An inverse ceria–copper catalyst for effective methanol steam reforming

Abstract

Methanol is a promising hydrogen carrier for fuel cell vehicles (FCVs) via the methanol steam reforming (MSR) reaction. Ceria-supported copper catalysts have garnered significant attention due to their remarkable oxygen storage capacity and abundant oxygen vacancies. Herein, we developed a colloidal solution combustion (CSC) method to synthesize an inverse catalyst. Compared with supported catalysts, the inverse Cu_0.9Ce_0.1O_x catalyst exhibits a larger copper surface area and abundant copper–ceria interfacial sites, contributing to an outstanding H₂ formation rate of 1.28 mol g_cat⁻¹ h⁻¹ at 250 °C. The linear correlation between turnover frequency values and interfacial O_V–Ce³⁺ length indicates the crucial role of the Cu⁺–O_V–Ce³⁺ sites. Kinetic studies reveal significantly lower apparent activation energy and reduced reaction orders of reactants on the inverse Cu_0.9Ce_0.1O_x catalyst. Furthermore, mechanistic studies demonstrate the diversity of rate-determining steps on inverse and supported catalysts. Both the dehydrogenation of CH₃O* and the reaction between formate species and hydroxy groups are kinetically facilitated on the supported Cu_0.1Ce_0.9O_x catalyst. This work introduces a solution combustion method to synthesize a highly active inverse copper–ceria catalyst, which can also be extended to other heterogeneous catalytic systems towards rational design of high-performance catalysts.