Palladium-exchanged small-pore zeolites with different cage systems as methane combustion catalysts

The catalytic properties of four palladium-exchanged small-pore zeolites with different cage systems (i.e., Pd-SSZ-13, Pd-LTA, Pd-PST-7, and Pd-RTH) have been evaluated for methane (CH4) combustion and compared with those obtained from Pd-ZSM-5 and Pd-Al2O3 in an attempt to investigate the effects of zeolite support structure and acidity on the oxidation activity of supported Pd catalysts for this greenhouse gas. When Pd loading level was fixed to be ca. 1.0 wt%, Pd-SSZ-13 was found to show the best CH4 oxidation activity and durability under wet feed conditions among the catalysts studied. The overall characterization results of this work demonstrate that the strong acid strength of SSZ-13 may render strong interactions between the intrazeolitic PdO species and the zeolite framework so as to effectively suppress not only PdO sintering but also dealumination during CH4 combustion. (C) 2017 Elsevier B.V. All rights reserved.