Experimental and computational investigations of sulfur-resistant bimetallic catalysts for reforming of biomass gasification products

Density functional theory calculations were used to screen ethylene and sulfur adsorption energies of model Ni bimetallic surfaces. These calculations were used to successfully identify Ni-based sulfur-resistant ethylene reforming catalysts. NiRu catalysts were found to exhibit improved activity, both in the presence and in the absence of sulfur, compared with pure Ni both for ethylene reforming and for the reforming of tars in biomass-derived synthesis gas. [Display omitted] ► Density functional studies of ethylene and sulfur adsorption on bimetallics with Ni. ► Experimental studies of simulated tar reforming on supported bimetallic catalysts. ► NiRu catalysts exhibit improved sulfur-resistant reforming activity. A combination of density functional theory (DFT) calculations and experimental studies of supported catalysts was used to identify H 2S-resistant biomass gasification product reforming catalysts. DFT calculations were used to search for bimetallic, nickel-based (1 1 1) surfaces with lower sulfur adsorption energies and enhanced ethylene adsorption energies. These metrics were used as predictors for H 2S resistance and activity toward steam reforming of ethylene, respectively. Relative to Ni, DFT studies found that the Ni/Sn surface alloy exhibited enhanced sulfur resistance and the Ni/Ru system exhibited an improved ethylene binding energy with a small increase in sulfur binding energy. A series of supported bimetallic nickel catalysts was prepared and screened under model ethylene reforming conditions and simulated biomass tar reforming conditions. The observed experimental trends in activity were consistent with theoretical predictions, with observed reforming activities in the order Ni/Ru > Ni > Ni/Sn. Interestingly, Ni/Ru showed a high level of resistance to sulfur poisoning compared with Ni. This sulfur resistance can be partly explained by trends in sulfur versus ethylene binding energy at different types of sites across the bimetallic surface.