Metal/acid bifunctional catalysis and intimacy criterion for ethylcyclohexane hydroconversion: when proximity does not matter

Abstract : The apparent kinetics in metal/acid bifunctional catalysis is generally strongly affected by the metal to acid sites ratio, and their proximity. Although, these two key parameters are not systematically investigated in scientific literature. Such study is provided here for bifunctional catalysts using platinum as metallic function and EU-1 zeolite as acidic function. Two series of bifunctional catalysts with different metal to acid sites ratios and different metal to acid sites distances were prepared and tested in ethylcyclohexane hydroconversion. Increasing the metal to acid site ratio, the catalytic activity and isomerization selectivity increased until a plateau was reached, an observation which is in agreement with the classical bifunctional mechanism. At the same time, the intimacy criterion of Weisz was evaluated: strikingly, for a given metal to acid sites ratio, activities and selectivities are not affected by their distance (up to a micrometer scale). A dual function kinetic model was successfully applied in order to quantify