pd1P,2.3Sb1 MgOb033.75 Using this catalyst the reactions were carried out in the same manner as Examples I and 4. The results were nearly the same as those of Examples 1 and 4.

Example 134.

Example 1 was repeated except that the gaseous feed mixture was supplied at a SV of 4000 I-gas/l-cat. hr. The results are shown in Table 10.

TABLE 10 Selectivity of Temperature Conversion methacrylic Yield of Yield of Reaction of the of acid + methyl methacrylic methyl time nitrate bath methacrolein methacrylate acid methacrylate (day) ( C) (olO) (otto) (%) (%) Initial stage 296 67.7 89.5 37.2 23.4 40 296 67.6 89.3 37.4 23.0 120 296 67.6 89.4 37.4 23.0 Example 135.

Example 4 was repeated except that the gaseous feed mixture was supplied at a SV of 4000 I-gas/l-cat. hr. The results are shown in Table 11.

TABLE 11 Selectivity of Temperature Conversion methacrylic Yield of Yield of Reaction of the of acid T methyl methacrylic methyl time nitrate bath methacrolein methacrylate acid methacrylate (day) ( C) (%) (%) (%) (%) Initial stage 287 91.6 93.6 62.1 23.6 40 287 91.4 93.7 62.3 23.3 120 287 91.3 93.9 62.4 o3.3 Example 136-139.

The reaction described in Example I was repeated in the presence of Catalyst A with a varying molar ratio between reagents in a gaseous feed mixture. The results are shown in Table 12.

In table 12, gaseous feed mixtures B-E have the following relative molar ratio: Gaseous feed mixture methacrolein methanol oxygen steam nitrogen phosphorus B 1 1 2 0 18.1 1.8 .x 10-3 C 1 2 4 5.5 13.6 1.8 x 10-3 D 1 1 3 8.0 15.9 3.6 x 10-3 E 1 4 8 13.0 25.0 1.8 x 10-3 TABLE 12 Selectivity of Temperature Conversion methacrylic Yield of Yield of Gaseous of the of acid + methyl methacrylic methyl Example feed nitrate bath methacrolein methacrylate acid methacrylate No. mixture ( C) (%) (%) (%) (%) 136 B 300 66.5 88.7 37.5 21.5 137 C 276 76.5 83.1 35.2 28.4 138 D 277 77.6 80.2 40.0 22.2 139 E 273 63.5 87.8 39.6 16.2 Example 140-143.

The reaction described in Example 4 was repeated in the presence of Catalyst A with a varying molar ratio between reagents in the gaseous feed mixture. The results are shown in Table 13.

In Table 13. gaseous feed mixtures F-I have the following relative molar ratio: Gaseous feed mixture acrolein methanol oxygen steam nitrogen phosphorus F 1 1.5 2 0 18.1 1.8 x 10-3 G 1 2 4 7.5 13.6 3.6 x 10-3 H 1 1 8 12.5 21.6 1.8 x 10-3 1 1 4 5 3 12.3 5.4x10-3 TABLE 13 Selectivity of Temperature Conversion methacrylic Yield of Yield of Gaseous of the of acid + methyl acrylic methyl Example feed nitrate bath acrolein acrylate acid acrylate No. mixture ( C) (%) (%) (%) (%) 14Q F 287 94.8 91.7 58.1 28.8 141 G 272 98.8 93.0 64.9 27.0 142 H 270 98.7 90.2 67. t 21.7 143 I 282 95.1 92.7 60.1 28.1 The words "Alundum", "Celite", and "Aerosil" used herein are Registered Trade Marks.

Claims (11)

WHAT WE CLAIM IS:

1. A process for simultaneously producing methacrylic acid and a methacrylate and/or acrylic acid and an acrylate by reacting methacrolein and/or acrolein with an aliphatic alcohol and molecular oxygen in the vapor phase by using a catalyst comprising (1) palladium, (2) phosphorus, (3) antimony, (4) X and (5) oxygen wherein X denotes at least one element selected from potassium, sodium, lithium, rubidium, cerium, beryllium, lead, magnesium, calcium, strontium, zinc, barium, thorium, bismuth, chromium, iron, nickel, cobalt, vanadium, manganese, tin, uranium and rhenium.

2. A process as claimed in claim 1 wherein a phosphoric acid or a phosphorous compound capable of forming a phosphoric acid through chemical change during the reaction is concurrently supplied to the reaction system.

3. A process for simultaneously producing methacrylic acid and a methacrylate or acrylic acid and an acrylate by reacting methacrolein or acrolein with an aliphatic alcohol and molecular oxygen in the vapor phase by using a catalyst having the following composition: PdaPbSboXdoe wherein X denotes at least one element selected from potassium, sodium, lithium, rubidium, cerium, beryllium, lead, magnesium, calcium, strontium, zinc, barium, thorium, bismuth, chromium, iron, nickel, cobalt, vanadium, manganese, tin, uranium, and rhenium, the subscripts a, b, c, d and e denote the number of the Pd, P, Sb, X and 0 atoms, and wherein a is 1, b is 1 to 42, c is 0.1 to 15, d is 0.1 to 15 and e is a number determined by the valences of other elements and usually from 3.75 to 150.5.

4. A process as claimed in claim 3 wherein a is 1, b is I to 28, c is 0.2 to 10, d is 0.1 to 10 and e is 6.4 to 101.

5. A process as claimed in any preceding claim wherein said aliphatic alcohol is methanol.

6. A process as claimed in any one of claims 2 to 5 wherein said phosphoric acid is orthophosphoric acid, pyrophosphoric acid or metaphosphoric acid.

7. A process as claimed in any one of claims 2 to 5 wherein said phosphorus compound capable of forming a phosphoric acid through chemical change during the reaction is solid phosphoric acid or organic phosphoric acid as hereindefined.

8. A process as claimed in any preceding claim wherein a reactant is methacrolein.

9. A process as claimed in any one one of claims 1 to 7 wherein a reactant is acrolein.

10. A process as claimed in claim 1 and substantially as described in any one of the specific examples hereinbefore set forth.

11. Methacrylic acid, methacrylate, acrylic acid and acrylates whenever, produced by the process claimed in any preceding claim.