NO772298L - PROCEDURES FOR THE PREPARATION OF METHACRYLIC ACID FROM METHACROLEIN - Google Patents

Description

.Procedure in the manufacture of

methacrylic acid' from methacrolein

The present invention relates to a method for the production of methacrylic acid or acrylic acid by oxidation of methacrolein or acrolein with molecular oxygen in the vapor phase in the presence of a catalytic oxide of molybdenum, phosphorus, bismuth, copper, oxygen, a halogen selected from the group consisting of chlorine, bromine or .

■ iodine and optionally at least one element selected from the group consisting of Fe, Cr, Ni, Mn, Sb, Te, Rh and Pd.

A number of catalysts are known to be effective in oxidizing acrolein or methacrolein to acrylic acid or methacrylic acid. However, the yields obtained when using the catalysts for the production of methacrylic acid are low. The present invention is the result of a search for more effective and advantageous catalysts for the production of acrylic acid and methacrylic acid. Unexpectedly high yields of acrylic acid and methacrylic acid are obtained by vapor phase oxidation of acrolein and methacrolein with molecular oxygen in the presence of the new and applicable catalysts according to the invention.

The present invention therefore relates to a method for the production of acrylic acid or methacrylic acid by oxidation of acrolein or methacrolein with molecular oxygen in the vapor phase at a reaction temperature of 200° C to 500° C in the presence of an oxide catalyst, and optionally in the presence of steam, which method is characterized in that a catalyst of the formula is used as catalyst

wherein M is at least one element selected from the group consisting of iron, chromium, nickel, manganese, tellurium, palladium, antimony and rhodium,

X is a halogen atom selected from the group consisting of chlorine, bromine or iodine,

and where a, b and c are numbers from 0.001 to 10, d is from 9 to 10,

e is a positive number less than or equal to 5, f is a positive number of oxygen atoms necessary to satisfy the valence state of the other elements present.

The surprisingly advantageous catalysts according to the invention provide improved yields of acrylic acid and methacrylic acid from acrolein and methacrolein in an effective, convenient and economical manner at a relatively low temperature. The exotherm for the reaction is low, which enables easy reaction regulation.

The essential feature of the present invention is

the catalyst used. The catalyst can be any of the catalysts included in the formula stated above. The catalysts can be produced by a number of different methods which are described within the state of the art, such as sand-precipitation of soluble salts and calcination of the resulting product.

The catalysts according to the invention have preferred limits with regard to their composition. Preferred are catalysts in which a, b and c are numbers from 0.01 to 5 and e is from 0 to 1.0. Also preferred are catalysts in which -a is equal to 1 - 1.5, catalysts in which b is 0.1 - 0.5, catalysts in which c is 0.1 - 1.0 and catalysts in which e is 0.01 - 0.5 . Especially preferred are catalysts in which e is 0.01 - 0.20 and catalysts in which d is zero. Especially preferred are catalysts in which X is chlorine. Catalysts of particular interest are described in which chlorine,

bromine or iodine is present as an essential catalytic component. Especially preferred are catalysts in which chlorine is a necessary component.

When producing the catalysts, the different elements of the catalyst are combined and the final product is calcined to obtain the catalyst. A number of methods for combining the elements in the catalyst and calcining the resulting product are known in the art. The particular method for producing the catalysts is not critical.

However, it is the method for producing the catalysts that has been found to be preferred. A preferred method involves preparing the catalysts in an aqueous slurry in a solution of molybdenum and/or phosphorus containing components, after which the remaining components are added, this aqueous mixture is evaporated and the resulting catalysts are calcined. Suitable molybdenum compounds which can be used in the preparation of the catalysts of the above formula include molybdenum trioxide, phosphormolybdic acid, molybdic acid, ammonium heptamolybdate and the like. Suitable phosphorus compounds which are used in the preparation of the catalysts include ortho-phosphoric acid, metaphosphoric acid, triphosphoric acid, phosphorus pentabromide, phosphorus pentachloride and the like. The remaining components in the catalysts can be added as oxide, acetate, formate, sulphate, nitrate, carbonate, oxyhalide or halide and the like.

