Patent EA-001118-B1 (EA)
Title: Method and catalyst for direct sulphur oxidation of h2s contained in gas
Inventor: LEDOUX MARC
IPC: B01J27/04
Filed: 1998-12-24
Abstract: 1. A regenerative method for direct sulphur oxidation by catalytic H2S contained in low concentration in gas, providing contacting said gas, containing H2S with gas containing free oxygen in an amount enabling to provide a molar ratio O2 : H2S in a range between 0.05 to 15 with catalyst of selective oxidation H2S in sulphur , which is formed by a catalitically active phase associated with a silicon carbide support and consisting of at least one transitional metal, operating at temperatures lower than the dew point of the sulphur formed by oxidation of H2S which is deposited on the catalyst, then the oxidation catalyst filled with sulphur is periodically subjected to the regeneration by blowing using non oxidant gas operating at temperatures between 200 degree C and 500 degree C for sulphur evaporation retained on the catalyst and the regenerated catalyst is cooled to the temperature of the dew point of the sulphur required for a new oxidation of H2S realising the cooling by gas having the temperature below 180 degree C, characterized in that the active phase of catalyst contains at least one oxysilfide of at least one metal selected from nickel, iron, cobalt, copper, chromium, molybdenum, and tungsten. 2. A method according to claim 1, characterized in that the reaction of oxidation H2S into sulphur is carried out at temperatures from 30 degree C to 180 degree C. 3. A method according to claim 1, characterized in that the reaction of oxidation H2S into sulphur is carried out at temperatures from 35 degree C to 70 degree C and in particular from 40 degree C to 65 degree C. 4. A method according to claim 1, characterized in that the gas containing H2S is brought into contact with the oxidation catalyst at a temperature from 35 degree C to 70 degree C and, in particular, from 40 degree C to 65 degree C, wherein said temperature is lower or equal to the temperature selected for reaction  of H2S into sulphur. 5. A method of any preceding claim, characterized in that the regenerated catalyst is then brought into contact at a temperature below 250 degree C during period of time from 0.2 hr to 3 hrs with oxygen-containing gas flux formed by inert gas-support containing by volume from 0.1% to 3% of oxygen and from 0% to 50% of water to restore the phase of metal oxysilfide of the catalyst. 6. A method of any preceding claim, characterized in that the active phase associated with a silicon carbide support for forming the oxidation catalyst consists of at least one oxysilfide of a transition metal, selected from nickel, cobalt, iron and copper. 7. A method of any preceding claim, characterized in that the support from a silicon carbide of the oxidation catalyst constitutes at least 40% and, more particular, at least 50% of the mass of said catalyst. 8. A method of any preceding claim, characterized in that the active phase of the catalyst oxidation per mass of metal constitutes from 0.1% to 20%, more particular, from 0.2% to 15%, more particular from 0.2% to 7% of the catalyst mass. 9. A method of any preceding claim, characterized in that the specific surface of the catalyst determined by the BET method of the nitrogen adsorption takes values from 0.1 m<2>/g to 600 m<2>/g. 10. A method of any preceding claim, characterized in that the gas, containing free oxygen, is used in quantity able to secure the molar ratio O2 : H2S changing from 0.1 to 10 and, more particular, from 0.1 to 4. 11. A method of any preceding claim, characterized in that the time of contact of gaseous reaction medium with the oxidation catalyst under normal conditions of pressure and temperature is from 0.5 sec. to 20 sec. and, preferably from 1 sec. to 12 sec. 12. A method of any preceding claim, characterized in that the regeneration of the oxidation catalyst filled with sulphur is carried out at temperatures from 230 degree C to 450 degree C. 13. A method of any preceding claim, characterized in that H2S content in being treated gas is from 0.001% of volume to 25% of volume and more particular, from 0.01% to 20% of volume. 14. A method according to claim 3, characterized in that the treated gas has a temperature above 70 degree C and contains from 10% to 50% of water volume, wherein said gas prior to the contact oxidation catalyst H2S into sulphur is cooled to the temperature from 35 degree C to 70 degree C and, more particular, from 40 degree C to 65 degree C selected for oxidation, wherein a part of this water is condensed during said cooling and it is separated or not from the cooled treated gas before contacting the latter with the H2S oxidation catalyst. 15. A method according to claim 14, characterized in that the cooling of the being treated gas is carried out so that the water vapour content in the cooled gas is less by 10% of the volume, wherein the condensed water is separated from the cooled gas prior to contacting the latter with the H2S oxidation catalyst. 