Study on the promotion of FeOx species on water-gas shift reaction in methanol aqueous phase reforming over PtFe/Al2O3 catalyst

Hydrogen production by catalytic aqueous phase reforming (APR) of biomass-derived oxygenates is a promising route to produce hydrogen in a renewable way. As the typical APR catalyst, Pt/Al2O3 is confronted with high methanation activity that consumes H2 and produces undesired CH4 during the treatment of methanol solution. In contrast, WGS reaction is the main pathway to boost H2 generation during APR process. In this work, a series of PtFe/Al2O3 catalyst with different Fe contents were prepared, characterized and tested for the methanol APR reaction. XRD, TEM, XPS and H2-TPR technologies were applied to study the change of physicochemical properties with the addition of iron. The restriction on methanation and promotion on WGS reaction were proved as well. With the increase of Fe content, the interaction between Pt and FeOx species have both positive and negative effects on APR reactivity while the CH4 selectivity descending continuously from 9.25% to as low as 0.60%. Besides, the effects of reduction temperatures (250–350 °C) of Pt0.5Fe/Al2O3 catalyst on APR performances were also investigated. An "Oxygen dynamic transfer cycle" between H2O/CO∗ and FeOx species with oxygen vacancies is proposed and verified. This indirect WGS reaction through lattice oxygen on FeOx species that boosting WGS reactivity helps improving H2 selectivity in the gas products of methanol APR.