Catalysts containing copper, zinc oxide, alumina and silica

Abstract

A catalyst suitable for use in carbon oxide conversion reactions is provided. The catalyst is in the form of a shaped unit formed from an oxidic catalyst powder and contains 30-70% by weight of copper oxide, zinc oxide, alumina and silica. The catalyst has a Si:Al atomic ratio in the range 0.005:1 to 0.15:1, a BET surface area >105 m.sup.2/g and a copper surface area >37 m.sup.2/g catalyst. The catalyst is prepared by a co-precipitation method using an alumina sol.

Claims

1. A catalyst, suitable for use in carbon oxide conversion reactions, in the form of a shaped unit formed from an oxidic catalyst powder, said catalyst comprising (i) 30-70% by weight of copper oxide (CuO) based on a total weight of the catalyst, (ii) zinc oxide (ZnO), (iii) alumina and (iv) silica, wherein the catalyst has a Si: Al atomic ratio in a range 0.005:1 to 0.15:1, a BET surface area as determined by nitrogen physisorption 115 m.sup.2/g and a copper surface area >37 m.sup.2/g catalyst.

2. The catalyst according to claim 1 wherein the catalyst is a methanol synthesis catalyst comprising copper oxide in an amount in a range 50 to 70% by weight.

3. The catalyst according to claim 2 wherein a weight ratio CuO:ZnO is in a range of 2:1 to 3.5:1.

4. The catalyst according to claim 2 wherein the catalyst contains 20 to 30% by weight of the zinc oxide, based on a total weight of the catalyst.

5. The catalyst according to claim 1 wherein the catalyst contains 5 to 20% by weight of the alumina, based on a total weight of the catalyst.

6. The catalyst according to claim 1 wherein the catalyst has a copper surface area 40 m.sup.2/g.

7. The catalyst according to claim 1 wherein the catalyst further comprises one or more promoter compounds that are compounds of Mg, Co, Mn, V, Ti, Zr or rare earth metals.

8. The catalyst according to claim 1 wherein the catalyst contains 0.05 to 1.50% by weight of the silica, based on a total weight of the catalyst.

9. The catalyst according to claim 1 wherein the Si: Al atomic ratio is in a range of 0.03:1 to 0.07:1.

10. The catalyst according to claim 1 wherein a Si: Cu atomic ratio is in a range of 0.001:1 to 0.018:1.

11. The catalyst according to claim 1, wherein the BET surface area of the catalyst, as determined by nitrogen physisorption, is 115 m.sup.2/g up to about 140 m.sup.2/g.

12. A carbon oxides conversion process which comprises reacting a carbon oxide containing process gas containing at least one of carbon monoxide and carbon dioxide and additionally containing hydrogen and/or steam, in the presence of a catalyst according to claim 1.

13. The carbon oxides conversion process according to claim 12 wherein the process is selected from methanol synthesis and the water-gas shift reaction.

Description

EXAMPLE 1

(1) An oxidic catalyst with the molar ratio Cu:Zn:Al:Mg:Si of 4.4:1.7:1.0:0.2:0.04 and a copper oxide content of 64.4 wt. % was prepared by co-precipitation of a mixed metal nitrate solution comprising nitrates of copper, zinc and magnesium with a potassium carbonate solution, with simultaneous addition of a mixture of an alumina sol and a silica sol to the precipitation vessel, at a pH of 6.3-6.8 and a temperature between 65-70 C. The resulting precipitate was aged for up to 2 hours at 65-70 C., filtered, washed with demineralised water, dried and calcined in air at 330 C. for 6 hours.

EXAMPLE 2

(2) An oxidic catalyst with the molar ratio Cu:Zn:Al:Si of 5.1:1.9:1.0:0.04 and a copper oxide content of 66.1 wt. % was prepared as described in Example 1, without magnesium nitrate, and with calcination in air at 300 C. for 6 hours.

EXAMPLE 3

(3) An oxidic catalyst with the molar ratio Cu:Zn:Al:Mg:Si of 4.5:1.7:1.0:0.2:0.006 and a copper oxide content of 64.5 wt. % was prepared as described in Example 1 with calcination in air at 305 C. for 6 hours.

