(186d) Effects of Zeolite Dopant Atom Concentration on Noble Metal Nanoparticle Sintering Observed with in Situ UV-Vis Spectroscopy

Elucidating the mechanisms of catalyst deactivation is an important step in improving industrial catalyst lifetime, which will in turn lead to substantial cost savings via reduced operational downtime and reduced purchasing frequency of precious-metal-impregnated catalysts. Deactivation can be caused via sintering of catalytically active surface-supported metal particles. For this reason, we have investigated the behavior of zeolite-supported gold nanoparticles (ZEO@AuNPs) at high temperatures to better understand the role that zeolite dopant atom concentration and dispersion play in processes that lead to AuNP sintering. AuNP plasmon resonance position and intensity are sensitive to AuNP size and proximity. In leveraging this resonance, in situ UV-vis spectroscopy (corroborated by ex situ TEM) was used to track time-dependent changes in ZEO@AuNP size and abundance. These experiments indicated the operation of competing sintering mechanism components, namely Ostwalt ripening and particle coalescence. Our findings are complimented by computational models of AuNPs on zeolite surfaces, which suggest correlation between the ease of mobility for ZEO@AuNPs and the energetic landscape of the zeolite’s surface. Data and analyses from experiments on these materials will be presented with context provided by computational models.