Combustion of Methane over Palladium Based Catalysts - A Study of Catalytic Deactivation The Use of Electrochemical Oxygen Pumping

摘要

Methane oxidation over palladium is of interest due to its clean catalytic combustion properties, forming only carbon dioxide and water. A successful palladium based catalyst will virtually eliminate polluting byproducts including unburned hydrocarbons, carbon monoxide, soot, and NOx. These potential benefits have have not been realized, in part due to catalyst deactivation over time. In this study we identify a relationship between catalyst deactivation and hydroxyl formation on Pd/Al_2O_3 and Pd/TiO_2 catalyst surfaces, using time series FTIR spectroscopy. FTIR analysis suggests that catalyst deactivation is caused by growth of surface hydroxyls at temperatures below 450℃, and that that oxygen mobility on the catalyst surface may correlate with the degree of catalytic deactivation.We also examine the use of electrochemical oxygen pumping through a yttrium stabilized zirconia (YSZ) membrane as a possible method of delivering oxygen to the methane catalytic combustion reaction and improving catalytic conversion. We observe that applying a potential across a YSZ membrane can result in moderate increases in methane conversion, and that oxygen concentration in reactant gas mixture has a dramatic effect on catalytic activity. Our study will also address electrochemical oxygen transport to determine its rate limiting impact on the methane catalytic combustion reaction.