The catalysts according to the invention can also be prepared by mixing the catalytic components in an aqueous slurry or solution, heating the aqueous mixture to dryness and calcining the resulting catalyst.

Good results are obtained by refluxing phosphoric acid and molybdenum trioxide in water for approx. 1.5 to 4 hours', however, commercial phosphormolybdic acid can also be used effectively, adding the remaining components to the aqueous slurry and boiling to a thick paste, where at least one of the components is added as a halide or oxyhalide, drying at 110 - 120° C in air, and calcination of the resulting catalysts. It is not fully understood where the halogen atom is located in the catalytic structure. Infrared and X-ray analyzes show that the catalysts are mostly phosphoro-molybdate-based and that the halogen may be present as a molybdenum oxyhalide.

Excellent results are obtained by using a coated catalyst consisting mainly of an inert carrier material with a diameter of at least 20 microns and an outer surface, and a continuous coating of the active catalyst on the inert carrier which strongly adheres to the outer surface of the carrier. The special coated (catalyst) consists of an inner support material with an outer surface and a coating of active catalytic material on the outer surface.

The carrier material for the catalyst forms the inner core of the catalyst. This is mainly an inert carrier and can have basically any particle size, although a diameter of at least 20 microns is preferred. Particularly preferred according to the invention for use in a commercial

reactor are the carriers which are spherical and have a diameter of approx. 0.2 cm to approx. 2 cm. Examples of substantially inert carrier materials include: Alundum, silicon oxide, aluminum oxide, aluminum oxide-silicon oxide, silicon carbide, titanium dioxide and zirconium oxide. Particularly preferred among these supports are alundum, silicon oxide, aluminum oxide and aluminum oxide-silicon oxide.

The catalysts can contain essentially any amount of carrier and catalytically active material. The limits for this ratio are only set by the relative ability of the catalyst and the carrier material to adapt to each other. Preferred catalysts contain approx. 10 to 100% by weight catalytically active material based on the weight of the support.

Production of these coated catalysts can be carried out according to different methods. The main method of production of these catalysts is to partially wet the support material with a liquid. The carrier cannot be wetted on the outer surface of the total mass. It must be dry to the touch. If the carrier is moist, the catalytically active material will agglomerate in separate aggregates when the carrier is coated. These partially wetted supports are then contacted with a powder of the catalytically active material and the mixture is gently stirred until the catalyst is formed." The gentle stirring is most conveniently carried out by placing the partially wetted support in a rotary drum and adding the catalytically active material until nothing more is taken up by the bearer.This is done very economically.

Calcination of the catalyst is usually carried out by heating the dry catalytic components at a temperature of 300 -700° C. The special calcination for the desired results. tater varies with the different catalysts that are produced. The best calcination conditions for the catalysts according to the invention are shown in the following examples.

The reaction reactants according to the invention are methacrolein and oxygen. Molecular oxygen is normally supplied to the reaction in the form of air, mrn oxygen gas can also be used. Go. 0.5 to 4 mol of oxygen is normally added per moles of methacrolein.

The reaction temperature can vary according to which different catalysts are used. Temperatures of approx. 200 - 500°C, where temperatures of 250 - 370° are preferred.

The reaction is conveniently carried out in either a stationary bed or fluidized bed reactor.• The contact time can be as low as a fraction of a second or as high as 20 sec or more. The reaction can. carried out at atmospheric pressure, above atmospheric pressure or subatmospheric pressure where absolute pressures of 0.5 to 4 atmospheres are preferred.

When the catalyst is used in the reactor, it can be in charged or uncharged form. Suitable carrier materials include Alundum, silicon oxide, aluminum oxide, boron phosphate, zirconium oxide, silicon carbide or titanium oxide. ■

When the catalysts are reacted with acrolein or methacrolein in a stationary bed reactor, the active catalytic components can be coated on an inert carrier, - however, the catalytically active components can be mixed with one of the carrier materials specified above before coating the inert carrier.

It is also taken into account that acrolein or methacrolein can be oxidized by the present catalytic vapor phase reaction using the catalysts according to the invention, provided that a small amount of chlorine, iodine or bromine or an inorganic or organic halide is incorporated into the feed material.

