Silver Base Metal Zeolite Catalyst Development Research, And Aes

In this paper the deactivation mechanism of electrolytic silver catalyst has been studied. It was demonstrated that the primary reason for deactivation is carbon deposition on the catalyst surface. A new kind of Dual-metal Zeolite Catalyst Ag-cd-Y was prepared and the catalysis role of the new catalyst in the oxidization and dehydrogenation reactions of methanol into formaldehyde has been evaluated. Under same conditions, formaldehyde yield by using the new one was as same as that by using electrolytic silver catalyst, moreover its ability to constraints on carbon formation was stronger than that of electrolytic silver. The research employed AES and SEM shew Cadmium can reduce electronic state density and be useful to Ag dispersion in Y-zeolite. Because of Ag-cd cluster formation, the conditions of severe oxidation of methanol to CO₂ were destroyed, the reaction selectivity became well and the catalyst ability to constraints on carbon deposition increased .cadmium segregation from bulk to the surface in both catalyst preparation process and using process has been studied With AES combined with XPS Analysing. The former is due to cadmium atomization heat lower than silver; the latter is due to the action of adsorbed oxygen, In a certain range , cadmium segregation is favourable to the increase of the catalyst activity and selectivity.