CO Oxidation on Au-Ag Alloy Nano-Catalysts and the Kinetic Study under H2-Rich Atmosphere

The first part in this thesis, we demonstrated surface functionalized mesoporous SBA-15 thin film as supporting host to confine the gold and silver alloy nanoparticles. We then show its PROX activity is surprisingly high. Proton exchange membrane fuel cells (PEMFC) have been extensively studied in the past decade. Pure hydrogen source is the ideal fuel for mobile energy systems. However, the Pt anode catalysts would be significantly poisoned by traces of CO in reformed gases. To fulfill the high purification requirement, the preferential oxidation of CO (PROX) appears as the most promising approach and the lowest cost technique. In general, the premise for good PROX performance is to choose a catalyst with more oxidation activity for CO than for H2. Recently we found that Au-Ag alloy catalyst showed a relatively high activity and selectivity.
In the second part of this thesis, Au-Ag alloy catalyst supported on MCM-41 was used for kinetic measurements of CO oxidation under H2-rich atmosphere. For this catalyst, it not only performs high CO conversion and CO2 selectivity, but also shows satisfactory stability. Many characterization techniques were used to study the catalyst system, such as nitrogen adsorption, TEM, XRD, EXAFS (X-ray absorption fine structure spectroscopy), and UV-Vis spectroscopy. Especially, EXAFS was employed to determine the coordination number and the degree of alloying formation.