Migration of Zeolite-Encapsulated Pt and Au Under Reducing Atmospheres

Unbiased density functional global optimisation calculations, followed by kinetic Monte Carlo simulations are used to enumerate the potential energy surfaces for migration of noble metals Pt and Au inside the pore system of siliceous zeolite LTA. The effects of reducing adsorbates CO and H2 are determined. It is found that the two metals differ significantly in the strength and type of interaction with the framework, with strong, framework breaking interactions between Pt and and the zeolite, but only weak dispersive interactions between Au and the zeolite. Adsorbates are found to dramatically interfere with Pt-framework binding, leading to poorer atom-trapping, enhanced metal migration and faster equilibration.