When using the catalysts according to the invention in the production of methacrylic acid or acrylic acid, excellent yields are obtained in a. appropriate reaction with low amounts of by-products.

Example 1-9

Different catalysts according to the invention were prepared as follows:

Example 1

12 1, 32 0, 5 0, 25 0, 06 x

Part A. A slurry was prepared from 86.4 g (0.06 mol Mo) of molybdenum trioxide and 7.6 g (0.067 mol P) 85% phosphoric acid in 500 ml distilled water, boiled under reflux for 3 hours during the formation of phosphormolybdic acid which was yellow-green in colour. To this slurry was added 2.5 g (0.0125 mol Cu) of copper acetate without any change in color, followed by the addition of 7.9 g (0.025 mol Bi) of bismuth chloride dissolved in 4.0 ml of concentrated hydrochloric acid. The mixture was boiled to dryness, dried overnight at 110°C in air. The catalyst was ground and sieved to a 20/30 mesh fraction and calcined for 3 hours at 400°C in 40 ml/min air.

Part B. A large batch of this catalyst was prepared using 3500 ml of distilled water, 432 g of molybdenum trioxide, 38 g of phosphoric acid, 12.5 g of copper acetate, 39.5 g of bismuth chloride dissolved in 25 ml of concentrated hydrochloric acid. The mixture was heated overnight at 75°C, boiled to dryness, dried overnight at 110°C in an oven, ground and sieved and calcined for 3 hours at 400°C in 40 ml/min air.

Example 2 - 9

These catalysts were prepared in the same way as described in example 1.

Example - 2

12. 1, 32 0, 5 0, 25 0, 04 x

This catalyst - was prepared in the same way as in example 1, part B.

Example 3

Mo,0P, 0~,Bi„ cCu„ ot-Cl„ ncO

12 1 , 32 0 , 5 0 , 25 0 , 05 x

■This catalyst was prepared in the same way as described in example 1, with the exception that molybdenum trioxide and phosphoric acid were replaced with 118.3 g of commercially available phosphoro-molybdic acid and 1.84 g of 85% phosphoric acid.

Example 4

Mo-^P.. -.-Bi. cCun 0l-Cl„ nc-0

12 1 , 32 0 , 5 0 , 2b 0 , 05b x

This catalyst was prepared in the same way as described in example 1. with the exception that hydrochloric acid was replaced with 15 ml of concentrated nitric acid.

Example 5

Mo,-P, 00Bi- cCu- ocCln -,0

12 1 , 32 0 , 5 0 , 25 0 , 06 x

This catalyst was prepared in the same way as described in example 1, with the exception that bismuth chloride was replaced by 5.8 g (0.025 mol Bi) of bismuth oxide.

Example 6

Mo,-P, Q0Bin -Cu- ocO

12 1 , 32 0 , 5 0 , 25x

This catalyst was prepared in the same way as described in example 1, with the exception that no halogen was used in the preparation. The bismuth chloride was replaced with 5.8 g (0.025 mol Bi) bismuth oxide and hydrochloric acid was not used in the preparation.

Example 7

Mon „P, _ - Bi n Cu. OI-0

12 1 , 32 0 , 5 0 , 25x

This catalyst was prepared in the same way as described in example 6, with the exception that bismuth oxide was replaced with 12.1 g of Bi(NO3)3•<5H>2<0>.

Example 8

Mo,„P, -.-Cu' , [-Bi- ->Fe- , Cr» ,Ni- nCl- -.0

12 1 , 32 0 , 15 0 , 3 0 , 1 0 , 1 0 , 1 0 , 04 x

A slurry was prepared from 86.4 g (0.60 mol Mo) molybdenum trioxide and 7.6 g (0.067 mol P) 85% phosphoric acid in 500 ml distilled water. To this slurry was added 1.5 g (0.0075 mol Cu) copper acetate, 4.8 g (0.015 mol Bi) bismuth chloride, 5.0 ml concentrated hydrochloric acid, 1.4 g (0.005 mol Fe) ferric chloride hydrate, 0 .4 g (0.0 05 mol Cr) chromium oxide and 0.9 g (0.005 mol Ni) nickel acetate.

