Single-Step Synthesis of Dimethyl Ether from Syngas over Nanoparticle-Derived Bifunctional Pd/CeO2/Al2O3 Catalysts.

The single-step syngas-to-dimethyl ether (STD) process offers both economic and technical advantages over the current two-step industrial process that utilizes Cu/ZnO/Al2O3 catalysts. Here, we report a highly active bifunctional Pd/CeO2/γ-Al2O3 catalyst, in which Pd colloids dispersed in a nanoscale CeO2 matrix serve as the key building block for the methanol-active component, efficiently catalysing the STD reaction. For Pd/CeO2/γ-Al2O3 with a high Pd-CeO2 interface concentration, CO conversion and dimethyl ether yield are significantly increased compared to Pd supported on Al2O3. Systematic investigations using spectroscopic and microscopic techniques reveal the formation of highly dispersed palladium clusters/particles confined within the nanoparticulate CeO2 matrix. The superior catalytic performance in both activity and stability observed for the Pd/CeO2/γ-Al2O3 in the STD reaction stems from the active cationic palladium interfacial species and the presence of adjacent O vacancies.