Surface Science Analysis of Catalytic Thin Films: Pd-Based H₂ Separation Membranes and Pyridine-Assisted Cycloaddition of CO₂

Surface science experiments and techniques have assisted in invaluable ways to improve our understanding of heterogenous catalysis. Many applications investigate catalytic materials far from reaction conditions with model systems. Within this dissertation, I discuss the application of surface experiments and techniques at or near experimental conditions to further the understanding of two important catalytic systems: (1) Pd-based dense H₂ separation membranes and (2) Pyridine organocatalysis of the cycloaddition of CO₂ into an epoxide. For the thin metallic membranes I investigate common catalytic poisons, C₃H₆ and CO, on the activity of Pd during H₂ separation at relevant permeation conditions. I identify the existence of key surface and bulk species deposited on the membranes, outlining poisoning reaction conditions and providing baseline performance and surface poison comparisons of Pd to the most common alloy membrane Pd₇₇Ag₂₃. For the pyridine catalysis of CO₂, I utilize in situ spectroscopic analysis to improve understanding of the mechanism of CO₂ cycloaddition into epichlorohydrin. I show that pyridine isomers behave differently during reaction and identify the in situ quaternization reaction of poly-4-vinylpyridine. The experimental design and tools used in this dissertation can be improved and applied to further catalytic applications, some of which I discuss in the concluding remarks.