Example 9

Mo.„P1 00Cu- ~Bi- .Sb- rNi- ocCl- -.0

12 1, 32 0, 2 0, 4 0, 1 0, 05 0, 04 x

A slurry was prepared from 86.4 g (0.60 mol Mo) molybdenum trioxide and 7.6 g (0.067 mol P) 85% phosphoric acid in 500 ml distilled water and boiled under reflux for 3 hours

during heating, the color being yellow-green.

To this slurry was added 0.7 g (0.005 mol Sb) antimony oxide, and the color changed to dark green, and then 2.0 g (0.01 mol Cu) copper acetate, 6.3 g (0.02 mol Bi) bismuth chloride, 3.5 ml of concentrated hydrochloric acid and 0.4 g. (0.0025 mol Ni) nickel acetate.

Example 10 - 18'

Production of methacrylic acid using different catalysts according to the invention.

The catalysts were prepared in the same manner as above using appropriate ratios of the components.

A quantity of these catalyst particles was introduced into a 20 cm 3 fixed bed reactor consisting of a 1.3 cm stainless steel tube equipped with a 0.3 cm axial thermal wall. The reactor was heated to reaction temperature under a stream of air and was fed methacrolein/air/steam in a ratio of 1/6.2/5.2 and was fed over the catalyst at an apparent contact time of 4-5 sec. The reactor was run under the reaction conditions for 1 - 5 hours and the product was collected and analyzed. The reaction conditions and the results of the experiment are shown in Table I. The following definitions are used when measuring the carbon atoms in the feed and in the products.

Example 19 - 21

Effect of reaction temperature and proper calcination •of the catalysts in the production of methacrylic acid using the catalyst Mo,,P, _„Bin cCun -CC1~ A,0 .

2121.32 0.5 0.25 0.04 x

Examples 19 to 20

The catalyst according to Example 2 was calcined in the absence of air flow for 3 hours at 400° C. and was then reacted with methacrolein at 343° C. Another experiment was carried out at 377° C.

Example 21

The catalyst according to example 2 was reacted in the same way as described in example 19, with the exception that it was calcined in air and then reacted with methacrolein at 313°C.

These test results can be found in Table II.

Thus, the reaction temperature together with the correct calcination of the catalysts is critical with regard to obtaining advantageous yields of methacrylic acid in the method according to the invention.

Example 22 - 28

Production of methacrylic acid using catalysts according to the invention.

Example 22

A catalyst of the formula 20% Mo12Pl 32Bi0 5Cu0 25 CIq Q7°f + 80% Alundum was prepared as follows: A solution consisting of 105.9 g of ammonium heptamolybdate,

(NH4)6Mo7024.4H20 (0.6 mol Mo), and 500 ml of distilled water was boiled with stirring. To this solution was added 7.9 g of bismuth chloride, BiCl^ (0.025 mol Bi) as a solution in 15 ml of concentrated hydrochloric acid, and to this solution was added 2.5 g of copper acetate (0.0125 mol Cu), 7.7 h phosphoric acid (0.066 mol P) and 2.5 g hydrazine hydrate. The mixture was boiled to dryness and dried overnight at 110° C. This material was ground and sieved to a size less than 80 mesh and then coated on "Norton SA 5223" 3.17 mm's Alundum balls by wetting 50 g of Alundum with 1.8 g of water and 16.7 g of the powdery material was added in five equal portions. During and after each addition, the Alundum was rolled in a glass jar. The resulting product was then dried in an oven at 110-120°C overnight.

Example 23

20% Mo,0P, onBi„ cCun ocClA , ,0.p + 80% Alundum

12 1 , 32 0 , 5 0 , 25 0 , 16 r

This catalyst was prepared in the same way as described above, with the exception that hydrazine hydrate was omitted.

