Investigation on the hydrogen production by methanol aqueous phase reforming over Pt/CexMg1-xO2 catalyst: Synergistic effect of support basicity and oxygen vacancies

Abstract

Green hydrogen production from biomass oxygenated derivatives (methanol, ethanol, ethylene glycol, etc.) by low temperature aqueous phase reforming (APR) has the advantages of high hydrogen selectivity and low energy consumption. A series of CexMg1-xO2 mixed oxide supported catalysts were synthesized by a simple citric acid combustion method. The results show that these catalysts exhibit excellent water-gas shift reaction activity and CO is rarely detected in the products, which is due to their abundant oxygen vacancies of the mixed oxide supports of the Pt/CexMg1-xO2 catalysts. At the same time, the introduction of MgO provides more strong basic sites on the surface of mixed oxide support, and the methanol conversion and hydrogen yield show a volcano peak with the increasing number of basic sites and the hydrogen production reaches the highest (127.16 mmol) over Pt/Ce0·5Mg0·5O2 catalyst. The mixed oxide supported Pt/Ce0·5Mg0·5O2 catalyst enjoys the benefits of both oxygen vacancies in accelerating H2O adsorption/dissociation and strong basic sites in contributing to the formation of formate group (HCOO*), which improve the oxidation of CO* and APR activity. This synergistic effect is conducive to improve hydrogen yield of methanol APR and reduce CO selectivity to a minimum level.