Sulfur removal from coal‐derived syngas: thermodynamic considerations and review

Abstract

AbstractCurrent research into desulfurization sorbents for coal gasification is aimed at maximizing sorption capacity, kinetics and attrition resistance, while minimizing cost and volatility. Isolating the chemical aspects of desulfurization sorbent performance, however, is difficult because sorption performance is highly dependent on the physical form of the sorbent. To guide sorbent development, thermodynamic calculations offer a consistent basis from which to compare various aspects of sorbent performance, which includes conversion, but also speciation, volatility and regeneration. This approach has been used to compare 24 potential sorbents for the removal of sulfur from syngas, including oxides of transition metals, alkaline earths, alkalis and borates. Oxides of copper, manganese and zinc are most favourable for high‐temperature sulfur sorption and these oxides are chemically regenerable. The thermodynamic calculations are confirmed by the available literature, with the ZnO, MnO and CuO receiving the most attention in recent years. Each oxide has characteristic disadvantages, such as the tendency of copper oxide to reduce, the high volatility of zinc oxide and the high regeneration temperature of manganese oxide. This is driving the development of fabrication techniques which maximize sorbent dispersion, stability and tolerance to repeated sulfidation/regeneration cycles. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd.