Perovskite Adsorbents for Warm-Gas Removal of Sulfur

Technology is needed to remove impurities, especially sulfur, from the hydrogen produced from coal-derived synthesis gas. Although oxides of zinc now remove sulfur from industrial gas streams to the part-per-million level in the presence of steam, much greater removal effectiveness will be required for the hydrogen product. In fact, concentrations of sulfur in the part per billion level are required to prevent poisoning of fuel-cell catalysts, membranes, and catalysts used to produce synthetic fuels. Thermodynamic analysis indicates that sorbents incorporating cerium and lanthanum will reduce sulfur from the part-per-million to below the part-per-billion level, even in the presence of steam. In Phase I, measurements of the performance of sorbents incorporating both cerium and lanthanum showed excellent bulk uptake of sulfur, as predicted. In Phase II, the sorbents will be optimized for maximum sulfur uptake, for regeneration, and for attrition resistance. A techno-economic analysis will determine a cost-effective route for scale-up and integration with zinc-based sorbents and hydrogen purification membranes. Commercial Applications and Other Benefits as described by the awardee: Removing sulfur and other impurities from coal-derived hydrogen should speed the commercialization of pollution-free coal-fired power plants. The technology also should benefit sequestration of carbon dioxide, operation of fuel cells, production of synthetic fuels, and long-term operation of hydrogen-powered turbines.