The major sources of energies and materials that we use in daily life are produced by chemical reactions that break and form chemical bonds. These reactions can be controlled in specificity using catalysis, which enhances the rate of the desired reaction through the stabilization of the transition state that mediates such route. The demand for catalysis has recently grown even more with challenges in supplying fossil fuels and with growing concerns in global warming and environmental issues.

The main goal of my research group is to understand the identity and kinetic relevance of the requisite elementary steps involved in heterogeneous catalysis in order to ultimately design catalytic systems with improved reactivity and selectivity toward desired products. Such goal is achieved by rigorously combining atomic-level synthetic methods, characterization tools, and theoretical assessments, which allow us to understand and control catalytic reactions at a molecular-level. The results of our projects will provide mechanistic insights into current catalytic systems and help to develop new catalysts with minimal energy requirements and environmental impacts.

Selective oxidation of light alkanes with H2O2

Project Lead: Manasi Yvas

The abundance and low cost of natural gas has fueled a rising interest in establishing a process that selectively oxidizes alkanes to industrially important products. Hydrogen peroxide (H2O2), a green oxidant, can potentially facilitate the oxidation process by interacting with metal catalysts and generating electrophilic oxygen species. Recently, bifunctional catalysts have emerged as promising materials for overcoming C-H bond activation barriers in alkanes and in-situ H2O2 generation. My project aims to mechanistically explore light alkane oxidation with H2O2 on metal and metal oxide surfaces and nanoparticles. Through the use of theoretical assessments, characterization tools, and kinetic analyses, I hope to elucidate the nature of catalyst active sites, the impact of particle size and oxygen surface coverage effects, and the role of electrophilic oxygen species in alkane C-H bond activation.

Ethanol upgrade using engineered TiO2 catalysts with microporous SiO2 sieving layers

Project Lead: Yingxue Bian

Microporous SiO2 sieving layers can be deposited on anatase TiO2 material using atomic layer deposition (ALD) method, which allows the modification of SiO2 sieving layers structure including the size, shape and depth. The microporous SiO2 sieving layers on TiO2 catalysts is potential for increasing the selectivity of ethanol dimerization, with the confinement-induced control of molecular diffusion and transition state destabilization. Therefore, the reactivity and selectivity of ethanol to n-butanol will be studied on the SiO2 microporous layers covered TiO2 catalysts, and it can also provide mechanistic insights on confinement effects and optimization of microporous structures for higher reactivity and selectivity.

CO2 hydrogenation to liquid fuels

Project Lead: Michelle Nolen

Carbon dioxide valorization is an appealing extension of carbon dioxide capture. A variety of metal-based catalysts could facilitate the conversion of carbon dioxide into useful chemicals and liquid fuels, via hydrogenation and C-C coupling. However, there is a need for the thorough and innovative exploration of low-cost and efficient catalysts in this reaction. This project will use quantum mechanical simulations to design a catalyst for the conversion of CO2 to a useful product. The computational results will support experimental studies, completing a comprehensive investigation into key catalyst properties, reaction mechanisms, and active sites.

Mechanistic assessments of benzene alkylation on solid acids

Project Lead: Hanna Monroe

Benzene alkylation is an important process in the petrochemical industry to produce cumene and ethylbenzene. Zeolite catalysts are being utilized industrially due to their environmental and economic benefits over liquid catalysts. The reaction pathway for benzene alkylation remains uncertain with disagreement in the literature in regards to the preferred pathway. This work will combine kinetic, spectroscopic, and theoretical methods to identify the kinetic relevance of elementary steps in the reaction pathways in order to analyze rate parameters. In addition, we will look at the impact that microporous structures in zeolites have on the reactivity, selectivity, and stability of the transition state that leads to the desired products. These results can be utilized to improve the efficiency of benzene alkylation as well as assist with future catalytic process design.