Abstract: A nickel catalyst supported on palygorskite (PG) with large surface area was prepared by equal volume impregnation. Catalytic reforming of biomass tar over Ni/PG was studied using toluene as the model compound in the presence of CO₂. X-ray diffraction, transmission electron microscopy and CO₂-temperature programmed desorption were used to characterized the catalyst samples. The influence of CO₂ amount, reaction temperature, and Ni loading on toluene conversion, hydrogen yield, and carbon deposit was investigated. The results showed that three desorption peaks of CO₂ appeared on both PG and the Ni/PG catalyst. The toluene conversion and H₂ yield increased with the increase in the amounts of CO₂ and Ni content as well as the reaction temperature. At 800 oC and CO₂/PhCH₃ molar ratio of 0.2–0.26, the toluene conversion was the highest; the H2 yield reached the highest at CO₂/PhCH₃ molar ratio of 0.2. Carbon deposition decreased with increasing the CO₂ amount and reaction temperature.

Key words: biomass tar, toluene, palygorskite, catalytic reforming, carbon dioxide