Process for preparing cobalt catalysts on titania support
Catalysts comprising cobalt on a titania support are produced by mixing together particles of a solid titania support and an aqueous solution of cobalt ammine carbonate, and heating to an elevated temperature sufficient to effect decomposition of the cobalt ammine carbonate and precipitation of a cobalt species onto said support. The catalysts are useful in hydrogenation and Fischer-Tropsch reactions.
1. A process for manufacturing a catalyst which comprises a cobalt species on a titania support having upon reduction at 425° C., a cobalt metal surface area, as measured by hydrogen chemisorption at 150° C., in the range from 15 to 100 m 2 per gram total cobalt, comprising mixing together said titania support and an aqueous solution of cobalt ammine carbonate at a pH in the range 7.5 to 12, and then heating to a temperature in the range 60 to 110° C. to effect decomposition of the cobalt ammine carbonate and precipitation of an insoluble cobalt compound onto said titania support, wherein the pH is maintained above 7.5 during the heating step, further comprising directly reducing the cobalt compound without a calcining step.
2. A process according to claim 1 , comprising saturating a titania support with an aqueous solution of cobalt ammine carbonate, and removing the excess of the solution, before heating the resulting product to a temperature sufficient to effect decomposition of the cobalt ammine carbonate.
3. A process according to claim 1 , wherein the mixture of titania support and said cobalt solution is heated to a temperature sufficient to effect decomposition of the cobalt ammine carbonate in situ before separating the solid catalyst from the mixture and drying.
4. A process according to claim 3 further comprising filtering a solid material from the aqueous solution, drying the solid material, and directly reducing the cobalt compound without a calcining step.
5. A process according to claim 1 , wherein the titania support and cobalt solution are maintained at an elevated temperature for a period of at least 60 minutes.
6. A process according to claim 1 wherein the step of reducing the resulting catalyst product is performed with hydrogen at a temperature between 300 to 550° C.
7. A process according to in claim 6 , further comprising the step of dispersing the reduced catalyst product in particulate form in a carrier matrix.
8. A process according to claim 1 wherein the titania support and aqueous solution of cobalt ammine carbonate are mixed at a pH in the range 9 to 12.
9. A process for manufacturing a catalyst which comprises elemental cobalt on a titania support having, upon reduction at 425° C., a cobalt metal surface area, as measured by hydrogen chemisorption at 150° C., in the range from 15 to 100 m 2 per gram total cobalt, comprising mixing together said titania support and an aqueous solution of cobalt ammine carbonate at a pH in the range 9 to 12, then heating to a temperature in the range 60 to 110° C. to effect decomposition of the cobalt ammine carbonate and precipitation of an insoluble cobalt compound selected from at least one of basic cobalt carbonate species and cobalt oxides onto said titania support, filtering a solid material from the aqueous solution, wherein the pH is maintained above 7.5 during the heating step, drying the solid material, and directly reducing the cobalt compound without a calcining step.
10. A catalyst comprising a cobalt species on a titania support and having upon reduction at 425° C., a cobalt metal surface area, as measured by hydrogen chemisorption at 150° C., in the range from 15 to 100 m 2 per gram total cobalt, made by mixing together said titania support and an aqueous solution of cobalt ammine carbonate at a pH in the range 7.5 to 12, and then heating said mixed together titania support and aqueous solution of cobalt ammine carbonate to a temperature in the range 60 to 110° C. to effect decomposition of the cobalt ammine carbonate and precipitation of an insoluble cobalt compound onto said titania support, wherein the pH is maintained above 7.5 during the heating step, further comprising directly reducing the cobalt compound without a calcining step.
11. A catalyst according to claim 10 having a cobalt metal surface area in the range from 20 to 40 m 2 per gram total cobalt.
12. A catalyst according to claim 10 wherein the titania is a coating on a silica or alumina support.
13. A catalyst according to claim 12 wherein the titania coating is present as a coating of 0.5 to 5 monolayers of titania on the underlying support.
14. A catalyst comprising elemental cobalt on a titania support and having, upon reduction at 425° C., a cobalt metal surface area, as measured by hydrogen chemisorption at 150° C., in the range from 15 to 100 m 2 per gram total cobalt, made by mixing together said titania support and an aqueous solution of cobalt ammine carbonate at a pH in the range 9 to 12, and then heating said mixed together titania support and aqueous solution of cobalt ammine carbonate to a temperature in the range 60 to 110° C. to effect decomposition of the cobalt ammine carbonate and precipitation of an insoluble cobalt compound selected from basic cobalt carbonate species and/or cobalt oxides onto said titania support, wherein the pH is maintained above 7.5 during the heating step, filtering a solid material from the aqueous solution, drying the solid material, and directly reducing the cobalt compound without a calcining step.