SGER: Thermal Effects in Microwave Enhanced Catalysts

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AbstractCTS-9907322J. Thomas/VPIThis research project is directed toward providing answers to fundamental questions concerning heat production and transport when microwave energy is used to promote chemical reactions on supported metal catalysts. These materials consist of nanometer-sized metallic particles distributed within a porous ceramic substrate. Microwave fields do not couple to the ceramic support at temperatures of interests in chemical reactions, but they may couple strongly to the metallic particles because of electron quantum confinement. This phenomenon offers the opportunity to selectively heat the catalyst particles to temperatures higher than the matrix. Selective heating can result in greater control over chemical reactions and possibly high selectivity for desirable products. Increased selectivity in microwave-enhanced chemical catalysis has been reported, but the causes are unclear. Because of the difficulty of measuring temperatures of nanometer-sized particles, no direct verification of selective heating has yet been achieved. This project will employ theoretical modeling and a novel experimental technique based on neutron absorption to determine whether catalyst particles are susceptible to selective heating by microwaves. Temperature measurement of nanometer-sized particles cannot be done by conventional techniques. Neutron resonance radiography will be used to resolve the temperatures of catalyst particle and support. The success of this method could open a new avenue for developing catalytic reactions.