Unravelling the morphology effect of Pt/In2O3 catalysts for highly efficient hydrogen production by methanol steam reforming

Abstract

Methanol steam reforming (MSR) constitutes an attractive reaction for high-yield on-board hydrogen production for H2-fueled fuel cell applications. Engineering the morphology of Pt/In2O3 heterogeneous catalyst is a feasible strategy for efficient MSR catalyst design, which can construct the Pt2+-In2O3 interfacial sites by utilizing the interaction between Pt and In2O3, thereby facilitating oxygen vacancy creation and activating methanol and water molecules. In this work, three kinds of In2O3 supports with different morphologies of nanorods, nanocubes and nanoplates were synthesized, and Pt/In2O3 catalysts were prepared by deposition–precipitation method. The performance of the catalysts for MSR hydrogen production was evaluated at 250 ∼ 375 ℃. The rod-shaped Pt/In2O3 catalyst with extremely low loading of Pt (0.21 wt%) exhibited the superior catalytic activity compared to the other two counterpart catalysts, achieving the complete CH3OH conversion and the CO selectivity as low as 3.8 % at 325 ℃. Moreover, the performance of Pt/r-In2O3 catalyst remained stable during the stability test for up to 40 h. Based on XRD, BET, HRTEM, XPS, Raman, UV–vis and H2-TPR characterization methods, the observed morphology-dependent reactivity of Pt/In2O3 catalysts can be correlated to the good low-temperature reducibility, abundant surface Pt2+ and adsorbed reactive oxygen species, which was originated from the exposed (211) crystal planes. The preferential exposed (211) crystal plane enables a stronger interaction of In2O3 support with Pt species resulting in the synergistic effect of high oxygen vacancy content, high proportion of Pt2+, and the formation of Pt2+-In2O3 interface active sites, which facilitates the activation and conversion of methanol and water molecules. The developed strategy may provide insight into the development of the design principles for high-performance methanol reforming catalysts for hydrogen production.