University Of Minnesota Discovers Selective Combustion Method

In a pioneering breakthrough, scientists at the University of Minnesota Twin Cities have created a technique that has the potential to transform industrial processes by selectively combusting one molecule from a mixture of hydrocarbons. This technology has the potential to increase the production of fuels, plastics, medicines, and fertilizers and make energy more efficient while lowering emissions.

The research, which was released in Science, explains how researchers used a bismuth oxide catalyst to burn acetylene selectively from a mixture of ethylene. The achievement solves a long-standing problem in chemical processing—eliminating trace impurities without harming the remainder of the mixture. Having the ability to remove acetylene effectively is especially important when making polyethylene plastics, which are used for everything from packaging materials to medical equipment. With a worldwide market of over 120 million metric tons a year, even incremental gains in efficiency have substantial economic and environmental impact.

The researcher, Aditya Bhan, who is a Distinguished McKnight University Professor in the Department of Chemical Engineering and Materials Science and senior author of the study, highlighted the uniqueness of this strategy. No other group has demonstrated that you can burn one hydrocarbon in low concentrations using mixtures of others," he said. Conventionally, combustion means that complete fuel mixtures are combusted in high temperatures to produce heat. But through this new technique, scientists have been able to target and eliminate certain molecules more selectively, which enhances efficiency and cuts energy use.

The secret to this breakthrough is the special properties of the bismuth oxide catalyst. In contrast to traditional catalysts that need an external source of oxygen, bismuth oxide supplies its own oxygen through a process called chemical looping. This reaction is self-sustaining and allows for repeated oxygen extraction and replenishment within the catalyst, keeping it reactive over many cycles. "We could extract oxygen from the catalyst and reinsert it several times, where the catalyst is slightly altered, but its reactivity is not affected," said Matthew Jacob, a Ph.D. candidate in chemical engineering at the University of Minnesota and lead author of the paper. He added that running in this chemical looping mode also reduces flammability issues, making the process safer.

Removing small amounts of impurities has long been a hindrance in industrial chemistry. Conventional processes tend to be energy-hungry and involve either extreme temperatures or high concentrations of reactants to effect the necessary purification. This new catalytic method, however, is much more energy-efficient. "You want to do this process selectively," stated Matthew Neurock, a Department of Chemical Engineering and Materials Science professor and the study's senior co-author. "Removing trace hydrocarbon contaminants such as acetylene could be more efficient energy-wise. You simply want to be able to go into a mixture of gases to remove some molecules without coming into contact with the other molecules."

The relevance of this discovery goes far beyond hydrocarbon cleanup. Catalysts are a critical component of industry today, controlling the manufacture of millions of chemicals and materials. By learning the way molecules respond to catalyst surfaces at the atomic level, scientists can create better catalysts with specific applications. This could unlock new technologies across a range of industries, from refining biofuels to creating pharmaceuticals.

Simon Bare, a Distinguished Scientist at the SLAC National Accelerator Laboratory at Stanford University and co-author of the research, pointed to the wider implications of this work. "If we can figure out how a catalyst functions, at a molecular atomic level, we can apply it to any given reaction," he explained. "This can lead us to comprehend how catalysts, which produce fuels and chemicals required in contemporary living, respond to their environment."

The research was carried out by a group of researchers from the University of Minnesota Department of Chemical Engineering and Materials Science, including graduate students Rishi Raj and Huy Nguyen, Professor Andre Mkhoyan, and Javier Garcia-Barriocanal from the University of Minnesota Characterization Facility. Other collaborators were Jiyun Hong, Jorge E. Perez-Aguilar, and Adam S. Hoffman from the SLAC National Accelerator Laboratory at Stanford University.

This study was funded by grants from the U.S. Department of Energy, Office of Basic Energy Sciences. The research was conducted in collaboration with the University of Minnesota Characterization Facility and the Minnesota Supercomputing Institute.

By providing new insights into selective combustion and catalytic reaction, this research represents a crucial step toward more efficient and sustainable industrial processes. At scale, this discovery could result in cleaner production, less energy usage, and a less environmentally impactful future for industries that depend on hydrocarbon processing.