LaCoO3 is a promising catalyst for the dry reforming of benzene used as a surrogate of biomass tar.

Abstract

Tar build-up is one of the bottlenecks of biomass gasification processes. Dry reforming of tar is an alternative solution if the oxygen chemical potential on the catalyst surface is at a sufficient level. For this purpose, an oxygen-donor perovskite, LaCoO₃, was used as a catalyst for the dry reforming of tar. To circumvent the complexity of the tar and its constituents, the benzene molecule was chosen as a model compound. Dry reforming of benzene vapor on the LaCoO₃ catalyst was investigated at temperatures of 600, 700, and 800 °C; at CO₂/C₆H₆ ratios of 3, 6, and 12; and at space velocities of 14,000 and 28,000 h^-1. The conventional Ni(15 wt.%)/Al₂O₃ catalyst was also used as a reference material to determine the relative activity of the LaCoO₃ catalyst. Different characterization techniques such as X-ray diffraction, N₂ adsorption-desorption, temperature-programmed reduction, and oxidation were used to determine the physicochemical characteristics of the catalysts. The findings demonstrated that the LaCoO₃ catalyst has higher CO₂ conversion, higher H₂ and CO yields, and better stability than the Ni(15 wt.%)/γ-Al₂O₃ catalyst. The improvement in activity was attributed to the strong capacity of LaCoO₃ for oxygen exchange. The transfer of lattice oxygen from the surface of the LaCoO₃ catalyst facilitates the oxidation of carbon and other surface species and leads to higher conversion and yields.