Synthesis and evaluation of highly dispersed SBA-15 supported Ni-Fe bimetallic catalysts for steam reforming of biomass derived tar reaction

Abstract

Highly dispersed Ni-Fe bimetallic catalysts supported on mesoporous SBA-15 were synthesized via an incipient wetness impregnation method by impregnation of a small amount of oleic acid mixed with a metal precursor on the SBA-15 support. This catalyst system was then tested for the steam reforming of biomass tar. Cellulose was used as a biomass model compound for this reaction. Among the various compositions tested, an optimum catalyst composition of 6Ni-1Fe/SBA-15 gave superior catalytic performance in terms of stability and activity. At 600 °C, about 90% of biomass was converted to gaseous products over the 6Ni-1Fe/SBA-15 catalyst, which was the highest among all the catalysts tested. From X-ray diffraction analysis, the Ni metal and Ni-Fe alloy crystallite sizes were barely distinguishable due to the formation of nano-catalysts less than 3 nm in size. Metal particles of less than 3 nm in size were further confirmed through TEM analysis. Moreover, temperature programmed reduction studies indicate a uniform distribution of bi-metallic Ni-Fe species which possess strong metal-support interactions with the mesoporous SBA-15 support. This was also indicated via X-ray photoelectron spectroscopy results. TGA studies over the spent catalysts showed that all Fe containing catalysts generally had lower carbon deposition rates compared to those over the 7Ni/SBA-15 catalyst.