A new generation of water gas shift catalysts for fuel cell applications

摘要

The generation of high-purity hydrogen from hydrocarbon fuels for fuel cell applications is essential for efficient operation of the solid polymer electrolyte (PEM) fuel cell. In general, most feasible strategies to generate hydrogen from hydrocarbon fuels consist of a reforming step to generate a mixture of H_2, CO, CO_2 and H_2O (steam) followed by water gas shift (WGS) and CO clean-up steps. The WGS reaction is industrially carried out using two particulate catalysts―FeCr and CuZn―at temperatures between 350-500 and 180-250℃, respectively. Both catalysts are pyrophoric: they spontaneously generate heat to dangerously high temperatures when exposed to air after activation. In addition, CuZn needs to be carefully activated before use. We have developed a base metal non-pyrophoric alternative to commercial CuZn. The catalyst, referred to as Selectra Shift, activates in process gas, has stable activity under a wide variety of process conditions and is safer if accidentally exposed to air. It therefore represents a safer alternative to the commercial CuZn for fuel cell applications. In addition, Engelhard has developed base metal and precious metal monolith WGS catalysts for applications where the catalyst must be optimized for small reactor volumes, lower pressure drop and mechanical integrity. Inhibitors are added to the precious metal catalyst to suppress the undesirable methanation side reaction.