Available Technology

Catalysts for Reduction of SO2 to Elemental Sulfur IB-968

Oil refineries, coal-based power plants, smelters, and geothermal energy production plants generate sulfur acid gases, H2S and/or SO2. These acid gases must be treated because they are not permitted for release to the atmosphere. Currently, the most commonly used treatment method involves the modified Claus process to convert these acid gases to elemental sulfur; however, due to the thermodynamic equilibrium limitation of the Claus reaction, typical overall sulfur recovery ranges from 72-74%, 93-95%, and 95-97% for 1-stage Claus, 2-stage Claus, and 3-stage Claus plants, respectively. Ted Chang, Yun Jin, Qi-Quan Yu at Lawrence Berkeley National Laboratory (LBNL) have developed a technique for the treatment of SO2 and H2S. This technique uses a catalyst for the reduction of SO2 by H2S, H2, CO, and/or synthesis gas to elemental sulfur. Using 1-stage reactor, this catalyst is capable of achieving as much as 97% sulfur recovery from gas streams containing low SO2 concentration (Claus plants), medium SO2 concentration (IGCC plants), as well as high SO2 concentration (regenerative SO2 scrubbers). The catalyst is composed of a mixture of common transition metal sulfides on alumina, and it is inexpensive to manufacture.
High conversion rate: High SO2 converstion to elemental sulfur can be obtained on 1st stage Claus head gas, 1st stage Claus tail gas, 2nd stage Claus tail gas, IGCC hot gas, and pure SO2 gas with only 1-stage reactor. - Capable of converting SO2 and H2S to elemental sulfur with efficiency more than that predicted by Claus equilibrium. - Single-stage reactor: Only one single-stage reactor is required to obtain a high yield of elemental sulfur. - Achieved as much as 97% conversion rates in laboratory experiments. - Inexpensive catalyst: Common transition metal sulfides.
Internal Laboratory Ref #: 
IB- 968, IB-1176
Patent Status: 
Available for licensing - U.S. Patents #5,494,879 & 6,297,189
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