Syngas production from methane dry reforming over Ni/Al₂O₃ catalyst

Abstract

We evaluated dry reforming of methane in a tubular fixed-bed reactor at various reaction temperatures from 923 to 973 K using different reactant compositions over 10 % Ni/Al₂O₃ catalyst prepared by a wet impregnation method. Both NiO and NiAl₂O₄ phases were formed on the catalyst surface during calcination, and the 10 % Ni/Al₂O₃ catalyst possessed high surface area of 106.36 m² g⁻¹ with fine metal dispersion. The low activation energy observed for formation of NiAl₂O₄ phase during calcination indicated strong interaction between the NiO form and the γ-Al₂O₃ support. The NiO phase was completely reduced to metallic Ni⁰ form via H₂ reduction. The conversions of CO₂ and CH₄ increased noticeably with increasing CO₂ partial pressure, and the H₂/CO ratio was always below unity, regardless of reaction conditions. The yield of H₂ was enhanced with growing CO₂ partial pressure, approaching a highest value of about 70 %. The heterogeneous nature of the deposited carbon was evident from the coexistence of carbon nanofibers and graphitic carbon. In addition, the amount of filamentous carbon appeared to be slightly less than that of graphitic carbon. However, these deposited carbons were completely removed by O₂ at below 900 K during temperature-programmed oxidation.