Patent ID: 8709366

Claim:
A method of treating an acid gas, comprising: providing from an off-gas source an oxygen-containing acid gas comprising sulfur dioxide, wherein the off-gas source is selected from the group consisting of a catalyst regenerator, a fluid catalytic cracking (FCC) unit, a coking unit, a smelter furnace and a power plant furnace; using hydrogen sulfide in a first portion of a recycle gas to catalytically react oxygen in the oxygen-containing acid gas comprising sulfur dioxide to form an oxygen-depleted gas comprising the sulfur dioxide and hydrogen sulfide; catalytically reacting a first portion of the oxygen-depleted gas comprising sulfur dioxide and hydrogen sulfide in a Claus reaction with a second portion of the recycle gas to form a treated gas and elemental sulfur; and catalytically reacting a second portion of the oxygen depleted gas comprising sulfur dioxide and hydrogen sulfide with a reducing gas to thereby form the recycle gas.