Inverse ceria-copper catalyst for effective methanol steam reforming

Abstract

Methanol is a promising hydrogen carrier for fuel cell vehicles (FCVs) via 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 the inverse catalyst. Compared with supported catalysts, the inverse Cu0.9Ce0.1Ox catalyst exhibits larger copper surface area and abundant copper-ceria interface, contributing to the outstanding H2 formation rate of 1.28 mol·gcat-1·h-1 under 250 oC. The linear correlation between turnover frequency values and interfacial OV-Ce3+ length indicates the crucial role of the Cu+-OV-Ce3+ sites. Kinetic studies reveal significantly lower apparent activation energy and reaction orders of reactants on inverse Cu0.9Ce0.1Ox catalyst. Furthermore, mechanistic studies demonstrate the diversity of rate-determining step on inverse and supported catalysts. Both dehydrogenation of CH3O* and reaction between fomate species and hydroxy groups are kinetically facilitated on supported Cu0.1Ce0.9Ox catalyst. This work introduces solution combustion method to synthesize highly active inverse copper-ceria catalyst, which can also be extended to other heterogeneous catalytic systems towards rational design of high-performance catalysts.