Date of Completion

8-1-2020

Embargo Period

8-1-2023

Keywords

Mesoporous, Nanomaterials, Heterogeneous Catalysis, Green, Sustainable, Renewable Energy

Major Advisor

Steven L. Suib

Associate Advisor

Alfredo Angeles-Boza

Associate Advisor

Gaël Ung

Associate Advisor

Jose Gascon

Associate Advisor

Fatma Selampinar

Field of Study

Chemistry

Degree

Doctor of Philosophy

Open Access

Open Access

Abstract

Research on novel highly active mesoporous metal oxides by an inverse micelle method dubbed University of Connecticut (UCT) materials for versatile catalytic reactions is reported. The first section discusses the synthesis of highly active mesoporous cobalt oxide for the elimination of 2-propanol. The superior activity is correlated to better low temperature reducibility, large pore volumes, higher Co3+/Co2+ ratios, and higher number of surface-active oxygen species. Reaction forms carbonyl and carbonate species on the surface of the catalysts before complete oxidation. The second section is devoted to the synthesis of high surface area cerium oxide and zirconium oxide catalysts for self-condensation of cyclopentanone which is an attractive building block for biomass upgrading processes. Strong basic sites of zirconium oxide are responsible for higher catalytic activity compared to cerium oxide. However, strong basic sites are responsible for deactivation of zirconium oxide whereas cerium oxide with lower basic site strength exhibited higher stability. The reaction mechanism involves a unimolecular α-H abstraction step, which forms an enolate. Then coupling of enolates with another cyclopentanone molecule occurs according to a detailed kinetic study. The last section is on the synergistic catalysis by manganese promoted cerium oxides for molecular oxygen assisted epoxidation. Materials exhibit superior activity for epoxidation of alkenes. The generation of superoxide anion and singlet oxygen on the surface of materials correlates with high catalytic activity. Multiple properties of catalysts such as fluorite crystal structure which facilitates high oxygen mobility, oxygen vacancies, lower valent states of manganese and cerium are crucial for catalytic activity.

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