Catalytic Steam Reforming of Benzene as a Bio-tar Model Compound over Ni–Fe/TiO2 Catalysts

Abstract

Bio-tar formed during biomass gasification can cause the blockage or corrosion of pipelines and devices. Catalytic reforming through Ni-based catalysts is a potential method to achieve tar elimination, while carbon deposition is the main obstacle. In this study, the steam reforming of benzene was investigated over modified Ni/TiO2 catalysts, and the effects of metal promoters, reaction temperatures, and steam-to-carbon (S/C) molar ratios were explored. The results indicated that the Fe promoter was promising to simultaneously achieve the H2-rich gas production and suppress the carbon deposition over the catalyst. When the reaction temperature was 800 °C and the S/C molar ratio was 1.00, the benzene conversion ratio and the H2 yield, respectively, reached 96.31% and 102.53 mmol/gbenzene. Ni–Fe alloys were generated after the modification with the Fe promoter, which improved the dispersion of Ni components. Besides, the adsorption of H2O molecules was enhanced which favored the formation of lattice oxygen and accelerated the reforming of benzene. Furthermore, the accumulation of lattice oxygen promoted the oxidation of amorphous carbon and suppressed the formation of graphitic carbon, thereby protecting the active Ni sites from the coverage of the carbon layer. Therefore, the resistance of carbon deposition of the Fe-modified Ni/TiO2 catalyst was improved.