CARBON MONOXIDE ADSORBTION AND CARBON MONOXIDE OXIDATION STUDIES ON THIOLATE SUPPORTED GOLD NANOCLUSTERS DISPENSED ON METALLIC OXIDES

Abstract

Thiolate-protected gold nanoclusters Aun(SR)m (n = 38, 40; m = 24) represent atomically well-defined active centers for catalysis with resolved crystal structures, enabling the creation of a homogeneous and defined surface. In this work, Aun(SR)m (n = 38, 40; m = 24) supported by Al2O3 and CeO2 are studied and characterized using techniques such as Thermogravimetric Analysis, Fourier Transform Infrared Spectroscopy and Kinetic Tests. The results from these measurements answered open questions related to the effects of pretreatment conditions, support material and the number of gold atoms. Thermogravimetric Analysis on bare gold nanoclusters showed that the thermal removal in oxidative and inert atmosphere is a three-step procedure for Au40(SR)24. For the Fourier-Transformed Infrared Spectroscopy and Kinetic Tests 473 K was taken as the pretreatment temperature. For the pretreatment atmosphere either oxidative, inert or reductive atmosphere was taken pretreatment, in order to investigate and validate observations from literature. The kinetic results are compared to gold nanoparticles Au/Al2O3 and Au/CeO2. The correlation of characterization via FT-IR spectroscopy with kinetics studies gives insight into the gold clusters’ activity and tests their utilization to bridge the gap between organometallic complex-based homogenous catalysis and nanoparticle based heterogeneous catalysis as well as the gap between the bulk crystal structure model catalysis and real-world catalysis.