Insights into direct/synergetic processes for high-efficiency steam reforming of methanol over Pt-In2O3/CeO2 catalysts: The effect of support structural properties

Abstract

The addition of Pt (1 %) and In2O3 (7 %) phases into CeO2 supports exhibited an interaction, resulting in the formation of bifunctional Pt2+-In2O3-CeO2, Ptδ+-CeO2 (0 < δ < 2), In2O3-CeO2, and inactive In2O3 macroparticles., Low CO selectivity was achieved in methanol steam reforming (MSR) by sacrificing methanol conversion/catalytic stability. Two distinct reaction paths were identified, viz., the direct process over bifunctional Pt2+-In2O3-CeO2 and the synergetic process between Ptδ+-CeO2 and In2O3-CeO2. The relative ratio of these two processes played a decisive role in determining the product distribution. The direct process improved methanol conversion while maintaining low CO selectivity. However, a decrease in catalytic stability was attributed to the agglomeration and sintering of the In2O3 phase, leading to the conversion of Pt2+-In2O3-CeO2 into Ptδ+-CeO2. To address the challenge of balancing methanol conversion/catalytic stability and CO selectivity, it was crucial to enhance Pt2+-In2O3-CeO2 sites and preserve their stability. Furthermore, the structural properties of the support played a significant role in governing the distributions and states of Pt and In2O3 phases. Specifically, the use of CeO2 (0.5 °C min−1) support resulted in a substantial increase in Pt2+-In2O3-CeO2 and effectively mitigated the sintering of In2O3 phases, ensuring the stability of Pt2+-In2O3-CeO2. In conclusion, our work elucidated the intricate relationships among the structural properties of CeO2 supports, the distributions and states of Pt and In2O3 phases, and MSR performance over Pt-In2O3/CeO2 catalysts, which hold promise for advancing the development of high-performance MSR catalysts.