Mechanistic insights into methanol steam reforming over a ZnZr oxide catalyst with improved activity

Methanol steam reforming (MSR) holds great potential for mobile hydrogen production, but it still requires an active and stable catalyst. In this work, we report a high-performance ZnZr-0.5 composite oxide catalyst for this reaction, with a hydrogen production rate of 2.80 mol center dot gcat -1 center dot h-1 and CO2 selectivity of 99.6% at a methanol space velocity of 22,762 mL center dot gcat -1 center dot h-1. It also exhibits superior long-term durability in the TOS test for more than 100 h. Such good activity results from a synergistic effect of ZnO-ZrO2 dual sites. ZrO2 is capable of stabilizing and storing more CH3O* and HCOO* intermediates while ZnO is in charge of the dehydrogenation of these key intermediates. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and chemisorption results reveal that the MSR reaction experiences successively the hydrolysis of methyl formate and dehydrogenation of formate. More importantly, it is found that H2O significantly promotes the dehydrogenation of HCOO* intermediate by directly participating in this reaction from pulse chemisorption experiments. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

This study reports a high-performance ZnZr-0.5 composite oxide catalyst for methanol steam reforming, which shows excellent catalytic activity and long-term stability. The synergistic effect of ZnO-ZrO2 dual active sites is crucial for the catalyst's activity.