Cu and Cu2In nanoparticles supported on amorphized zeolites for the selective reduction of biomass derived carboxylic acids to alcohols

Octanoic acid (OA) was used as reactant with medium chain length to model the aliphatic carboxylic acids which can be produced by catalytic, thermochemical or biological degradation of biomass. A flow through reactor was applied at 21 bar total pressure (in general at 20 bar hydrogen and 1 bar octanoic acid partial pressures) and 330–380 °C. Cu A-, X- and Y-zeolite based catalysts were pretreated in hydrogen flow at 450 °C. During reduction/dehydration A- and X-zeolite structures collapsed and aluminosilicate supported copper catalysts were formed, which contain copper nanoparticles in high dispersion. The catalyst samples were modified by In2O3 co-catalyst. Fatty acid conversion activity of amorphized zeolite supported Cu catalysts and the yield of selectively produced alcohol can be increased drastically by In2O3 addition. Appearance of metallic indium can effectively rein in the step by step catalytic reduction at alkanol formation previous to dehydration of alcohols to alkenes and ethers.

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► In2O3 doping opens a novel route for catalyst development for fatty acid reduction.
► Destructed Cu-zeolites are effective in conversion of carboxylic acid to alcohol.
► Alcohol selectivity depends on the original zeolite structure.
► Carboxylic acid hydroconversion to alcohol can be increased by In2O3 doping.
► Cu2In alloy phase can direct the step by step catalytic reduction.