EXAMPLE 4

(4) An oxidic catalyst with the molar ratio Cu:Zn:Al:Mg:Si of 4.5:1.7:1.0:0.2:0.08 and a copper oxide content of 64.2 wt. % was prepared as described in Example 1 with calcination in air at 305 C. for 6 hours.

EXAMPLE 5

(5) An oxidic catalyst with the molar ratio Cu:Zn:Al:Mg:Si of 6.7:2.5:1.0:0.3:0.11 and a copper oxide content of 66.1 wt. % was prepared as described in Example 1 with calcination in air at 305 C. for 6 hours.

EXAMPLE 6

(6) An oxidic catalyst with the molar ratio Cu:Zn:Al:Mg:Si of 3.3:1.2:1.0:0.1:0.06 and a copper oxide content of 62.2 wt. % was prepared as described in Example 1 with calcination in air at 305 C. for 6 hours.

EXAMPLE 7

(7) An oxidic catalyst with the molar ratio Cu:Zn:Al:Mg:Si of 5.4:2.0:1.0:0.2:0.04 and a copper oxide content of 65.9 wt. % was prepared by co-precipitation of a mixed metal nitrate solution comprising nitrates of copper, zinc and magnesium with a potassium carbonate solution, with simultaneous addition of a silica-doped alumina sol to the precipitation vessel, at a pH of 6.3-6.8 and a temperature between 65-70 C. The resulting precipitate was aged for up to 2 hours at 65-70 C., filtered, washed with demineralised water, dried and calcined in air at 330 C. for 6 hours.

EXAMPLE 8

(8) An oxidic catalyst with the molar ratio Cu:Zn:Al:Si of 4.3:1.7:1.0:0.04 and a copper oxide content of 64.6 wt. % was prepared by co-precipitation of a mixed metal nitrate solution comprising nitrates of copper and zinc and a silica sol, with a potassium carbonate solution, with simultaneous addition of an alumina sol to the precipitation vessel, at a pH of 6.3-6.8 and a temperature between 65-70 C. The resulting precipitate was aged for up to 2 hours at 65-70 C., filtered, washed with demineralised water, dried and calcined in air at 300 C. for 6 hours.

EXAMPLE 9

(9) An oxidic catalyst with the molar ratio Cu:Zn:Al:Si of 4.0:1.5:1.0:0.03 and a copper oxide content of 64.4 wt. % was prepared by co-precipitation of a mixed metal nitrate solution comprising nitrates of copper and zinc with a potassium carbonate solution, with simultaneous addition of an alumina sol to the precipitation vessel, at a pH of 6.3-6.8 and a temperature between 65-70 C. A silica sol was added to the resulting co-precipitate. The resulting mixture was aged for up to 2 hours at 65-70 C., filtered, washed with demineralised water, dried and calcined in air at 300 C. for 6 hours.

EXAMPLE 10

(10) An oxidic catalyst with the molar ratio Cu:Zn:Al:Mg:Si of 4.4:1.7:1.0:0.2:0.04 and a copper oxide content of 63.2 wt. % was prepared by co-precipitation of a mixed metal nitrate solution comprising nitrates of copper, zinc and magnesium with a potassium carbonate solution, with simultaneous addition of an alumina sol containing a soluble potassium silicate to the precipitation vessel, at a pH of 6.3-6.8 and a temperature between 65-70 C. The resulting precipitate was aged for up to 2 hours at 65-70 C., filtered, washed with demineralised water, dried and calcined in air at 305 C. for 6 hours.

EXAMPLE 11

(11) An oxidic catalyst with the molar ratio Cu:Zn:Al:Si of 4.2:1.6:1.0:0.03 and a copper oxide content of 64.4 wt. % was prepared by co-precipitation of a mixed metal nitrate solution comprising nitrates of copper and zinc with a solution comprising potassium carbonate and potassium silicate, with simultaneous addition of an alumina sol to the precipitation vessel, at a pH of 6.3-6.8 and a temperature between 65-70 C. The resulting precipitate was aged for up to 2 hours at 65-70 C., filtered, washed with demineralised water, dried and calcined in air at 300 C. for 6 hours.

