Developing homogeneous catalytic systems for aerobic oxidative methylation with methane

University Of Maryland, College Park, College Park MD

Investigators

Abstract

With funding from the Chemical Catalysis Program of the Division of Chemistry, Dr. Andrei Vedernikov of the University of Maryland College Park is developing novel platinum catalysts that convert methane from natural gas to high value-added chemicals. Oxygen from the air is used as a reactant and so these reactions avoid expensive and potentially toxic reagents Water is the major reaction by-product, so there is little waste produced. Methane is known for its chemical inertness and the development of greener processes for its economically-viable conversion to high-value added products is a fundamental chemical challenge. To tackle this problem, Dr. Vedernikov is studying novel platinum catalysts and designing new catalysts. He is taking advantage of theoretical and computational chemistry to explore plausible reaction pathways and guide his catalyst designs and experimental work. Dr. Vedernikov is working with high school students from low-income families. These students are interested in chemistry and have been selected by the local Washington D.C. section of the American Chemical Society (ACS Project SEED). The students intern in his lab, contributing to the experimental work in this project. Dr. Vedernikov is studying Shilov-type systems wherein electrophilic Pt(IV)Me intermediates are generated using O2 as the oxidant. Two complementary experimental approaches are used in this work. One relies on the use of redox mediators, e.g., Cu(II), while another utilizes a ligand-enabled O2 activation by Pt(II)R intermediates. The electrophilic Pt(IV)R intermediates are then intercepted by various nucleophiles (carboxylic acids, amines, etc.) to form hydrocarbon derivatives, such as quaternary ammonium salts or esters, that are protected from further oxidation. Dr Vedernikov is developing a fundamental mechanistic understanding of how the ligand environment at the Pt(II) center enables and tunes its reactivity toward both the hydrocarbon C-H bonds, and O2 to generate the Pt(IV)R intermediates. The viability of both approaches has been recently demonstrated in Dr. Vedernikov's group. Density functional theory is being used to guide the design of these novel systems and to carry out mechanistic analyses. The development of more efficient and environmentally benign protocols for methane functionalization is transformative. As a part of the broader impacts, Dr. Vedernikov is working with and training local high school, undergraduate and graduate students in this project. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.