16. A method according to claim 14, characterized in that the water condensed during cooling of the being treated gas is not separated from the cooled gas and the mixed phase gas/condensed water is brought into contact with the H2S oxidation catalyst, maintain the temperature in the oxidation zone between 35 degree C to 70 degree C and, more particular, from 40 degree C to 65 degree C by injecting into said zone cooling water current, continuously circulating in a counter-current with the being treated gas, from the upper oxidation zone the purified gas is removed substantially freed from sulphur-containing compounds, and from the bottom oxidation zone the water stream is removed filled solid particles of sulphur, and resycle part of said water stream after the sulphur separation, which it contains, and cooling to form the cooling water stream to be injected into the oxidation zone. 17. A method according to claim 14, characterized in that the water condensed during cooling of the being treated gas, is not separated from the cooled gas and a mixed phase gas/condensed water is brought in contact with H2S oxidation catalyst, maintain the temperature in the oxidation zone between 35 degree C to 70 degree C and, more particular, from 40 degree C to 65 degree C by injecting into said zone cooling water current, continuously circulating in a cocurrent with the being treated gas, from the bottom oxidation zone a mixture purified gas/ condensed water filled with sulphur solid particles is removed, separate said mixture into the purified gas flux, which is removed, and aqueous phase and recycle part of said aqueous phase after the sulphur separation, which it contains, and cooling to form the cooling water stream to be injected into the oxidation zone. 18. A catalyst for direct selective catalytic oxidation H2S, formed by catalytically active phase associated with a silicon carbide support and consisting of a compound of at least one transition metal, wherein the support constitutes at least 40% and, more particular, at least 50% of mass of said catalyst, characterized in that its active phase is formed by at least one oxysulfide of at least one metal selected from nickel, iron, cobalt, copper, chromium, molybdenum, and tungsten. 19. A catalyst according to claim 18, characterized in that the active phase associated with the support consists of at least one oxysulfide of a transition metal selected from nickel, cobalt iron and copper. 20. A catalyst according to claim 18 or 19, characterized in that the active phase of the catalyst oxidation per mass of metal constitutes from 0.1% to 20%, more particular, from 0.2% to 15%, more particular from 0.2% to 7% of the catalyst mass. 21. A catalyst according to claim 18-20, characterized in that the specific surface of the catalyst determined by the BET method of the nitrogen adsorption takes values from 0.1 m<2>/g to 600 m<2>/g. 22. A regenerative method of direct oxidation into sulphur by catalytic oxidation H2S contained in a low concentration in gas, containing from 10% to 50% volume of water providing for contact of said gas, containing H2S, and gas, containing free oxygen, in quantity able to secure molar ratio O2 : H2S in interval from 0.05 to 15, with a catalyst of selective oxidation H2S in sulphur, for example, by a catalyst formed a catalytically active phase, associated with the support, in particular by the silicon carbide support and consisting of a compound of at least one transition metal, operating at temperatures lower than the dew point of the sulphur formed by H2S oxidation, which is deposited on the catalyst, then the oxidation catalyst, filled with sulphur, is periodically subjected to regeneration by blowing using non oxidant gas operating at temperatures between 200 degree C and 500 degree C for sulphur evaporation retained on the catalyst and the regenerated catalyst is cooled to the temperature of the dew point of the sulphur required for a new oxidation of H2S realising the cooling by gas having the temperature below 180 degree C, characterized in that the being treated gas is brought into contact with the oxidation catalyst at temperatures from 35 degree C to 70 degree C and, more preferably, from 40 degree C to 65 degree C, at which part of water, containing in gas, is in a condensed state and being treated gas is in the form of a mixed phase gas/condensed water, wherein the temperature in the oxidation zone is maintained from 35 degree C to 70 degree C and, more preferably, from 40 degree C to 65 degree C, by injecting into said zone a cooling water stream, continuously circulating in a counter-current or co-current with the being purified gas. 23. A method according to claim 22, characterized in that the being treated gas brought in contact with oxidation catalyst H2S circulates in a counter-current with a cooling water stream, injected into the oxidation zone, wherein from the upper oxidation zone the purified gas is removed substantially freed from sulphur-containing compounds, and from the bottom oxidation zone the