Steam reforming of acetic acid over MgAl 2O 4-supported Co and Ni catalysts: Effect of the composition of Ni/Co and reactants on reaction pathways

摘要

Graphical abstractDisplay OmittedHighlights?Oxi-reduction of the Co-Ni surface depends on reactants composition.?At low temperatures, fragments of acetic acid are hydrogenated to CH4over Ni.?The presence of Co in Co-Ni suppresses CH4formation at low temperatures.?CO and CO2formation occur via two different routes.?The presence of metal on catalysts changes the reaction pathway over the support.AbstractThe 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 MgAl2O4support 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 CC bonds was favored on the Ni surface, resulting in CHxspecies, which in the presence of H2were preferentially hydrogenated to CH4at low temperatures. On the other hand, on the Co surface the CHxspecies were decomposed to C* and H* as the temperature increased. The addition of Co to Ni catalysts inhibited CH4formation and carbon accumulation.]]>