Novel CeO₂-based Oxides Washcoats Onto Cordierite Honeycomb And Their Utilization As Pd Supports For VOCs Combustion

Volatile organic compounds (VOCs) are well-known as one of the major contributors to air pollution. Among current technologies for controlling VOCs, catalytic combustion technology has been regarding as the most effective ones due to its simple equipment and eliminating VOCs at relatively low temperatures. And the catalyst is the key of catalytic combustion. This study is tried to investigate new washcoats supported Pd on cordierite honeycomb, based on high properties of VOCs catalytic combustion of supported-Pd catalysts. The washcoats and their supported-Pd catalysts were characterized by XRD, Raman spectroscopy, H2-TPR, and SEM techniques.It finds that Y2O3 novel washcoat prepared by an impregnation method can anchor and interlocks well on the substrate. Moreover, the Y2O3 washcoat suits as a support to prepare a Pd catalyst onto the cordierite honeycomb substrate. There exists CO₃^2- species on the surface of the Pd/Y₂O₃ catalysts calcined at lower temperatures, while with increasing the calcination temperature CO₃^2- species disappear. During H₂-TPR, CO₃^2- species desorbed at low temperature easy reacted with H₂ resulting in CH4. Owing to highly dispersed PdO species and its strong interreaction with the Y₂O₃ washcoat, the Pd/Y₂O₃ catalysts hold highly catalytic properties and thermal stability. But sinter and decomposition of PdO are the main reasons for decline of the catalytic activities.Novel Ce_xY_1-xO_δ washcoats on cordierite honeycomb can anchor well Pd onto the cordierite honeycomb substrate, which are fit for preparation of Pd-based catalysts (x<0.8). The results show that compared to conventional washcoats the Ce_xY_1-xO_δ washcoats have better adhesion and higher vibration-resistance. It shows that CeO₂ and Y₂O₃ are present as mixed oxides and the active species as PdO on the Pd/Ce_xY_1-xO_δ catalysts. The catalytic activities of Pd/Ce_xY_1-xO_δ catalysts have closed related to the washcoats, of which that of Pd/Ce_0.8Y_0.2Oδ catalyst are the best. The catalytic activities of Pd/Ce_xY_1-xO-δ catalysts is corresponding to the CO₂ desorption in...