Method for selective hydrogenation of unsaturated compound

Abstract

The present invention relates to a method for the selective hydrogenation of an unsaturated compound, particularly a method in an unsaturated compound or a mixture containing unsaturated compounds for increase of the light sulphides weight, hydrogenation of a polyunsaturated compound and isomerization of a monounsaturated compound. The method uses a supported catalyst. The supported catalyst contains at least one Group VIB non-noble metal oxide and at least one Group VIII non-noble metal oxide deposited on a carrier; and the catalyst has an optimized acid distribution on the surface of the catalyst, and more preferably has an optimized Group VIII/VIB metal ratio and a Group VIII non-noble metal density per unit of catalyst surface area.

Claims

1. A method for selective hydrogenation of an unsaturated compound, comprising increasing, by weight, an amount of light sulphides present in the unsaturated compound, and isomerizing a monounsaturated compounds during selective hydrogenation of the unsaturated compound, wherein the selective hydrogenation is carried out in the presence of a catalyst having at least one Group VIB metal component and at least one Group VIII non-noble metal component supported on a carrier, wherein: the Group VIB metal component comprises a Group VIB metal oxide in an amount of from 4% to 10% by weight of the catalyst; the Group VIII metal component comprises a Group VIII non-noble metal oxide in an amount of from % to 15% by weight of the catalyst; the catalyst comprises a B.sub.total/L.sub.total ratio of B acid to L acid in a surface acidity center of not more than 0.4; and a L.sub.weak/L.sub.strong ratio of weak L acid to strong L acid in the surface acidity center of 0.5 to 2.0; and the carrier is substantially alumina.

2. The method according to claim 1, wherein the Group VIII non-noble metal oxide and the Group VIB metal oxide is are in a molar ratio of from greater than 3.0 mole/mole to 5.0 mole/mole; and the Group VIII metal oxide per unit surface area of the catalyst is not less than 810.sup.4 g/m.sup.2.

3. The method according to claim 2, wherein the molar ratio of the Group VIII non-noble metal oxide to the Group VIB metal oxide in the catalyst is from 3.2 mole/mole to 5.0 mole/mole.

4. The method according to claim 1, wherein the Group VIB metal component comprises molybdenum, tungsten, or a combination thereof.

5. The method according to claim 1, wherein the Group VIII non-noble metal component comprises nickel, cobalt, or a combination thereof.

6. The method according to claim 1, wherein the Group VIB metal oxide is in an amount of from 6% to 8% by weight of the catalyst.

7. The method according to claim 1, wherein the Group VIII non-noble metal oxide is in an amount of from 8% to 12% by weight of the catalyst.

8. The method according to claim 1, wherein the Group VIII metal oxide per unit surface area of the catalyst is not less than 1010.sup.4 g/m.sup.2.

9. The method according to claim 1, wherein the ratio B.sub.total/L.sub.total of B acid to L acid in the surface acidity center of the catalyst is from 0.05 to 0.3.

10. The method according to claim 1, wherein the ratio L.sub.weak/L.sub.strong of weak L acid to strong L acid in the surface acidity center of the catalyst is from 0.5 to 1.5.

11. The method according to claim 1, comprising a total pore volume of the from 0.2 to 0.5 cm.sup.3/g.

12. The method according to claim 1, comprising a specific surface of from 50 to 200 m.sup.2/g.

13. The method according to claim 1, wherein the amount of alumina in the carrier is not less than 80 wt %.

14. The method according to claim 1, wherein the alumina comprises a crystal form selected from , , , and combinations thereof.

15. The method according to claim 1, wherein the catalyst is sulphurized before use, at a pressure of 0.5 to 3.0 MPa, a temperature of 200 to 500 C. and a space velocity of 0.5 to 5.0 h.sup.1.

16. The method according to claim 1, wherein the catalyst is used at a pressure of 1.0 to 5.0 MPa, a hydrogen/polyunsaturated compound molar ratio of 1 to 20 mole/mole, a space velocity of 2.0 to 6.0 h.sup.1 and a temperature of 50 to 250 C.

17. The method according to claim 16, wherein the pressure is 2.0 to 4.0 MPa, the hydrogen/polyunsaturated compound molar ratio is 1 to 10 mole/mole, the space velocity is 2.0 to 5.0 h.sup.1, and the temperature is 70 to 200 C.

