Correlating low-temperature hydrogenation activity of Co/Pt(111) bimetallic surfaces to supported Co/Pt/γ-Al2O3 catalysts

The low-temperature self-hydrogenation (disproportionation) of cyclohexene was used as a probe reaction to correlate the reactivity of Co/Pt(111) bimetallic surfaces with supported Co/Pt/γ-Al2O3 catalysts. Temperature-programmed desorption (TPD) experiments show that cyclohexene undergoes self-hydrogenation on the ~1 ML Co/Pt(111) surface at ~219 K, which does not occur on either pure Pt(111) or a thick Co film on Pt(111). Supported catalysts with a 1:1 atomic ratio of Co:Pt were synthesized on a high surface area γ-Al2O3 to verify the bimetallic effect on the self-hydrogenation of cyclohexene. EXAFS experiments confirmed the presence of Co–Pt bonds in the catalyst. Using FTIR in a batch reactor configuration, the bimetallic catalyst showed a higher activity toward the self-hydrogenation of cyclohexene at room temperature than either Pt/γ-Al2O3 or Co/γ-Al2O3 catalysts. The comparison of Co/Pt(111) and Co/Pt/γ-Al2O3 provided an excellent example of correlating the self-hydrogenation activity of cyclohexene on bimetallic model surfaces and supported catalysts.