A Novel Cyclic Reaction System Involving CaS and CaSO₄ for Converting Sulfur Dioxide to Elemental Sulfur without Generating Secondary Pollutants. 1. Determination of Process Feasibility

Abstract

A new process for converting SO 2 to elemental sulfur by a cyclic process involving CaS and CaSO 4 has been developed. In this process, the raw material CaSO 4 is reduced to produce CaS, which is used to reduce SO 2 to elemental sulfur and produce CaSO 4 . The latter is then reduced to regenerate CaS. Experimentally, about 75% of CaS powder was converted to CaSO 4 in 20 min at 1153 K under 25.8 kPa of SO 2 partial pressure. About 95% of nickel-catalyzed CaSO 4 powder was reduced to CaS in 20 min at 1123 K under 86.1 kPa of hydrogen partial pressure. The reactivities of the powders remained relatively unchanged after 10 cycles of reactions and regenerations. Sulfur dioxide containing streams from certain sources contain higher partial pressures of SO 2, in which case the SO 2 −CaS reaction will be proportionally faster than that reported here. Detailed kinetics of the two-component reactions are described in the accompanying parts of this series.