Selective catalytic reduction of sulfur dioxide to elemental sulfur. Quarterly technical progress report No. 4, April--June 1993

Elemental sulfur recovery from SO{sub 2}-containing gas stream is highly attractive as it produces a salable product and no waste to dispose of. However, commercially available schemes are complex and involve multi-stage reactors, such as, most notably in the Resox (reduction of SO{sub 2} with coke) and Claus plant(reaction of SO{sub 2} with H{sub 2}S over catalyst). This project will investigate a cerium oxide catalyst for the single stage selective reduction of SO{sub 2} to elemental sulfur by a reductant, such as carbon monoxide. Cerium oxide has been identified in recent work at MIT as a superior catalyst for SO{sub 2} reduction by CO to elemental sulfur because its high activity and high selectivity to sulfur over COS over a wide temperature range(400--650{degrees}C). The detailed kinetic and parametric studies of SO{sub 2} reduction planned in this work over various CeO{sub 2}-formulations will provide the necessary basis for development of a very simplified process, namely that of a single-stage elemental sulfur recovery scheme from variable concentration gas streams, The potential cost- and energy-efficiency benefits from this approach can not be overstated. A first apparent application is treatment of a regenerator off-gases in power plants using regenerative flue gas desulfurization. Such a simple catalytic converter may offer the long-sought ``Claus-alternative`` for coal-fired power plant applications.