ИСТИНА

In this work we studied the modification of the surface structure of supported Pd-Ag alloyed catalysts occurring upon adsorption of CO and O2 molecules by CO-FTIR. The obtained results showed that the main part of the active sites before CO or O2 adsorption were Pd1 centers isolated by Ag atoms. However, after the catalyst treatment in CO or O2, a significant increase in the number of Pd2 adsorption sites is observed in the IR spectrum. Such transformation had a significant impact on the catalytic properties of Pd–Ag catalysts, which were evaluated in the model reaction of selective liquid phase hydrogenation of diphenylacetylene. After CO or O2 adsorption we observed a significant increase in activity compared to the initial sample. It was also found that after treatment in CO, the selectivity of the catalyst in the formation of the target olefin (stilbene) remained almost unchanged. Adsorption of O2 led to more pronounced surface modification and a slight decrease in selectivity was observed. Presumably this is a result of the formation of Pdn (n > 2) polyatomic adsorption.