Acetic acid hydroconversion to ethanol over supported nickel and indium-modified nickel catalysts

摘要

Volatile carboxylic acids (mainly acetic acid) can be produced efficiently by simple thermochemical or biological degradation of various biomasses. For the processing of such oxygenates in hydrogen atmosphere, acetic acid (AA) hydroconversion was studied in detail over zeolite-based Ni and bimetallic InNi catalysts in a flow-through reactor at 21 bar total pressure and 240-380 A degrees C. Efficient hydrogenating contacts were already obtained by in situ reduction of Ni-zeolites (A, X, P) and mainly co-reduction of their mixtures with In2O3 in H-2 flow at 21 bar and 450 A degrees C. Under these conditions, the bulk of charge-compensating nickel cations remained unreduced and therefore a large portion of the microporous zeolite structure was still preserved. Modification of the formed Ni particles with indium quest metal generated bimetallic NiIn/Ni,H-zeolite catalysts having higher hydroconversion activity with much lowered hydrodecarbonylation and with enhanced ethanol selectivity than the parent partially destructed Ni/Ni,H-zeolite. The activity dependence on the reactant partial pressure denotes rate-controlling surface reaction according to the Langmuir-Hinshelwood mechanism.