Rational engineering of nanostructured heterogeneous catalysts to achieve high robustness through modulating their metal-support interactions

Abstract

Engineering heterogeneous catalysts at a nanometer scale can significantly increase reactivity by the lowering activation energy and creating new transition states. Specifically, robust catalysts can be achieved by functionalizing small nanoparticles (i.e., active metals) onto nanostructured metal oxide (i.e., supports), which increases the surface areas of exposed active sites. However, traditional methods based on impregnation and nanoparticle deposition, and strong metal-support interaction suffer from nonuniform particle size distribution, lower dispersion of active sites, vulnerability to poisoning and sintering, and reversible transformation of oxide shells. Therefore, another approach that can overcome the critical issues is required in the field of heterogeneous catalysis. In this dissertation, I have studied synthesis strategies to design robust and durable catalytic materials for conversion reactions of carbon dioxide and volatile organic compounds. The strategies include: 1) rapid Joule heating synthesis using metal oxide-coated carbon nanofibers to embed a small portion of metal nanoparticles 2) The ex-solution process using metal-organic frameworks as oxide precursors to achieve effective doping and ex-solution at lower temperatures. 3) designed synthesis of ex-solution catalyst as high-performance oxygen carrier for reverse water-gas shift reaction operated in a chemical looping scheme The design principles and reaction mechanisms studied in this dissertation can serve as the key platform and provide mechanistic understandings to develop highly active and stable catalysts for various chemical reforming reactions.