Highly selective production of syngas (>99%) in the partial oxidation of methane at 480 °C over Pd/CeO2 catalyst promoted by HCl

Abstract

The partial oxidation of methane (POM) is an attractive catalytic route for producing syngas (CO/H2), although there are problems to overcome such as high reaction temperature (>650 °C) and the deactivation of the catalyst due to the coke formation. We addressed the problem by including HCl in the POM over a Pd/CeO2 catalyst. Pd/CeO2 produces CO, CO2, and coke with low CO selectivity in the absence of HCl, while it converts methane to chlorinated products at below 450 °C in the presence of HCl. At above 480 °C, however, highly selective CO (>99%) is produced over Pd/CeO2 via the POM. Moreover, it is found that coke is not formed during the reaction, leading to the stable partial oxidation activity and selectivity up to 40 h. Both surface and bulk characterization results strongly propose that HCl plays an essential role in transforming Pd/CeO2 into (PdClx + Pd0)/CeOCl (0 < x ≤ 2), which provides the ideal environment for the catalytic route of the POM.