Development of activity–descriptor relationships for supported metal ion hydrogenation catalysts on silica

Single-site heterogeneous catalysts receive increasing attention due to their unique catalytic properties and well-defined active sites. We report a combined computational and experimental study on a series of silica-supported metal ion hydrogenation catalysts (i.e., In³⁺, Ga³⁺, Zn²⁺, Mn²⁺, and Ti⁴⁺/SiO₂). These catalysts were synthesized, characterized, and evaluated for gas-phase propylene hydrogenation. Computational studies were carried out on active-site structures and reaction mechanisms. An activity–descriptor relationship was established, which correlates a computational quantity (reaction free energy of the metal hydride formation) with the experimental reaction rate, as a function of the metal. Microkinetic modeling provided qualitative kinetic insights into the activity–descriptor relationship. This relationship was used to predict the trend of activities in a variety of M/SiO₂ catalysts. These fundamental studies and the developed activity–descriptor relationship open up new opportunities for rational design of hydrogenation catalysts.