Steam reforming of acetic acid over MgAl2O4-supported Co and Ni catalysts: Effect of the composition of Ni/Co and reactants on reaction pathways

Article abstract of DOI:10.1016/j.cattod.2017.04.023

The steam reforming of acetic acid (AcH), a model compound of pyrolysis-oil, was studied over MgAl₂O₄-supported Co-Ni catalysts with different Co/Ni ratios, prepared by impregnation using the incipient wetness method. The catalysts were characterized by X-ray powder diffraction, temperature programmed reduction, temperature programmed desorption, and thermogravimetry. In the steam reforming reaction of AcH, both Ni and Co catalysts suffered partial oxidation due to contact with the reaction mixture. The ketonization reaction occurred on the MgAl₂O₄ support and the presence of Co or Ni changed the reaction pathway of species adsorbed on the support, which suppressed the formation of acetone. The cleavage of C[sbnd]C bonds was favored on the Ni surface, resulting in CH_x species, which in the presence of H₂ were preferentially hydrogenated to CH₄ at low temperatures. On the other hand, on the Co surface the CH_x species were decomposed to C* and H* as the temperature increased. The addition of Co to Ni catalysts inhibited CH₄ formation and carbon accumulation.