EXAMPLE 12

(12) An oxidic catalyst with the molar ratio Cu:Zn:Al:Mg:Si of 4.2:1.2:1.0:0.2:0.04 and a copper oxide content of 67.8 wt. % was prepared by co-precipitation of a mixed metal nitrate solution comprising nitrates of copper, zinc and magnesium with a sodium carbonate solution, with simultaneous addition of an alumina sol and a silica sol to the precipitation vessel, at a pH of 6.3-6.8 and a temperature between 65-70 C. The resulting precipitate was aged for up to 2 hours at 65-70 C., filtered, washed with demineralised water, dried and calcined in air at 300 C. for 6 hours.

COMPARATIVE EXAMPLE 1

(13) An oxidic catalyst with the molar ratio Cu:Zn:Al:Si of 3.8:2.2:1.0:0.04 and a copper oxide content of 56.6 wt. % was prepared following the procedure outlined in U.S. Pat. No. 6,048,820 Example 2. A mixed metal nitrate solution containing nitrates of copper, zinc and aluminium and a silica sol, and a solution of sodium carbonate were added simultaneously to demineralised water in the precipitation vessel at room temperature with stirring. The resulting precipitate was aged at room temperature for 24 hours, filtered, washed with demineralised water, dried and calcined in air at 600 C. for 2 hours.

COMPARATIVE EXAMPLE 2

(14) An oxidic catalyst with the molar ratio Cu:Zn:Al:Si of 3.8:2.2:1.0:0.04 and a copper oxide content of 56.6 wt. % was prepared as described in Comparative Example 1 with calcination at 305 C. for 6 hours.

COMPARATIVE EXAMPLE 3

(15) An oxidic catalyst with the molar ratio Cu:Zn:Al:Si of 3.3:1.5:1.0:0.01 and a copper oxide content of 60.1 wt. % was prepared following the procedure outlined in CN101306369A Example 5. An aluminium nitrate solution was co-precipitated with a solution of sodium carbonate and sodium silicate at a pH of 7.0-7.2 and a temperature of 80 C. to form Precipitate A. This material was not a stable colloidal suspension and sedimented over several hours. Analysis showed the D50 average particle size to be 226 nm. Separately, a solution of copper and zinc nitrate was co-precipitated with a sodium carbonate solution at a pH of 7.0-7.2 and a temperature between 65-70 C. to form Precipitate B. Precipitate A was added to Precipitate B in a 1:7 ratio by volume. The resulting mixture was aged at 70 C. for 2 hours, filtered, washed with demineralised water, dried and calcined in air at 340 C. for 4 hours.

COMPARATIVE EXAMPLE 4

(16) An oxidic catalyst as described in U.S. Pat. No. 4,788,175 with the molar ratio Cu:Zn:Al:Mg of 4.4:1.6:1.0:0.2 and a copper oxide content of 64.2 wt. % was prepared by co-precipitation of a mixed metal nitrate solution comprising nitrates of copper, zinc and magnesium with a solution of potassium carbonate, with simultaneous addition of an alumina sol to the precipitation vessel, at a pH of 6.3-6.8 and a temperature between 65-70 C. The resulting precipitate was aged for up to 2 hours at 65-70 C., filtered, washed with demineralised water, dried and calcined in air at 330 C. for 6 hours.

COMPARATIVE EXAMPLE 5

(17) An oxidic catalyst with the molar ratio Cu:Zn:Al:Si of 6.2:3.4:1.0:0.08 and a copper oxide content of 59.5 wt. % was prepared following the procedure outlined in U.S. Pat. No. 9,314,774 Example 2. A solution of sodium carbonate was added to a mixed metal nitrate solution containing nitrates of copper, zinc and aluminium and a silica sol, at room temperature with stirring. The resulting precipitate was aged at 70 C. for 2 hours, filtered, washed with demineralised water, dried and calcined in air at 350 C. for 2 hours.

