Method for making copper-containing catalysts
A method for preparing a copper-containing catalyst is described comprising the steps of: (a) combining an acidic copper-containing solution with a first basic precipitant solution in a first precipitation step to form a first precipitate, (b) combining an acidic aluminium-containing solution, further comprising one or more metal compounds selected from copper compounds, zinc compounds and promoter compounds, with a second basic precipitant solution in a second precipitation step to form a second precipitate, (c) contacting the first and second precipitates together in a further mixing step to form a catalyst precursor, and (d) washing, drying and calcining the catalyst precursor to form the copper-containing catalyst, wherein a silica precursor is included in the first precipitation step, the second precipitation step or the precipitate mixing step, to provide a catalyst with a silica content, expressed as S1O2, in the range of 0.1 to 5.0 wt %.
1. A method for preparing a copper-containing catalyst comprising the steps of: (a) combining an acidic copper-containing solution with a first basic precipitant solution in a first precipitation step to form a first precipitate, (b) combining an acidic aluminium-containing solution, further comprising one or more metal compounds selected from copper compounds, zinc compounds and promoter compounds, with a second basic precipitant solution in a second precipitation step to form a second precipitate, (c) contacting the first and second precipitates together in a further mixing step to form a catalyst precursor, and (d) washing, drying and calcining the catalyst precursor to form the copper-containing catalyst, wherein a silica precursor is included in the first precipitation step, the second precipitation step or the precipitate mixing step, to provide a catalyst with a silica content, expressed as SiO 2 , in the range of 0.1 to 5.0 wt %.
2. The method according to claim 1 , wherein the first precipitation step is performed by combining an aqueous acidic copper-containing solution containing copper and zinc compounds with an aqueous alkali metal carbonate solution in a first precipitation vessel.
3. The method according to claim 2 , wherein the copper and zinc compounds are nitrates and the alkali metal carbonate comprises sodium carbonate or potassium carbonate.
4. The method according to claim 1 , wherein copper compounds are included in both the first precipitation step and the second precipitation step and the amount of copper in the second precipitation step is in a range of 0.5 to 20 wt % of the total copper added.
5. The method according to claim 1 , wherein zinc compounds are included in both the first precipitation step and the second precipitation step and the amount of zinc in the second precipitation step in in a range of 0.5 to 50 wt % of the total zinc added.
6. The method according to claim 1 , wherein one or more promoter compounds selected from compounds of Mg, Co, Mn, V, Ti, Zr or rare earths, are included in the acidic copper-containing solution in the first precipitation step and/or the acidic aluminium-containing solution in the second precipitation step.
7. The method according to claim 1 , wherein the first precipitation step is performed at a temperature in a range of 40 to 80° C., and a pH range of 6-8.
8. The method according to claim 1 , wherein the second precipitation step is performed by combining an aqueous solution containing aluminium nitrate and one or more metal nitrates selected from copper nitrate, zinc nitrate and promoter metal nitrate with an aqueous alkali metal hydroxide solution.
9. The method according to claim 1 , wherein the second precipitation step is performed at a temperature in a range of 10 to 80° C., and at a pH in the range of 5-9.
10. The method according to claim 1 , wherein the second precipitate formed in step (b) and/or the combined precipitates in step (c) are aged at a temperature in a range of 10 to 80° C.
11. The method according to claim 1 , wherein step (a) is performed before or after step (b), or step (a) and step (b) are performed simultaneously.
12. The method according to claim 1 , wherein neither of the precipitates from steps (a) and (b) are separated and washed prior to the combining step (c).
13. The method according to claim 1 , wherein in step (c) slurries of the first and second precipitates are combined in a mixing vessel.
14. The method according to claim 1 , wherein step (c) is performed at the same time as step (a) or step (b).
15. The method according to claim 1 , wherein the catalyst has a silica content, expressed as SiO 2 , in a range of 0.1 to 3.0 wt %.
16. The method according to claim 1 , wherein the silica precursor is a colloidal silica or silica sol, a water-soluble silicon compound, an alkali metal silicate, or an organo-silicate.
17. The method according to claim 1 , wherein an acidic silica sol is included in the acidic copper-containing solution in the first precipitation step, the acidic aluminium-containing solution in the second precipitation step, the first precipitate, the second precipitate or a mixture of the first and second precipitates in the precipitate mixing step.
18. The method according to claim 1 , wherein an alkali metal silicate or a basic silica sol is included in the first basic precipitant solution in the first precipitation step, the second basic precipitant solution in the second precipitation step, the first precipitate, the second precipitate or to a mixture of the first and second precipitates in the precipitate mixing step.
19. The method according to claim 1 wherein the drying is performed at a temperature in he a range of 90-150° C.
20. The method according to claim 1 wherein the calcination is performed at a temperature in a range of 250° C. to 500° C.
21. The method according to claim 1 wherein the dried or calcined catalyst precursor is shaped by pelleting.
22. The method according to claim 1 , wherein one or more zinc compounds are included in the first precipitation step and the second precipitation step, and the weight ratio of Cu:Zn (expressed as CuO:ZnO) in the copper-containing catalyst is in a range of 2:1 to 3.5:1 for methanol synthesis catalysts, and in a range of 1.4:1 to 2.0:1 for water-gas shift catalysts.
23. The method according to claim 1 , wherein the copper-containing catalyst comprises 30-70% by weight of copper, expressed as CuO, 15 to 50% by weight of Zn, expressed as ZnO, 5 to 40% by weight alumina, expressed as Al 2 O 3 , 0 to 5% by weight magnesia, expressed as MgO, and 0.1 to 2.0% by weight Si, expressed as SiO 2 .
24. The method according to claim 1 , wherein the copper-containing catalyst comprises 50 to 68% by weight of copper, expressed as CuO, 20 to 35% by weight of Zn, expressed as ZnO, 6 to 20% by weight alumina, expressed as Al 2 O 3 , 0 to 5% by weight magnesia, expressed as MgO, and 0.20 to 1.0% by weight Si, expressed as SiO 2 .
25. A catalyst obtainable by the method of claim 1 .
26. A process comprising contacting a methanol synthesis feedstock a methanol reforming feedstock, or a water-gas shift feedstock with the catalyst of claim 25 .
27. The method according to claim 1 , wherein the catalyst has a silica content, expressed as SiO 2 , in a range of 0.1 to 2.0 wt %.
28. The method according to claim 1 , wherein the catalyst has a silica content, expressed as SiO 2 , in a range of 0.2 to 1.0 wt %.