Example 24

15% Mo,0P, ~,0Bi„ cCu„ ncCln .,0, + 85% Alundum

12 1 , 32 0 , 5 0 , 25 0 , 06 f

The catalytically active material was prepared in the same manner as described in Example 1, Part A, ground and sieved to less than 50 mesh, and then coated onto Norton 5223 3.17 cm Alundum beads by wetting 25 g of Alundum with 1 .3 g of water and 4.17 g of the powdered catalytic material were added in a single portion. This resulting material was then dried in an oven at 125°C overnight.

Example 25

25% Mo,' P, 00Bi„ cCun TCClnncO^ + 75% Alundum

12 1 , 32 0 , 5 0 , 75 , 0 , 06 f

This catalyst was prepared in the same way as described in example 24, with the exception that Alundum was moistened with 1.8 g of water and 6.94 g of the powdered catalytic material was added in two equal portions.

Example 26

40% Mo,„P, 00Bi» cCun ocCln .,0, + 60% Alundum

12 1 , 32 0 , 5 0 , 25 0 , 06 . f

This catalyst was prepared in the same way as described in example 24, with the exception that Alundum was moistened with 2.1 g of water and 11.1 g of the powdered catalytic material was added in three equal portions. The catalyst was then dried in an oven at 110°C overnight.

Example 2 7

25% Mo, „P, -.-Bi. cCu. 0rCln nrC) + 75% Alundum

12 1 , 32 0 , 5 0 , 25 0 , 06 x

The catalytically active material was prepared in the same manner as described in Example 1, Part B, ground and sieved to less than 50 mesh, and then coated on 10/30 mesh particles of

■Norton SA 5223" Alundum in that 50 g of 10/30 mesh Alundum was wetted with 4 g of water and 16.7 g of the powdered catalytic material was added in three 3-gram portions and one 6.7-gram portion. This resulting material was dried at 110-120°C.

Example 28

35% Mo,„P, 00Bi„ cCun ncCl. -,0 + 65% Alundum

12 1 , 32 0 , 5 0 , 25 0 , 06 x

This catalyst was prepared in the same manner as described in Example 27, with the exception that Alundum was moistened with 2.2 g of water and 26.9 g of less than 80 mesh powdered catalytic material was added in four equal portions.

Example 29 - 48

Production of methacrylic acid using different coated catalysts according to the invention. ■

The catalysts were prepared in the same manner as above using suitable amounts of ingredients.

The resulting products were calcined for 3 hours at 400°C in air to form the active catalysts which consisted of the Alundum support with a continuous, highly adherent coating of the active catalyst.

Each catalyst prepared in examples 22 - 28 was introduced into the reactor as described in examples 10 - 18. The reactor was heated to reaction temperature under a stream of air after which a feed material of methacrolein/air/steam/nitrogen in the ratio 1/5 ,3/5,6/4,6 was added over the catalyst with an apparent contact time of 2.5 - 2.7 sec. The reaction conditions and results are shown in Table III.

Example 49

In the same manner as described in Examples 10 - 18, acrylic acid was prepared from acrolein using the catalyst according to Example 1, part A, Mo12P]_ 32Bi0 5Cu0 25C10 06°f ' The results of this experiment showed a conversion to acyl acid per pass of 75.1%, a total conversion of 85.3%, a selectivity of 88.0% at a reaction temperature of 317°C.

Claims (37)

