Selection of modifying additives to enhance the stability of methane burning Pd-catalysts to water vapor

The article discusses the problem of methane post-combustion in the exhaust gases of automobile engines fueled by natural gas. In conventional converters PdO/Al2O3 catalyst is used, which main drawback is activity decreasing under the influence of water vapor that always present in exhaust gases. To increase the resistance to water vapor is prepared and investigated a series of binary catalysts PdO–MexOy/Al2O3 (Me – Co, Cu, Fe, Ni, Mn and Sn). Comparative tests under conditions simulating the process of methane post-combustion in the automotive converters have shown that Pd-catalysts promoted with oxides of nickel, cobalt and tin are more resistant to the inhibitory effect of water vapor. The stability of catalysts in the presence of water vapor caused by high PdO crystallinity and its uniform distribution over the surface of modified Al2O3. Optimization of quantity and route of promoters adding will almost completely eliminate the deactivation of Pd-catalysts under the influence of water vapor.

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