Catalyst preparation method
A method is described for preparing a catalyst including the steps of: (i) impregnating a calcined support comprising a metal aluminate with a solution of nickel acetate at a temperature ≧40° C. and drying the impregnated support, (ii) calcining the dried impregnated support, to form nickel oxide on the surface of the support and (iii) optionally repeating steps (i) and (ii) on the nickel oxide coated support. The method provides an eggshell catalyst in which the metal oxide is concentrated in an outer layer on the support.
1. A method for preparing a catalyst comprising the steps of:
(i) impregnating a calcined support comprising a metal aluminate with a solution comprising nickel acetate at a temperature ≧40° C. to form an impregnated support and drying the impregnated support to form a dried impregnated support,
(ii) calcining the dried impregnated support, to form an eggshell catalyst comprising a nickel oxide coated support, and
(iii) optionally repeating steps (i) and (ii), on the nickel oxide coated support.
2. A method according to claim 1 wherein the metal aluminate is selected from the group consisting of calcium aluminate, magnesium aluminate and nickel aluminate.
3. A method according to claim 1 wherein the metal aluminate is calcium aluminate and the calcined support is formed by shaping a calcium aluminate cement powder into a shaped support, curing the cement, and subsequently calcining the shaped support.
4. A method according to claim 3 wherein the shaped support is alkalised by impregnation with a solution of an alkali prior to calcining the shaped support.
5. A method according to claim 1 wherein the calcined support is in the form of a shaped pellet, extrudate, or granule.
6. A method according to claim 5 wherein the calcined support is in the form of a cylindrical pellet having between 1 and 12 holes extending therethrough.
7. A method according to claim 1 wherein the solution is at a temperature ≧50° C.
8. A method according to claim 1 wherein the solution has a Ni concentration in the range of 0.5-1.0M.
9. A method according to claim 1 wherein steps (i) and (ii) are performed until the nickel oxide coated support has a nickel oxide content in the range of 2 to 25% wt.
10. A method according to claim 1 wherein one or more promoter compounds are impregnated into the dried impregnated support and/or the nickel oxide coated support.
11. A method according to claim 1 wherein calcining the dried impregnated support is performed at a temperature in the range of 250-850° C.
12. A method according to claim 1 , further comprising the step of reducing nickel oxide on the nickel oxide coated support to elemental form with a hydrogen-containing gas mixture.
13. A method according to claim 1 wherein the metal aluminate is calcium aluminate and the calcined support is formed by shaping a calcium aluminate cement powder, with additional alumina and/or lime, into a shaped support, curing the cement, and subsequently calcining the shaped support.
14. A method according to claim 1 wherein the solution is at a temperature ≧60° C.
15. A method according to claim 1 wherein the solution Is at a temperature ≧70° C.