18. The method according to claim 1, comprising a total pore volume of from 0.2 to 0.45 cm.sup.3/g.

19. The method according to claim 1, comprising a specific surface of from 50 to 150 m.sup.2/g.

20. The method according to claim 1, wherein the amount of alumina in the carrier is not less than 90 wt %.

Description

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Examples 15 and Comparative Examples 14

(1) Unless otherwise specified in the present invention, each carrier in examples and comparative examples indicates a carrier produced by subjecting it to calcination at 500 C. or high temperature treatment at 6001000 C. or treatment with water vapor at 400600 C. for 46 h, and modification with inorganic oxide precursors. Physical properties are as shown in Table 1.

(2) Unless otherwise specified, for all of the catalysts in examples and comparative examples, Group VIII non-noble metal salts and Group VIB metal salts are formulated into impregnating solution having different concentration according to the desired load of active metal, molar ratio of Group VIII non-noble metal oxides to Group VIB metal oxides and the like, and the catalyst carriers are impregnated therein, then aged for 12 h at normal temperature, followed by drying at 120 C. and calcination at 500 C., to produce catalyst products.

(3) For further illustrating the process for obtaining the catalyst, several examples are described herein in detail, and others can refer to the mentioned steps and produce desired catalysts as required.

Comparative Example 1

Catalyst Preparation

(4) 100 g of industrial grade SiO.sub.2Al.sub.2O.sub.3 powder (SiO.sub.2 content: 14%) was added with 50 g of water and then was subjected to kneading and extrusion molding. The resultant was then dried at 120 C. and calcinated at 600 C. for 4 h to produce a catalyst carrier.

(5) 14 g of industrial grade ammonium molybdate was added into 45 g of water, and stirred to be dissolved. Next, 75 g of industrial grade nickel nitrate, 12 g of industrial grade citric acid were added thereto and stirred to be dissolved, to produce an active metal impregnating solution for catalyst.

(6) The catalyst carrier was added into this impregnating solution, impregnated at normal temperature for 3 h. After that, the impregnated catalyst carrier was taken out and aged for 12 h, then dried at 120 C. and calcinated at 500 C. for 4 h to produce Catalyst A. This catalyst has a specific surface of 148 m.sup.2/g, a total pore volume of 0.41 cm.sup.3/g, MoO.sub.3 content of 6.4% and NiO content of 10.6%. More data for property analysis are shown in Table 1.

Comparative Example 2

Catalyst Preparation

(7) 100 g of industrial grade alumina powder was added with 50 g of water and then was subjected to kneading and extrusion molding. The resultant was then dried at 120 C. and calcinated at 500 C. for 4 h to produce a catalyst carrier.

(8) 14 g of industrial grade ammonium molybdate was added into 45 g of water, and stirred to be dissolved. Next, 75 g of industrial grade nickel nitrate, 12 g of industrial grade citric acid were added thereto and stirred to be dissolved, to produce an active metal impregnating solution for catalyst.

(9) The catalyst carrier was added into this impregnating solution, impregnated at normal temperature for 3 h. After that, the impregnated catalyst carrier was taken out and aged for 12 h, then dried at 120 C. and calcinated at 500 C. for 4 h to produce Catalyst B. This catalyst has a specific surface of 240 m.sup.2/g, a total pore volume of 0.38 cm.sup.3/g, MoO.sub.3 content of 6.4% and NiO content of 10.6%. More data for property analysis are shown in Table 1.

Example 1

Catalyst Preparation

(10) 100 g of industrial grade alumina powder was added with 50 g of water and then was subjected to kneading and extrusion molding. The resultant was then dried at 120 C. and calcinated at 500 C. for 4 h, and was further calcinated at 900 C. for 4 h to produce a catalyst carrier.

(11) 14 g of industrial grade ammonium molybdate was added into 45 g of water, and stirred to be dissolved. Next, 75 g of industrial grade nickel nitrate, 12 g of industrial grade citric acid were added thereto and stirred to be dissolved, to produce an active metal impregnating solution for catalyst.

