Outstanding efficiency of indium in bimetallic catalysts for hydroconversion of bioacids to bioalcohols

• Indium doped catalysts are highly efficient for acetic acid reduction to ethanol.
• Modification with indium resulted in the change of the reaction mechanism.
• Turnover frequencies are not dependent on the Pt loading.

Step by step reduction of acetic acid (AA) to ethanol was investigated over novel bimetallic catalysts (PtIn/Al2O3) for the processing of VFAs (volatile fatty acids) that can be produced simply by thermochemical or biological biomass degradation. A fixed bed flow-through reactor was applied with hydrogen stream at 21 bar total pressure in the temperature range of 220–380 °C. AA hydroconversion activity of the parent alumina supported Pt catalyst and the yield of selectively produced alcohol can be increased drastically by In2O3 addition. Appearance of metallic indium creating a bimetallic catalyst can direct the consecutive catalytic reduction to ethanol formation inhibiting hydrodecarbonylation. Comparing the In-containing bimetallic catalysts studied recently, NiIn-catalyst showing similar activity to that of the PtIn-catalyst can be a cheap substitute for the expensive Pt catalysts in the reduction carboxylic acids.

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