Author ORCID Identifier

https://orcid.org/0000-0003-4853-1188

Defense Date

2020

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Chemistry

First Advisor

Scott Gronert

Second Advisor

Vladimir Sidorov

Third Advisor

Katharine Tibbetts

Fourth Advisor

Brian Fuglestad

Fifth Advisor

Kenneth Wynne

Abstract

Recent developments in heterogeneous catalysis has led to the conception of single-atom catalysts (SACs), a class of catalysts based on isolated metal atoms anchored to a support scaffold. SACs are often much more reactive and can offer better selectivity when compared to nano-scale catalysts. In order to realize the full potential of SACs, a sound understanding of the underlying catalytic mechanisms is required. However, surface analysis tools can become less effective in studying catalytic mechanisms at the atomic scale. Mass spectrometry has proven to be a robust technique for studying organometallic catalytic mechanisms at the single-molecule level. Using mass spectrometry, we have generated zero-valent metal complexes using Ni, Co, Cu, and Pd active centers. These ions can act as experimental model ions for pristine graphene-supported SACs.

When using Ni as the active center, the model ion is capable of the dehydrogenation of alkanes via two sequential C-H activations. By introducing energy into the system, additional dehydrogenations occur, enabling processes such as the transformation of cyclohexane to benzene. Both the Ni and Co SAC model ions are capable of the selective dehydrogenation of amines and alcohols via a similar dehydrogenation pathway. The Ni, Co, and Pd model ions are capable of engaging in oxidative addition with a variety of polar reagents. The Cu model ion seems to react with polar reagents via one-electron transfer processes. Our work suggests graphene-supported SACs are capable of engaging in dehydrogenation and oxidative addition. Kinetic isotope effects and DFT calculations support the proposed mechanisms.

Rights

© Michael Borrome

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

12-4-2020

 
 
 
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