Effect of boron doping on the performance of Ni/Biochar catalysts for steam reforming of toluene as a tar model compound

Biochar-supported nickel (Ni/BC) catalysts have potential applications in steam reforming of tar during biomass gasification. However, the industrial application of Ni/BC catalysts is restricted by their rapid deactivation caused by the gasification of biochar support and deposition of carbon on the active Ni metal. In this study, the effect of boron doping was explored on the performance of Ni/BC catalysts in steam reforming of toluene as a tar model compound. A series of Ni/BC and boron-doped Ni/BC catalysts were prepared by impregnating Ni salts on raw and acid-washed biomass as the starting materials and used in steam reforming of toluene as the tar model compound. It was found that boron doping significantly prolonged the lifetime of Ni/BC catalysts by interacting with Ni and the biochar support simultaneously. It is believed that boron doping lowered the gasification consumption rate of the biochar support in three ways: transforming the inherent K into more stable borates, inhibiting the desorption of CO and CO2, and forming B2O3 as the active site blocker. Furthermore, boron doping also reduced coke deposition on the Ni particles.