1. Process for the production of acrylic acid or methacrylic acid in the oxidation of acrolein or methacrolein by molecular oxygen in the vapor phase at a reaction temperature of 200 - 500° C in the presence of an oxide catalyst and possibly in the presence of steam, characterized in that a catalyst is used as a catalyst of the formula: wherein M is at least one element selected from the group consisting of iron, chromium, nickel, manganese, tellurium, palladium, antimony, rhodium or mixtures thereof, X is a halogen selected from the group consisting of chlorine, bromine or iodine and where a, b and c are numbers from 0.001 - 10, d is from 0 - 10, e is from 0 - '5, f is a positive number of oxygen atoms which is necessary to satisfy the valence state of the other elements present. 2. Method according to claim 1, characterized in that the catalyst is calcined at a temperature of 325 - 450°C in air. 3. Method according to claim 1, characterized in that the reaction temperature is 250 - 370° C. 4. Method according to claim -1, characterized in that e is zero. 5. Method according to claim 1, characterized in that a, b and c are numbers from 0.01 to 5 and that e is from 0 to 1.0. 6. Method according to claim 1, characterized in that a is .1 - 1.5. 7. Method according to claim 1, characterized in that b is 0.1 - 0.5. 8- Method according to claim 1, characterized in that c is 0.1 - 1.0. 9- . Method according to claim 1, characterized in that e is 0.01 - 0.2. 10. Method according to claim 1, characterized in that e is 0.1 - 0.5. 11. Method according to claim 10, characterized in that M is at least one element selected from the group consisting of Fe, Cr and Ni. 12. Method according to claim 10, characterized in that X is chlorine. 13. Method according to claim 10, characterized in that Mo Bi P_ ot-Cu„ oc is used as catalyst. s e r t d et J120 .5 0.25 0.25 C10.06°f* . 14. Method according to claim 1, characterized in that the catalyst is coated on an inert carrier. 15. Method according to claim 14, characterized in that the catalyst mainly consists of an inert carrier material with a diameter of at least 20 microns and an outer surface, and a continuous coating of the active catalyst strongly adhering to the outer surface of the carrier. 16. Method according to claim 15, characterized in that the active catalyst is 10 to 100% by weight of the inert carrier. 17. Method according to claim 15, characterized in that the carrier is selected from the group consisting of silicon oxide, aluminum oxide, Alundum, aluminum oxide-silicon oxide, silicon carbide, titanium dioxide and xirnium oxide. 18. Method according to claim 15, characterized in that the particle size of the inert carrier is 0.2 cm to 2 cm. 19- Method according to claim 1, characterized in that methacrolein is reacted. 20. Method according to claim 1, characterized in that acrolein is reacted. 21- Catalyst composition, characterized in that it has the general formula: wherein M is at least one element selected from the group consisting of iron, chromium, nickel, ■manganese, tellurium, palladium, antimony and rhodium, X is a halogen selected from the group consisting of chlorine, bromine or iodine, and where a, b and c are numbers from.0.001 to 10, d is from 0 to 10, e is a positive number less than or equal to 5, f is a positive number ' number of oxygen atoms necessary to satisfy the valence state of the other elements present. 22. Catalyst according to claim 21, characterized in that it is calcined at a temperature of 325 - 450° C in air. 23. Catalyst according to claim 21, characterized in that a, b and c are numbers from 0.01 to 5. and that e is a positive ■ numbers less than or equal to 1.0. 24. Catalyst according to claim 21, characterized in that a is 1 - 1.5. 25. Catalyst according to claim 21, characterized in that b is 0.1 to 0.5. 26. Catalyst according to claim 21, characterized in that c is 0.1 to 1.0. '27. Catalyst according to claim 21, characterized in that e is 0.01 to 0.5. 28. Catalyst according to claim 21, characterized in that e is 0.01 to 0.2. 29.. Catalyst according to claim 21, characterized in that d is equal to zero. 30. Catalyst according to claim 21, characterized in that M is nickel in combination with at least one element selected from the group consisting of chromium, manganese, tellurium, palladium, antimony and rhodium. 31. Catalyst according to claim 21, characterized in that M is a mixture of iron, nickel and chromium. 3.2. Catalyst according to claim 21, characterized in that X is chlorine. 33. Catalyst according to claim 21, characterized in that it is coated on an inert carrier. 34. Catalyst according to claim 33, characterized in that it consists mainly of an inert carrier material with a diameter of at least 20 microns and an outer surface, and a continuous coating of the active catalyst strongly adhering to the outer surface of the carrier. 35. Catalyst according to claim 34, characterized in that the active catalyst is 10-100% by weight of the inert carrier. 36. Catalyst according to claim 34, characterized in that the carrier is selected from the group consisting of silicon oxide, aluminum oxide, Alundum, aluminum oxide-silicon oxide, silicon carbide, titanium dioxide and zirconium oxide. 37. Catalyst according to claim 34, characterized in that the particle size of the inert carrier is 0.2 cm to 2 cm.