Fuel gas desulfurization at elevated temperatures with copper-based sorbents

Zinc-based sorbents, the leading candidates for hot gas cleanup, have been shown to suffer from zinc volatilization at elevated temperatures, leading to sorbent deterioration, increasing sorbent replacement costs. Copper-based sorbents, because of the high melting point of the metal, do not suffer from this problem. However, bulk copper oxide is generally reduced to metallic copper in reducing fuel gas environments leading to thermodynamic limitations, resulting in insufficient level of desulfurization. The reduction stability and therefore the desulfurization performance of copper oxide sorbents can be significantly improved by combining copper oxide with other oxides in a supported form or as bulk mixed metal oxides. This paper addresses the results of a systematic study of several novel copper-based sorbents for hot gas cleanup application. The evaluation criteria included reduction stability, sulfidation reactivity and regenerability at elevated temperatures. The performance of the most promising sorbent in long duration cycle sulfidation-regeneration tests is also presented.