Investigation of Active Site Environment of Zeolite-Supported and Encapulated Palladium Nanoparticles for Methane Partial Oxidation to Methanol by Hydrogen Peroxide

Abstract

Methanol is an important platform chemical in the chemical, fuel, and polymer industries, which, conventionally, requires energy intensive conditions to produce. Methane partial oxidation to methanol by hydrogen peroxide offers a sustainable alternative which, depending on catalyst design, may occur at milder conditions and enable methanol production from methane at remote locations. This study investigated palladium nanoparticles supported on and encapsulation in MFI as catalysts for hydrogen peroxide decomposition and methane partial oxidation to methanol. Pd-proximal H+ sites were found to decrease rates of hydrogen peroxide decomposition by a factor of 23 for nanoparticles supported in H-MFI compared to amorphous silica. Pd sites were found to be inactive towards MPO by hydrogen peroxide to liquid products at the conditions studied but Pd-free MFI catalysts showed appreciable liquid product formation, with yields and selectivities varying based on cations present in the support. These results demonstrated the promise of bifunctional H- and Na-MFI supported or encapsulated palladium nanoparticles for hydrogen peroxide synthesis and methane partial oxidation to methanol by hydrogen peroxide.