Non-precious Metal Catalysts for Acetic Acid Reduction
Acetic acid (AA) hydroconversion was studied over various monometallic (Fe, Co, Ni, Cu, Zn, Pt) and bimetallic (doped with In as second, guest metal) catalysts loaded on a highly mesoporous, fumed silica support. The transformations were investigated in a fixed bed, flow-through reactor in temperature range of 240-380°C using hydrogen flow at 21bar total pressure. The catalyst precursors were activated in H2 flow at 21bar and 450°C as routine pre-treatment. Catalytic performances of the studied metal catalysts have nothing in common. Activities and the yields of main products contrast strikingly. Diversity of catalytic behaviour reflects the complexity of the surface reaction network. Contrary to the highly ethanol selective Co or Cu forms, over Ni catalyst mainly methane was produced. Indium doping can completely eliminate the hydrodecarbonylation activity and turn to the consecutive reduction route resulting in high ethanol yield. Metallic phases of different peculiarities can offer promising contacts for upgrading various oxygenates obtainable from biomass degradation.