Method for producing a catalyst for unsaturated carboxylic acid synthesis

Abstract

A method for producing a catalyst for unsaturated carboxylic acid synthesis is proposed. The method includes: obtaining a dried product by drying and heat-treating a starting material mixed liquid in which supply source compounds of respective catalyst component elements are integrated; and forming a catalyst precursor by supporting powder to be supported on a carrier in the form of a particle aggregate. The powder to be supported is either the dried product or obtained from the dried product. The method further includes calcining the catalyst precursor to form the catalyst. The mass loss rate of the powder to be supported at 300 C. is less than 5 percent by mass, and the difference between the mass loss rate of the powder at 370 C. and the mass loss rate of the powder at 300 C. is not less than 1 percent by mass and not more than 6 percent by mass.

Claims

1. A method for producing a catalyst suitable for unsaturated carboxylic acid synthesis, the method comprising: (i) obtaining a dried product by drying and heat-treating a starting material mixed liquid in which supply source compounds of respective catalyst component elements are integrated; (ii) forming a catalyst precursor by supporting powder to be supported on a carrier comprising a particle aggregate, the powder to be supported being either the dried product or obtained from the dried product; and (iii) calcining the catalyst precursor to form the catalyst, wherein the heat-treating in the obtaining (i) is carried out at a heat treatment temperature of not less than 270 C. and not more than 330 C. for not less than 30 minutes and not more than 2 hours, wherein the powder to be supported, in the forming (ii), has a first mass loss rate, at 300 C., of less than 5 percent by mass, wherein a difference between a second mass loss rate of the powder to be supported at 370 C. and the first mass loss rate is not less than 1 percent by mass and not more than 6 percent by mass, wherein the first mass loss rate and the second mass loss rate are calculated from formula (I) based on masses of the powder to be supported before and after heating the powder to be supported to 300 C. and 370 C., respectively, in an air atmosphere until there is no change in mass:
R.sub.ML=(M.sub.0M.sub.H)/M.sub.0100(I), wherein R.sub.ML is mass loss rate in percent by mass, M.sub.0 is mass of the powder to be supported before heating in grams, and M.sub.H is mass of the powder to be supported after heating in grams, and wherein the catalyst comprises molybdenum as an essential component.

2. The method of claim 1, wherein the heat-treating in the obtaining (i) is carried out at a heat treatment temperature of not less than 270 C. and not more than 330 C. for not less than 30 minutes and not more than 3 hours.

3. The method of claim 1, wherein the starting material mixed liquid comprises sulfate.

4. The method of claim 1, further comprising: pulverizing the dried material.

5. The method of claim 1, wherein the catalyst is of formula (1):
Mo.sub.12V.sub.aX.sub.bCu.sub.cY.sub.dSb.sub.eZ.sub.fSi.sub.gC.sub.hO.sub.i(1), wherein X is Nb and/or W, Y is Mg, Ca, Sr, Ba, and/or Zn, Z is Fe, Co, Ni, and/or Bi, a to i are atomic ratios satisfying relations:
0<a12,
0b12,
0<c12,
0d8,
0e500,
0f500,
0g500, and
0h500, and i is a value satisfying the oxidation state of the other elements.

6. A method for producing acrylic acid, the method comprising: catalytically oxidizing acrolein in gas phase with oxygen-containing gas, using the catalyst produced by the method of claim 1.

7. The method of claim 1, wherein the starting material mixed liquid comprises sulfate.

8. The method of claim 1, further comprising: pulverizing the dried product from the obtaining (i).

9. The method of claim 2, further comprising: pulverizing the dried product from the obtaining (i).

10. The method of claim 3, further comprising: pulverizing the dried product from the obtaining (i).

11. The method of claim 7, wherein the catalyst is of formula (1):
Mo.sub.12V.sub.aX.sub.bCu.sub.cY.sub.dSb.sub.eZ.sub.fSi.sub.gC.sub.hO.sub.i(1), wherein X is Nb and/or W, Y is Mg, Ca, Sr, Ba, and/or Zn, and Z is Fe, Co, Ni, and/or Bi, a to i are atomic ratios satisfying relations:
0<a12,
0b12,
0<c12,
0d8,
0e500,
0f500,
0g500,
0h500, and i is a value satisfying the oxidation state of the other elements.

12. The method of claim 2, wherein the catalyst is of formula (1):
Mo.sub.12V.sub.aX.sub.bCu.sub.cY.sub.dSb.sub.eZ.sub.fSi.sub.gC.sub.hO.sub.i(1), wherein X is Nb and/or W, Y is Mg, Ca, Sr, Ba, and/or Zn, and Z is Fe, Co, Ni, and/or Bi, a to i are atomic ratios satisfying relations:
0<a12,
0b12,
0<c12,
0d8,
0e500,
0f500,
0g500,
0h500, and i is a value satisfying the oxidation state of the other elements.

13. The method of claim 3, wherein the catalyst is of formula (1):
Mo.sub.12V.sub.aX.sub.bCu.sub.cY.sub.dSb.sub.eZ.sub.fSi.sub.gC.sub.hO.sub.i(1), wherein X is Nb and/or W, Y is Mg, Ca, Sr, Ba, and/or Zn, and Z is Fe, Co, Ni, and/or Bi, a to i are atomic ratios satisfying relations:
0<a12,
0b12,
0<c12,
0d8,
0e500,
0f500,
0g500,
0h500, and i is a value satisfying the oxidation state of the other elements.

14. The method of claim 4, wherein the catalyst is of formula (1):
Mo.sub.12V.sub.aX.sub.bCu.sub.cY.sub.dSb.sub.eZ.sub.fSi.sub.gC.sub.hO.sub.i(1), wherein X is Nb and/or W, Y is Mg, Ca, Sr, Ba, and/or Zn, and Z is Fe, Co, Ni, and/or Bi, a to i are atomic ratios satisfying relations:
0<a12,
0b12,
0<c12,
0d8,
0e500,
0f500,
0g500,
0h500, and i is a value satisfying the oxidation state of the other elements.

