Fuel Processing Technology, Vol.127, 26-32, 2014
Development of Ni-Fe bimetallic based catalysts for biomass tar cracking/reforming: Effects of catalyst support and co-fed reactants on tar conversion characteristics
Catalytic activities of Ni- and Ni-Fe bimetallic based catalysts supported by palygorskite, MgO-Al2O3, La0.8Ca0.2CrO3, and La0.8Ca0.2CrO3/MgO-Al2O3 toward the cracking and reforming of naphthalene and toluene (as biomass tar model compounds) as well as real biomass tar from pyrolysis of eucalyptus wood chips were studied. At 700-900 degrees C, the main products from the cracking of these hydrocarbons are H-2, CH4, C2H4, C2H6, and C3H6. Among all catalysts, Ni-Fe supported by MgO-Al2O3 and La0.8Ca0.2CrO3/MgO-Al2O3 show the highest H-2 yield values and good resistance toward carbon deposition. Additions of H2O and CO2 can promote steam and dry reforming, from which H-2 and CO were the major products from the reaction and the amount of carbon formation was considerably reduced. Importantly, the H2O/tar and CO2/tar ratios strongly affect the H-2 yield value, particularly for Ni-Fe/La0.8Ca0.2CrO3/MgO-Al2O3 due to the presence of perovskite-based La0.8Ca0.2CrO3. At proper H2O/tar and CO2/tar ratios, La0.8Ca0.2CrO3 behaves like the partly-reduced metal-oxide catalysts and promotes the reforming activity. Addition of O-2 along with H2O and/or CO2 can further reduce the carbon formation and increase the H-2 yield. Nevertheless, excess O-2 could oxidize metal particles and combusted H-2 to H2O, which causes lower H-2 yield production. (C) 2014 Elsevier B.V. All rights reserved.