Controlling Selectivity of Photocatalytic Activation of Methane for Coupling Products using Pulsed Illumination

Natural gas, which is mostly methane, is one of the most abundant natural resources in the U.S. However, methane is relatively unreactive. Turning methane into useful chemicals without creating unwanted waste is challenging. Efficient methane conversion could lower the price of chemicals, reduce pollution, and support cleaner industrial processes. This will project study how light can guide chemical reactions to turn methane directly into valuable products with minimal waste. The researchers will test a new method using short bursts of light to steer the reaction toward the desired products. The project will enable cleaner and more efficient ways to make fuels and chemicals from natural gas. The work will also strengthen workforce development through partnerships with local schools. The team will run workshops for high school students and provide mentoring through a long standing educational program. This project will investigate the photocatalytic coupling of methane and carbon monoxide to form acetone, a three carbon oxygenate. The goal will be to address the selectivity challenge that arises because conditions required to generate activated methane (*CH3) also promote overoxidation to carbon dioxide. To solve this issue, the researchers will employ a strategy based on the temporal modulation of illumination, beginning with short, intense light pulses that produce photogenerated charges and a transient high population of *CH3, followed by low light intervals that suppress further charge formation and allow thermocatalytic coupling of the intermediates to proceed. This approach will parallel stopped flow concepts but will leverage the unique tunability of light intensity across wide timescales. The project will advance the fundamental understanding of how dynamic stimuli control intermediate concentrations in catalytic systems. This understanding may extend to other reactions, including dry methane reforming. More broadly, the project outcomes will contribute to catalysis, surface chemistry, and chemical engineering by demonstrating a new mechanism for steering reaction pathways through controlled, time dependent illumination. 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.