COMPARATIVE EXAMPLE 6

(18) An oxidic catalyst with the molar ratio Cu:Zn:Zr:Al:Si of 4.8:3.3:1.6:1.0:0.12 and a copper oxide content of 42.5 wt. % was prepared following the procedure outlined in U.S. Pat. No. 9,314,774 Comparative Example 5. A mixed metal nitrate solution containing nitrates of copper, zinc, aluminium and zirconium and a silica sol, and a solution of sodium carbonate were added simultaneously to demineralised water at room temperature with stirring. The resulting precipitate was aged at 70 C. for 2 hours, filtered, washed with demineralised water, dried and calcined in air at 400 C. for 2 hours.

(19) Microreactor Testing

(20) Each of the catalyst samples were crushed and sieved to a particle size fraction of 0.6-1.0 mm. The experiments used a conventional micro-reactor. The crushed catalyst samples were fully reduced with a gas mixture of 2% v/v hydrogen in nitrogen at 225 C. A process gas mixture with a gas composition of 6% v/v CO, 6% v/v CO.sub.2, 9% v/v N.sub.2 and 79% v/v H.sub.2 was then introduced over the catalyst samples. The reduced catalyst samples were exposed to the process gas mixture at 225 C., 40,000 L/hr/kg, 50 barg at the start of life. After a period, catalyst samples were exposed to deactivating conditions over 300 C. to simulate harsh operating conditions and accelerate the ageing effects. Analysis flow scans of product gases were performed at the start of life and after the catalyst had been held at deactivation conditions. Analysis flow scans were performed by varying the mass velocity at 225 C., 50 barg. An infra-red analyser was used to determine the % v/v concentration of the exit gas streams from the reactors. The analysis flow scan data was used to calculate the relative activity of the test material against a reference catalyst, selected in these experiments to be Comparative Example 1. The relative activities are calculated from the ratio of the flow rates through each catalyst at constant conversion relative to the flow rate through the standard catalyst. The results are set out in the following table:

(21) TABLE-US-00002 Cu BET Surface Relative Relative Surface CuO Area Si:Al Activity to Activity to Al Area content (m.sup.2/g atomic Comp. Ex. 1 Comp. Ex. 1 Sample Source (m.sup.2/g) (wt %) catalyst) ratio after 16 h after 340 h Example 1 sol 119.4 64.4 52.8 0.04 1.60 1.46 Example 2 sol 121.3 66.1 42.7 0.04 1.61 1.39 Example 3 sol 120.5 64.5 52.1 0.006 1.61 1.31 Example 4 sol 120.8 64.2 54.7 0.08 1.57 1.38 Example 5 sol 115.5 66.1 52.9 0.11 1.60 1.29 Example 6 sol 121.6 62.2 47.6 0.06 1.50 1.34 Example 7 sol 111.3 65.9 50.5 0.04 1.54 1.41 Example 8 sol 114.4 64.6 39.7 0.04 1.44 1.47 Example 9 sol 125.4 64.4 41.6 0.03 1.51 1.37 Example 10 sol 123.7 63.2 54.9 0.04 1.64 1.47 Example 11 sol 111.8 64.4 44.5 0.03 1.64 1.43 Example 12 sol 127.6 67.8 49.6 0.04 1.55 1.32 Comparative nitrate 98.9 56.6 30.1 0.04 1.00 1.00 Example 1 Comparative nitrate 94.7 56.6 29.5 0.04 0.74 0.84 Example 2 Comparative nitrate 103.9 60.1 33.1 0.01 1.16 0.95 Example 3 Comparative sol 108.7 64.2 51.7 0 1.43 1.09 Example 4 Comparative nitrate 41.9 59.5 6.1 0.08 0.29 0.28 Example 5 Comparative nitrate 86.8 42.5 17.7 0.12 0.73 0.67 Example 6

(22) Comparative example 4, prepared using an alumina sol in a manner consistent with Examples 1-11 but without silica, has a high initial activity but an inferior retained activity.

(23) The aluminium nitrate-based products in Comparative Examples 1, 5 and 6 have inferior initial and retained activities. This remains so, even if the calcination conditions are adjusted in accordance with Example 1 (Comparative Example 2).

(24) Comparative example 3, prepared by separate co-precipitation of a silica-alumina co-precipitate using aluminium nitrate, also produced a catalyst with an inferior retention of activity.