Regenerative Adsorption and Removal of H 2 S from Hot Fuel Gas Streams by Rare Earth Oxides

Abstract

Sorbent materials that allow for high-temperature, regenerative desulfurization of fuel gas streams for the anode of a solid oxide fuel cell have been developed. Reversible adsorption of H 2 S on cerium and lanthanum oxide surfaces is demonstrated over many cycles at temperatures as high as 800°C, on both fresh or presulfided sorbents, and at very high space velocities. The adsorption and desorption processes are very fast, and removal of H 2 S to sub–parts per million levels is achieved at very short (millisecond) contact times. Any type of sulfur-free gas, including water vapor, can be used to regenerate the sorbent surface. Preferably, the anode off-gas stream is used to sweep the desorbed H 2 S to a burner.