USE OF CATALYTIC REACTIONS TO PROBE MG-AL MIXED-OXIDE SURFACES

In this work, we investigated the effect of catalyst composition on the surface reactivity of magnesium-aluminum mixed oxides using three probe reactions: dehydrogenation of 2-propanol to propanone, dehydration of 2-propanol to propene, and isomerization of 1-butene. Turnover rates were calculated from the total CO2 adsorption capacity of the mixed oxides, assuming one adsorption site corresponds to one active site. Turnover rates for the dehydrogenation of 2-propanol were independent of the catalyst composition, which is consistent with the structure insensitivity of dehydrogenation reactions. The other two probe reactions followed opposite trends with the Mg: Al ratio: as the Al content of the mixed oxides increased, the turnover rate for 2-propanol dehydration increased while that for 1-butene isomerization decreased. The magnitude of these changes confirms that the mixed oxides are truly interdispersed and not present as separate phases.