Reforming catalyst
Process for the steam reforming of hydrocarbons comprising contacting a feed gas with a catalyst consisting of an active compound in the form of an alloy of nickel and one of iridium, rhodium and ruthenium, on a support comprising alumina, zirconia, magnesia, titania, or combinations thereof.
1. Process for the steam reforming of hydrocarbons comprising
contacting a feed gas in a catalytic partial oxidation (CPO) reactor or autothermal reformer operating at temperatures in the range 800-1600° C. and pressures of 20-100 bar with an egg-shell catalyst consisting of an active compound in the form of an alloy of nickel and one of iridium and ruthenium, on a support comprising alumina, zirconia, magnesia, titania or combinations thereof, wherein the catalyst is cylindrically shaped and has one or more through holes, where the distance from the center to the external surface of the catalyst is 10 to 40 mm, the height of the catalyst is 10 to 40 mm and the diameter of the one or more through holes is 3 to 30 mm, and wherein the support comprising alumina is selected from α-alumina, calcium aluminate, magnesium-aluminum spinel and combinations thereof, wherein at least 90 wt % of the iridium or ruthenium in the catalyst is located in an outer shell having a depth of up to 10% from the external surface of the catalyst or up to 10% from the periphery of the one or more through holes of the catalyst.
2. Process according to claim 1 , in which the catalyst is provided in one or more catalyst layers with a void/(external- or geometrical surface area)-ratio of 1.0-4.5 L/m 2 .
3. Process according to claim 2 , in which the top layer is of a first type of catalyst with a void/(external or geometrical surface area)-ratio which is above 3 L/m 2 and below 4.5 L/m 2 , and at least a second layer is of a second type of catalyst with a void/(external or geometrical surface area)-ratio which is below 3 L/m 2 and above 1.0 L/m 2 .
4. Process according to claim 2 , wherein the void/(external- or geometrical surface area)-ratio of the second type of catalyst is above 2 L/m 2 and below 4.5 L/m 2 .
5. Process according to claim 2 , comprising at least a further third layer of a third type of catalyst having void/(external or geometrical surface area)-ratio in the range 1.0-4.5.
6. Process according to claim 1 , in which the active compound is an alloy of nickel and iridium, or an alloy of nickel and ruthenium, wherein the content of iridium or ruthenium in the catalyst is in the range 0.01 to 0.5 wt % and the nickel content in the catalyst is 2 to 16 wt %.
7. Process according to claim 1 , in which the concentration of iridium or ruthenium in the outer shell is 0.1 to 5.0 wt %.
8. Process according to claim 1 , wherein the active compound in the catalyst in the form of an alloy of nickel and one of iridium and ruthenium has average crystallite size of below 0.1 μm when measured as aged or spent catalyst.
9. Process according to claim 1 , in which the catalyst is prepared by first providing nickel into the support and in a later step adding iridium or ruthenium.
10. Process according to claim 9 , in which the catalyst is prepared by impregnating a catalyst consisting of nickel on a support with an aqueous solution of iridium or ruthenium, then calcining in air at 400-600° C. and reducing in H 2 at 350-600° C.
11. Process according to claim 10 , wherein the impregnation of the catalyst is conducted with an aqueous solution of IrCl 3 :H 2 O or iridium acetate or Ru(NO 3 ) 3 NO and the support comprises alumina selected from α-alumina and magnesium-aluminium spinel.
12. Process according to claim 1 further comprising withdrawing from the catalytic partial oxidation (CPO) reactor or autothermal reformer a synthesis gas for downstream Fischer-Tropsch synthesis, ammonia synthesis, methanol synthesis and dimethyl ether (DME) synthesis.