(675b) Role of Synthetic Additives in Catalysis: Ethylene Hydrogenation and Carbon Monoxide Oxidation Over Monodisperse Platinum Nanoparticles with Organic Capping Layers

Heterogeneous catalysis is a popular application for colloid synthesized metal nanoparticles because morphology control leads to well-defined structures, which may yield active site uniformity for high activity and selectivity. In this work, the role of synthetic additives on the catalytic properties is evaluated. Pt nanoparticles of 1.5 nm in size were synthesized by the same procedure (ethylene glycol reduction under basic conditions) with the various capping agents (oleylamine (OA), trimethyl tetradecyl ammonium bromide (TTAB), and polyvinlypyrrolidone (PVP)) added afterwards for stabilization. Before examining catalytic properties for ethylene hydrogenation and CO oxidation, the Pt NPs were deposited onto mesoporous silica (SBA-15) supports and characterized by transmission electron microscopy (TEM), chemisorption, and elemental analysis. For both reactions, PVP and TTAB capped Pt yielded similar turnover frequencies. However, OA capping exhibited a detrimental influence on the catalytic properties as deactivation and low activity were observed for ethylene hydrogenation and CO oxidation, respectively. This result was consistent with amine groups being poisons for Pt and highlights the effects of synthetic additives on the catalytic properties.