(12) The catalyst carrier was added into this impregnating solution, impregnated at normal temperature for 3 h. After that, the impregnated catalyst carrier was taken out and aged for 12 h, then dried at 120 C. and calcinated at 500 C. for 4 h to produce Catalyst E. This catalyst has a specific surface of 101 m.sup.2/g, a total pore volume of 0.38 cm.sup.3/g, MoO.sub.3 content of 6.4% and NiO content of 10.6%. More data for property analysis are shown in Table 1.

Example 2

Catalyst Preparation

(13) 100 g of industrial grade alumina powder was added with 50 g of water and then was subjected to kneading and extrusion molding. The resultant was then dried at 120 C. and calcinated at 500 C. for 4 h, and was further treated in water vapor at 450 C. for 4 h to produce a catalyst carrier.

(14) 18 g of industrial grade ammonium molybdate was added into 45 g of water, and stirred to be dissolved. Next, 95 g of industrial grade cobalt nitrate, 16 g of industrial grade citric acid were added thereto and stirred to be dissolved, to produce an active metal impregnating solution for catalyst.

(15) The catalyst carrier was added into this impregnating solution, impregnated at normal temperature for 3 h. After that, the impregnated catalyst carrier was taken out and aged for 12 h, then dried at 120 C. and calcinated at 500 C. for 4 h to produce Catalyst F. This catalyst has a specific surface of 97 m.sup.2/g, a total pore volume of 0.35 cm.sup.3/g, MoO.sub.3 content of 9.1% and CoO content of 14.8%. More data for property analysis are shown in Table 1.

(16) The preparation methods for other catalysts would not to be repeated in detail, and respective catalysts were obtained according to desired performances.

(17) The physical properties and compositions of Catalysts A, B, C, D, E, F, G, H and I are as shown in Table 1.

(18) TABLE-US-00001 TABLE 1 Composition and Physical properties of Catalysts A, B, C, D, E, F, G, H and I Comparative Example Example 1 2 3 4 1 2 3 4 5 Catalyst No. A B C D E F G H I Carrier: SiO.sub.2 Al.sub.2O.sub.3 Al.sub.2O.sub.3 Al.sub.2O.sub.3 Al.sub.2O.sub.3 Al.sub.2O.sub.3 SiO.sub.2 SiO.sub.2 TiO.sub.2 (20%)- (2%)- (10%)- (5%)- Al.sub.2O.sub.3 Al.sub.2O.sub.3 Al.sub.2O.sub.3 Al.sub.2O.sub.3 Total pore 0.41 0.38 0.38 0.38 0.38 0.35 0.42 0.39 0.28 volume cm.sup.3/g Specific 148 240 101 101 101 97 96 142 165 surface m.sup.2/g MoO.sub.3 % 6.4 6.4 5.0 11.0 6.4 9.1 6.3 5.6 NiO % 10.6 10.6 5.8 4.0 10.6 11.7 11.5 13.2 WO.sub.3 % 7.0 CoO % 14.8 Molar ratio 3.2 3.2 2.2 0.7 3.2 3.1 3.6 5.0 4.5 of Group VIII metal/ Group VIB metal d.sub.Group VIII 0.7 0.4 0.6 0.4 1.1 1.5 1.2 0.8 0.8 .sub.element oxide (10.sup.3 g/m.sup.2) B.sub.total/L.sub.total 0.47 0 0 0 0 0 0.06 0.28 0 L.sub.weak/ 0.8 2.3 1.2 1.2 1.2 2.0 0.6 0.8 0.7 L.sub.strong

(19) Among these catalysts, catalysts E, F, G, H and I are the catalysts of the present invention. In contrast, catalysts A, B, C and D do not belong to the catalysts of the present invention.

(20) Hydrogenation of Catalysts

(21) A catalyst is charged into the middle part of a reaction tube having an inner diameter of 15 mm and a height of 320 mm, of which the upper and lower parts are filled with quartz sand of 2040 mesh for supporting.

(22) The catalyst is sulphurized before use. The sulphurizing oil is a mixture of cyclohexane and carbon disulfide (CS.sub.2 content is 2%). Sulphurization conditions are: a pressure of 2.0 MPa; a liquid hourly space velocity of 4 h.sup.1; hydrogen-to-oil volume ratio of 200:1; a temperature of 320 C.; and a sulphurization time of 12 h.

