Highly selective bimetallic Pt-Cu/Mg(Al)O catalysts for the aqueous-phase reforming of glycerol

Abstract

Monometallic Pt and bimetallic Pt-Cu catalysts supported on Mg(Al)O mixed oxides, obtained by calcination of the corresponding layered double hydroxides (LDHs), were prepared and tested in the aqueous-phase reforming (APR) of glycerol. The effect of the Mg/Al ratio and calcination temperature of the LDH support, as well as the effect of varying Pt and Cu amounts on glycerol reforming, was investigated. The use of a basic support increases the selectivity to hydrogen and the use of a Pt-Cu bimetallic catalyst results in a decrease in alkane formation. The 0.9 wt.% Pt-0.4 wt.% Cu/Mg(Al)O_2.95 catalyst system with an Mg(Al)O mixed oxide support obtained by the calcination of the corresponding LDH material with Mg/Al ratio of 2.95 at 673 K, showed higher hydrogen selectivity (55.3%) and lower methane production (1.9%) after 5 h reaction than the benchmark Pt/Al2O3 catalyst (49.4% and 5.6%, respectively). Catalyst characterization by extended X-ray absorption fine structure (EXAFS) spectroscopy showed a bimetallic interaction between Pt and Cu. The bimetallic interaction is thought to be responsible for the lowered methane formation and, ultimately, the high hydrogen selectivity observed.