Propylene oxide (PO) is one of the top chemicals produced worldwide by mass.  All of the commercial methods for (PO) production consume H2 as a reactant or produce significant amounts of co-products. This puts additional economic constraints on PO production. An efficient process for directly oxidizing propene to propylene oxide using molecular oxygen as oxidant could improve reaction efficiency and process economics. Density functional theory (DFT) calculations were performed to find suitable catalysts for direct propene epoxidation. Seven Zr/Hf-based catalysts with redox active ligands have been studied. Complete reaction cycles for each catalyst were computed, including ground state and transition state energies. Relative chemical potential diagrams have also been calculated to demonstrate the catalytic reaction trend under oxygen or propene rich conditions. Energy spans have been computed and possible side reactions have been tested for all seven catalysts. (The energy span is the difference between the most stable ground state and the highest transition state along the preferred reaction cycle.) Our best direct propylene epoxidation catalyst has an energy span of only 24.0 kcal/mol. To the best of our knowledge, this is lower than any of the previously reported direct propene epoxidation catalysts.

Computational studies of Zr/Hf based direct propene epoxidation catalysts

247th National Meeting (2014)

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