ZnFexAl2-xO4 spinel supported PdZnβ bifunctional catalyst for methanol steam reforming

Abstract

PdZnβ alloy catalysts, long regarded as a very promising copper replacement, not only possess copper-like reactivity, but also have superior thermal and chemical stability as well as non-pyrophoric nature that copper catalysts lack. In this contribution, we successfully synthesized the ZnFexAl2-xO4 (x = 0.05–0.2) spinel support, i.e., by replacing Al with a small amount of Fe in ZnAl2O4 spinel. The synthesized support, featuring a high surface area and superior stability, enabled the PdZnβ alloy formation at extremely low Pd loadings (e.g., 1000 ppm Pd), which shows high reactivity and CO2 selectivity toward methanol steam reforming (MSR) reaction. Moreover, it has the unique advantage of constructing bi-functional sites with a specific interfacial structure like PdZn/Fe2O3, the latter of which can effectively enhance water dissociation. Thanks to the synergetic effect, the 0.1 wt% Pd/ZnFe0.1Al1.9O4 catalyst exhibits a much higher ATOF value during the MSR reaction than the 0.1 wt% Pd/ZnAl2O4 counterpart, demonstrating excellent atomic utilization efficiency of noble metal and great potential in the practical application.