(23) The mixture of unsaturated compounds for testing has the following composition: 100 ppm by weight of propanethiol; 1% by weight of pentadiene; 3% by weight of 1-heptylene; and balance of cyclohexane.

(24) In the present invention, important technical parameters for evaluating catalyst performance are expressed as follows:
conversion rate of propanethiol %=(1propanethiol content in product/propanethiol content in raw material)*100
conversion rate of dienes %=(1dienes content in product/dienes content in raw material)*100
conversion rate of monoenes %=(1monoenes content in product/monoenes content in raw material)*100
isomerization rate of monoenes %=isomerized olefins content/(isomerized olefins content+alkanes content)*100
hydrogenation selectivity %=conversion rate of dienes/(conversion rate of dienes+conversion rate of monoenes)*100

(25) Hydrogenation treatment was performed under the conditions of a pressure of 2.0 MPa, a space velocity of 4 h.sup.1, a temperature of 120 C., and a hydrogen/diene molar ratio of 5:1. Next, the contents of propanethiol, dienes, monoenes, isomerized monoenes and alkanes in hydrogenated products were analyzed.

(26) Hydrogenation experiments were performed by using the catalysts of Comparative Examples 14 and Examples 15 respectively, and resulting experimental results are as shown in Table 2.

(27) TABLE-US-00002 TABLE 2 Experimental results of respective Comparative Examples and Examples Catalyst No. A B C D E F G H I Conversion rate of 100 99.0 98.0 98.5 100 100 100 100 99.0 propanethiol % Conversion rate of dienes % 87.2 85.1 75.7 82.7 88.5 88.5 89.5 89.8 87.8 Isomerization rate of 51.3 35.6 32.6 45.6 52.5 52.8 53.7 54.1 51.5 monoenes % Hydrogenation 95.8 96.6 97.1 97.6 98.5 99.0 99.5 99.3 98.0 selectivity %

(28) In the hydrogenation experiments of unsaturated compounds or a mixture containing unsaturated compounds, the method of the present invention has higher conversion rates of propanethiol and dienes, and isomerization rates of monoenes and hydrogenation selectivities are also apparently higher than those of the method in the Comparative Examples.

Examples 68

(29) The experimental results obtained by using the Catalyst E in Catalyst Example 1, utilizing the same sulfuration method and feedstock of identical composition except for changing reaction conditions, are as shown in Table 3.

(30) TABLE-US-00003 TABLE 3 Experimental results of Catalyst E under different conditions Example 6 7 8 Catalyst No. E E E Pressure MPa 1.5 2.0 3.0 Space velocity h.sup.1 2.0 4.0 3.0 Temperature C. 100 120 110 Hydrogen/diene 10.0 5.0 15.0 molar ratio Conversion rate of 100 100 100 propanethiol % Conversion rate of 89.2 88.5 88.2 dienes % Isomerization rate 53.1 52.5 52.7 of monoenes % Hydrogenation 99.1 98.5 98.7 selectivity %

(31) As can be seen from the above data, the catalyst illustrated in Example 1 has a good adaptability. The hydrogenation treatment of unsaturated compounds with this catalyst, which is operated in a wide range, can result in significantly high conversion rate of reaction products and selectivity.

INDUSTRIAL APPLICABILITY

(32) The present invention increases the conversion rate and the selectivity for hydrogenation of a polyunsaturated compound and increases the isomerization ratio of a monounsaturated compound by selecting active components of a catalyst, optimizing acid distribution on the surface of the catalyst, especially further selecting suitable Group VIII/VIB metal ratio for the catalyst and a density of Group VIII non-noble metal per unit surface area of the catalyst. Isomerized olefins often have higher stabilities and octane values, which are usually very important to improve the properties of the unsaturated compounds or a mixture containing the unsaturated compounds.

(33) By using the method of the present invention, the effect of hydrogenation treatment is improved notably, and the method provides higher conversion rate of thiols, higher saturation rate of dienes and better hydrogenation selectivity for dienes when it is used for hydrogenation of unsaturated compounds or a mixture containing the unsaturated compounds.