Gurnyk T. Effect of the surface fractal dimension of silica and zirconia on their catalytic properties in reactions of carbon monoxide oxidation and synthesis of ethyl-tert-butyl ether

A quantitative approach to explain the effect of surface fractal dimension of catalyst on activation energy and pre-exponential factor of heterogeneous catalytic reaction was presented for the first time. Our theoretical results are in a good agreement with experimental studies of the CO oxidation on various porous silica and zirconia nanopowders. Our results indicate that the activation energy and the pre-exponential factor of rate constant of CO oxidation increases with increasing the surface fractal dimension of silica. For CO oxidation on zirconia with invariable value of the surface fractal dimension the activation energy does not change. If the activation energy is constant, the pre-exponential factor of rate constant of CO oxidation decreases with increasing the mass fractal dimension. For heterogeneous-catalytic reactions of acid-base type, on example of synthesis of ethyl-tert-butyl ether on the silica modified by zirconia and alumina, it was shown that antibate dependence of rate and "turnover frequency" on acidity of catalysts surface is related with change of the surface fractal dimension.