PNNL

Abstract

This study presents a combined experimental and theoretical investigation into the steam reforming of biomass gasifier-derived syngas over MgAl2O4-supported transition metals (Ni, Rh, Ir, Ru, Pt, and Pd) and bimetallic IrNi catalysts. Using a model syngas consisting of H2, CO, CO2, CH4, C2H4, and H2O, Ir and Rh catalysts are found to be more stable than Ru, Pt, and Pd catalysts (at 850°C, 1 bar, 114,000 h-1). When benzene and naphthalene are added to the feed (as a tar simulant) stability is affected by both tar concentration and type of tar present in the feed. For example, deactivation is relatively unchanged when a relatively high concentration of benzene (i.e., 0.34 mol%) is added to the feed; however, deactivation is significantly pronounced with the addition of only 0.08 mol% naphthalene. Catalytic deactivation, caused primarily by carbon formation from tar, can be minimized by operating at a high reaction temperature (e.g., 850°C). In addition, promoting Ni with Ir significantly enhances stability. By using bimetallic formulations of Ir and Ni (0.5%