Method and catalyst for direct sulphur oxidation of H2S contained in a gas

A process for oxidizing H2S contained in low concentration in a gas directly to sulphur comprising:

• combining the H2S-containing gas with a gas containing free oxygen in an amount to form an O2/H2S-containing gas with an O2/H2S molar ratio ranging from 0.05 to 15;
• contacting the O2/H2S-containing gas with a catalyst for the selective oxidation of H2S to sulphur, wherein the catalyst comprises a catalytically active phase containing at least one oxysulphide of at least one metal selected from the group consisting of nickel, iron, cobalt, copper, chromium, molybdenum and tungsten combined with a silicon carbide support at temperatures below the dew point of the sulphur formed by oxidation of H2S and depositing the sulphur on the catalyst;
• periodically regenerating by flushing the sulphur-laden catalyst using a non-oxidizing gas at temperatures of between 200° C. and 500° C. to vaporize sulphur retained on the catalyst;
• cooling the regenerated catalyst below the dew point of the sulphur to a temperature for H2S oxidation to be carried out again, such cooling being carried out by a gas having a temperature less than 180° C.;
• and
• contacting the regenerated catalyst at temperatures of less than 250° C. and for a time of between 0.2 and 3 hours, with an oxygenated gas stream consisting of an inert carrier gas containing 0.1% to 3% oxygen and 0% to 50% water by volume, to restore the metal oxysulphide phase of the catalyst.

A regenerative process for directly oxidizing to sulphur H2S contained in low concentration in a gas also containing 10% to 50% water by volume, a fraction of this water being in condensed form and forming with the gas a gas/condensed water mixed phrase, comprising:

• combining the H2S-containing mixed phase with a gas containing free oxygen in an amount to form an O2/H2S-containing mixed phase with an O2/H2S molar ratio ranging from 0.05 to 15;
• contacting the O2/H2S-containing mixed phase with a catalyst for the selective oxidation of H2S to sulphur disposed in an oxidation zone, wherein the catalyst comprises a catalytically active phase containing at least one oxysulphide of at least one metal selected from the group consisting of nickel, iron, cobalt, copper, chromium, molybdenum and tungsten combined with a silicon carbide support, at a temperature of between 35° C. and 70° C. and depositing the sulphur on the catalyst;
• maintaining the oxidation zone at the temperature of between 35° C. and 70° C. by injecting into the zone a stream of cooled water circulating continuously;
• periodically regenerating by flushing the sulphur-laden catalyst using a non-oxidizing gas at temperature of between 200° C. and 500° C. to vaporize sulphur retained on the catalyst;
• and
• cooling the regenerated catalyst below the dew point of the sulphur to a temperature for the H2S oxidation to be carried out again, such cooling being carried out by a gas having a temperature less than 180° C.