Catalyst for the oxidation of sulfur compounds
In a broad form the present invention relates to a method for oxidation of a species comprising sulfur in an oxidation state below +4, such as H 2 S, CS 2 , COS and S 8 vapor, to SO 2 said method comprising the step of contacting the gas and an oxidant with a catalytically active material consisting of one or more elements taken from the group consisting of V, W, Ce, Mo, Fe, Ca, Mg, Si, Ti and Al in elemental, oxide, carbide or sulfide form, optionally with the presence of other elements in a concentration below 1 wt %, at a temperature between 180° C. and 290° C., 330° C., 360° C. or 450° C., with the associated benefit of such a temperature being highly energy effective, and the benefit of said elements having a low tendency to form sulfates under the conditions, with the related benefit of an increased stability of the catalytically active material. The other elements present may be catalytically active noble metals or impurities in the listed materials.
1. A method for the oxidation of a gas comprising one or more sulfur species having an oxidation state below +4, and selected from H 2 S, CS 2 , COS and S 8 vapor to SO 2 , said method comprising contacting the gas and an oxidant with a catalytically active material consisting of one or more metal oxides in which the metal is taken from the group consisting of V, W, Ce, Mo, Fe, Ca, and Mg, and one or more supports taken from the group consisting of Al 2 O 3 , SiO 2 , SiC and TiO 2 , and a stabilizing constituent comprising WO 3 , optionally in the presence of other elements in a concentration below 1 wt %, at a temperature between 180° C. and 450° C.
2. A method according to claim 1 in which said catalytically active material comprises from 1 wt % to 50 wt % V 2 O 5 .
3. A method according to claim 2 comprising above 2 wt % to 50 wt % V 2 O 5 .
4. A method according to claim 1 , in which the porous support comprises TiO 2 .
5. A method according to claim 1 , in which the support comprises SiO 2 as a diatomaceous earth or a highly porous artificial silica.
6. A method according to claim 1 , in which said stabilizing constituent comprises from 2 wt % to 50 wt %.
7. A method according to claim 1 , in which said catalytically active material comprises a monolithic catalyst substrate comprising one of metal, high silicon glass fibres, glass paper, cordierite and silicon carbide, and a catalyst layer.
8. A method according to claim 7 , wherein the monolithic catalyst has a void volume of from 65 vol to % 80 vol %.
9. A method according to claim 7 , wherein the catalyst layer has a thickness of 10-150 μm.
10. A method to claim 1 , in which said catalytically active material further comprises from 0.01 wt % to 1 wt % of a noble metal.
11. A method to claim 10 , in which said noble metal comprises from 0.05 wt % to 1 wt % of one of Pd and Pt.
12. A method according to claim 1 in which the oxidant is O 2 and is present in at least a stoichiometric amount for oxidation of said sulfur containing compounds to SO 2 .
13. A method for oxidation of a gas comprising one or more sulfur species selected from H 2 S, CS 2 , COS and/or S 8 vapor, comprising contacting the gas, an oxidant with a supported catalytically active material at a temperature from 180° C. to 450° C., said catalytically active material consisting of one or more oxides of a metal selected from the group consisting of V, W, Ce, Mo, Fe, Ca, and Mg, and one or more supports taken from the group consisting of Al 2 O 3 , SiO 2 , SiC and TiO 2 , said supported catalytically active material further including from 3 wt. % to 50 wt. % of a stabilizing constituent and, optionally less than 1 wt. % of other elements, to convert said sulfur species to SO 2 .