Aqueous phase reforming of methanol for hydrogen production over highly-dispersed PtLa/CeO2 catalyst prepared by photochemical reduction method

Abstract

Hydrogen production by catalytic aqueous phase reforming (APR) of biomass oxygenated derivatives in relatively mild conditions is a promising way to produce hydrogen. In this work, Pt/CeO2-HT, Pt/La–CeO2-HT and PtLa/CeO2 catalysts were synthesized by a novel photochemical reduction method and applied to the methanol APR. Extensive characterizations have proved that the mild catalyst preparation method gave it a high dispersion of Pt species and the addition of La modified the metal-support interaction. The results showed that La-modified Pt/La–CeO2-HT and PtLa/CeO2 catalysts exhibited better catalytic performance than the Pt/CeO2-HT catalyst, among which the hydrogen yield was the highest for the surface La-modified PtLa/CeO2 catalyst (177.7 mmol/gcat). This was mainly attributed to the surface modification of La resulted in a significant increase in the number of moderately strong basic sites and surface oxygen vacancies in the PtLa/CeO2 catalyst. The enhancement of catalyst basicity effectively promoted the dissociation of H2O to produce hydroxyl groups, while a large number of surface oxygen vacancies provided more active sites for the adsorption and dissociation of H2O. And their synergistic behavior efficiently facilitated the water gas shift (WGS) reaction, resulting in a significant increase in hydrogen yield of methanol APR. Associated with the in situ DRIFTS analyzes and the results indicated by WGS reaction, possible promotion mechanism was proposed.