Evaluation of Pd-based catalysts and the influence of operating conditions for autothermal reforming of dimethyl ether

A series of different Pd-based catalysts supported on ceramic monoliths were synthesized and tested in a screening study for autothermal reforming of dimethyl ether (DME). Alumina-supported Pd was shown to be very active for this reaction at temperatures between 350 and 400 °C. Adding Zn to Pd/γ-Al2O3 decreased the activity of decomposition reactions leading to better reforming activity, and resulting in high selectivity to carbon dioxide. Pd-Zn/γ-Al2O3 was further evaluated in a parameter study varying oxygen-to-DME ratio, steam-to-DME ratio and temperature. The effect on the reformer performance of changing the operating conditions is discussed. The Pd-Zn/γ-Al2O3 catalyst generated carbon monoxide concentrations below 5%, and hydrogen concentrations close to 50%. The catalyst performance was significantly improved by preconditioning in hydrogen. Results from a first round of catalyst characterization studies suggest that Pd–Zn species are formed on the alumina support following reduction.