Developing Late Metal Catalytic Systems for Aerobic Partial Oxidation of Alkanes

With the support of the Chemical Catalysis and the Chemical Structure, Dynamics, and Mechanism B Programs in the Division of Chemistry, Professor Karen Goldberg of the University of Pennsylvania is studying the development of catalysts that will promote the selective conversion of natural gas to useful chemicals. Methane, the largest component of natural gas, is a significant contributor to climate change. Currently large amounts of natural gas are flared (burned without energy capture to produce carbon dioxide and water) because methane is a more potent greenhouse gas than carbon dioxide, and it is not profitable to transport it as a gas or convert it onsite to a liquid. The researchers on this project are working to design metal compounds that will act as catalysts to directly convert natural gas to higher-value products under mild conditions using the oxygen in air. Detailed studies of the selective cleavage and formation of key chemical bonds by specific metal compounds will be carried out to determine the important design principles for these catalysts. With a strong emphasis on increasing diversity in science, this project is also training graduate students and providing them with the research skills needed to creatively address future challenges facing society. Transition metal complexes have shown a unique ability to selectively activate the C-H bonds of alkanes. However, many of these selective C-H bond cleavage reactions are not viable in the presence of air or oxygen. This condition presents an impediment to the development of technologies to carry out the selective partial oxidation of alkanes on a large scale, where oxygen is considered the most promising oxidant. This project targets the development of transition metal complexes that can selectively activate and functionalize C-H bonds using air or oxygen as the oxidant. The researchers on the Goldberg team will explore new mechanisms for the activation of alkane C-H bonds that proceed in the presence of oxygen and water. Detailed mechanistic studies of the reactions of metal alkyl and hydride complexes, the products of alkane C-H activation, with oxygen will be carried out to learn how to incorporate oxygen as the oxidant in natural gas upgrading. Students involved in these activities will learn synthetic skills and a hypothesis-driven mechanistic approach to catalyst discovery and optimization, while participating in outreach activities and being encouraged to participate in broadening inclusive thinking in chemistry. 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.