15. A method for producing acrylic acid, the method comprising: catalytically oxidizing acrolein in gas phase with oxygen-containing gas, using the catalyst produced by the method of claim 7.

16. A method for producing acrylic acid, the method comprising: catalytically oxidizing acrolein in gas phase with oxygen-containing gas, using the catalyst produced by the method of claim 2.

17. A method for producing acrylic acid, the method comprising: catalytically oxidizing acrolein in gas phase with oxygen-containing gas, using the catalyst produced by the method of claim 3.

18. A method for producing acrylic acid, the method comprising: catalytically oxidizing acrolein in gas phase with oxygen-containing gas, using the catalyst produced by the method of claim 4.

19. A method for producing acrylic acid, the method comprising: catalytically oxidizing acrolein in gas phase with oxygen-containing gas, using the catalyst produced by the method of claim 5.

20. The method of claim 1, wherein the heat-treating in the obtaining (i) is carried out at a heat treatment temperature of not less than 270 C. and not more than 330 C. for not less than 30 minutes and less than 1 hour.

Description

EXAMPLES

(1) The present invention is described based on the following examples. The present invention is not limited in any way to these examples, and covers their modifications as long as they do not exceed the gist of the invention.

(2) <Measurement of Mass Loss Rate>

(3) 1 g of the powder to be supported was, immediately before being supported on the carrier, weighed and placed in a crucible and held at a predetermined temperature in a muffle furnace for 1 hour in the presence of air. The mass loss rate at the predetermined temperature was calculated based on the masses of the powder before and after heating.

(4) <Calculation of Conversion Rate, Selectivity, and Yield>

(5) The acrolein conversion rate, acrylic acid selectivity, and acrylic acid yield were calculated from the following equations.
Acrolein conversion (mole %)=(number of moles of acrolein reacted/number of moles of acrolein supplied)100
Acrylic acid selectivity (mole %)=(number of moles of acrylic acid produced/number of moles of acrolein converted)100
Acrylic acid yield (mole %)=(number of moles of acrylic acid produced/number of moles of acrolein supplied)100

Examples 1 to 3 and Comparative Examples 1 to 4

(6) <Preparation of the Catalyst>

(7) In each of Examples 1 to 3 and Comparative Examples 1 to 4, 2281 ml of warm water was placed in a vessel, and 76 g of ammonium metavanadate was added and dissolved. Then, 568 g of ammonium molybdate was added and dissolved to obtain a solution (hereinafter referred to as Solution A).

(8) Next, a solution of 80 g of copper sulfate dissolved in 115 ml of warm water was added to the solution A and mixed to obtain a uniformly mixed solution. Then, 52 g of niobium hydroxide and 16 g of antimony trioxide were added to the mixed solution, and the mixture was stirred to obtain the starting material mixed liquid.

(9) This starting material mixed liquid was spray-dried at 150 C., and then heat-treated in the atmosphere using a hot-air dryer at the heat-treatment temperature listed in Table 1 for the holding time listed in Table 1 to obtain the dried product.

(10) The dried product was pulverized to less than 200 m using a pulverizer with agitating blades to obtain the pulverized product. This pulverized product was used as the powder to supported. To this powder, 1.5% by weight of scaly glass was added, and they were uniformly mixed together. 100 g of spherical inert carrier of 4.9 mm in diameter, mainly composed of alumina-silica, was fed into a pan type granulator, and the mixture was added, alternately with 20% by weight aqueous solution of glycerin, such that the amount of the mixture supported was 40% by weight of the carrier. The catalyst precursor was thus obtained. The catalyst precursor was then calcined at 390 C. for 3 hours in an atmosphere of which air is diluted with nitrogen to 5% oxygen by volume. The composition ratio of the catalyst was as follows
Mo.sub.12V.sub.2.4Cu.sub.1.2Nb.sub.1Sb.sub.0.4
<Gas Phase Catalytic Oxidation of Acrolein>

(11) A reaction tube with an inner diameter of 21 mm was filled with 33 ml of the above-described catalyst. Then, a raw material mixed gas obtained by adding oxygen and nitrogen to the gas obtained from the gas phase of propylene, and having the following composition, was introduced into the reaction tube through its inlet, and the reaction was evaluated at a space velocity of 1,550/hr. The heating medium temperature was 250 C. The results of the reaction evaluation are shown in Table 1.

(12) The composition of the raw material mixed gas used is as follows: acrolein: 6 volume %, steam: 22 volume %, oxygen: 8 volume %, (nitrogen-containing inert gas+other gases): 64 volume %.

(13) TABLE-US-00001 TABLE 1 Example Comparative Example 1 2 3 1 2 3 4 Heat treatment temp. ( C.) 300 320 280 380 Not heated 340 260 Duration (Hr) 1 1 1 1 1 1 Mass loss rate A (mass %) 3.1 2.5 3.5 1.7 9.6 2.0 5.2 Mass loss rate B (mass %) 6.3 4.6 7 1.9 13.7 2.8 8.6 B A (mass %) 3.2 2.1 3.5 0.2 4.1 0.8 3.4 Acrolein conversion (%) 99.1 98.1 99.4 78.1 Not formable 85.7 87.0 Acrylic acid selectivity (%) 95.4 95.2 94.6 96.5 96.5 96.7 Acrylic acid yield (%) 94.5 93.4 94 75.4 82.7 84.1 In the table, Mass loss rate A represents the mass loss rate at 300 C., and Mass loss rate B, at 370 C.