Method for recovering hydrogen from hydrogen sulfide
The present invention provides a method for recovering hydrogen from hydrogen sulfide using a supported silver catalyst, and a method for purifying a gas stream containing hydrogen sulfide using such a catalyst.
1. A method for recovering hydrogen from hydrogen sulfide, said method comprising the steps of:
a. reacting hydrogen sulfide with supported silver at a temperature of at least 200° C., whereby the silver is converted to silver sulfide and hydrogen is released; and
b. subjecting the silver sulfide to mild oxidation carried out using gaseous oxygen at a temperature below 450° C., whereby the silver sulfide is converted to silver and sulfur dioxide.
2. A method for purifying a gas stream containing hydrogen sulfide, said method comprising the steps of:
passing said gas stream over a bed of supported silver at a temperature of at least 200° C., so that the hydrogen sulfide in the gas stream reacts with said silver, whereby the silver is converted to silver sulfide and hydrogen is released; and
subjecting the silver sulfide to mild oxidation carried out using gaseous oxygen at a temperature below 450° C., whereby the silver sulfide is converted to silver and sulfur dioxide.
3. The method according to claim 1 , wherein the silver content of the supported silver is 5-10 wt %.
4. The method according to claim 1 , wherein the support material has a surface area between 1-200 m 2 /g and/or a porosity from 0.2-0.5 cm 3 /g.
5. The method according to claim 1 , wherein the support material has a particle size of between 1-10 mm in diameter.
6. The method according to claim 1 , wherein mild oxidation is carried out using atmospheric air dilute in oxygen.
7. The method according to claim 1 , wherein step b. takes place at a temperature between 200 and 400° C.
8. The method according to claim 1 , wherein the method takes place during gasification of hydrocarbon fuels to synthesis gas.
9. The method according to claim 1 , wherein steps a and b take place immediately after one another in a continuous process.
10. The method according to claim 1 , wherein step a. occurs at a temperature of between 250-500° C.
11. The method according to claim 1 , wherein step a. occurs at a temperature of between 300-450° C.
12. The method according to claim 6 , wherein the atmospheric air dilute in oxygen is 0.5-5% vol.