Metal-Support Interactions in the Pt/MgO System

Abstract Comparison of hydrogen chemisorption and transmission electron microscopy results for Pt/MgO catalysts has shown that the reduction temperature strongly influences the hydrogen adsorption capacity of the platinum. Hydrogen adsorption uptakes decrease significantly when the reduction temperature is increased from 300 to 500° C, but TEM results show only minor effects of reduction temperature on platinum crystallite size distributions. Hence, electronic interactions have to occur between Pt and MgO as a result of reduction at elevated temperatures. Treatment of Pt/MgO in oxygen at 550 and 650° C results in the formation of PtO x -MgO surface complexes. Decreases in platinum crystallite sizes can be achieved by reduction of catalysts after treatment in oxygen at 550° C.