The Division of Chemistry supports Thomas Lyons of the University of North Carolina at Chapel Hill as an American Competitiveness in Chemistry Fellow. Dr. Lyons will develop new transition metal-containing catalysts for transfer dehydrogenation of alkanes, using molecular oxygen as a hydrogen acceptor. He will collaborate with scientists at Eastman Chemical to develop the methodology in a process-chemistry environment. For his plan for broadening participation, the PI will work with colleagues at the Morehead Planetarium and Science Center and LearnNC to develop high-school curriculum materials that illustrate the role of catalysts in chemistry. Many of the students served in this project will come from economically disadvantaged communities.
Research like that of Dr. Lyons is aimed at developing better routes for the synthesis of pure chemical compounds. These chemicals are ultimately used in consumer products as well as in pharmaceuticals. The particular methods that Dr. Lyon is developing are "green" in that they use environmentally benign reagents (oxygen) and produce relatively benign waste (water). In addition, the processes developed should use significantly less energy than current high-temperature methods used in industry today. The hope is to develop more sustainable ways to produce the chemical compounds that modern society depends upon. The efforts at broadening participation being pursued by Dr. Lyon are aimed at giving economically disadvantaged students in North Carolina (and beyond) exposure to real-world examples of important chemical phenomena with the goal of increasing the participation of talented students from these groups in the technological workforce.
This project has investigated new methods for the efficient conversion of crude oil feedstocks to important commoditiy chemicals utilized in many aspects of daily life. As our crude oil supplies diminish, we will need to develop more efficient methods to convert these supplies to the goods we use regularly. Ideally, these methods would be versatile enough to utilize new feedstocks from renewable resources and/or recently discovered domestic shale gas reserves. Thus, we have sought to invent new catalysts to convert simple alkanes to more valuable products such as para-xylene, which is used to create PET plastics found in plastic bottles, textiles, and medical supplies. The investigation of these approaches may lead to more economically and energy efficient uses of current and future oil supplies. Traditionally, alkanes derived from crude oil are heated at high temperatures or 'cracked' to convert them to more useful alkenes and aromatics. This process eliminates hydrogen in a net dehydrogenation.The high temperatures involved make these processes nonselective and require further distillation and separation techniques to obtain pure products. We have been investigating new classes of catalysts that are able to achieve the same reactivity at much lower temperatures. To accomplish this transformation, a hydrogen acceptor must be used to 'trap' the hydrogen generated, resulting in a transfer dehydrogenation. Previous work has demonstrated this is possible but, the acceptor used is quite costly. Through this work we have developed a catalyst that can use ethylene, a cheap and readily available molecule, as a hydrogen acceptor. This greatly improves the efficiency and applicability of this process. As part of these investigations we have discovered a new application of this transfer dehydrogenation reaction with ethylene. Combined with other known reactions, transfer dehydrogenation with the catalyst investigated in this work can be used to generate para-xylene using only ethylene gas as the sole starting material. Importanly ethylene can be generatred from renewable sources such as ethanol or from domestic shale gas reserves. To improve the potential for other applications of these catalyts we have synthesized new derivatives that can be attached to a solid surface rather than dissolved in solution. This will greatly enable the separation of the catalysts from the reactants and products being consumed and generated. This will allow the catalyst to be recycled more easily for future reactions. Investigations are ongoing to make more reactivie catalysts of this type as well as to find new applications for the aforementioned discoveries.
