Researchers from MIT have reported a simple technique that uses small amounts of energy could boost the efficiency of some key chemical processing reactions. These reactions are crucial for industries such as petrochemical processing and pharmaceutical manufacturing.
The MIT researchers behind the study found that this technique could boost the efficiency of these reactions by up to a factor of 100,000.
The study reports a significant increase in reaction rates, which is unusual for reactions that don’t involve oxidation or reduction. According to Yogesh Surendranath, a chemistry and chemical engineering professor, such rate increases have been observed before, but in a different type of catalytic reaction known as redox half-reactions, which involve the gain or loss of an electron.
The non-redox chemical reactions studied by the MIT team are catalyzed by acids. “If you’re a first-year chemistry student, probably the first type of catalyst you learn about is an acid catalyst,” Surendranath says. There are hundreds of such acid-catalyzed reactions, “and they’re super important in everything from processing petrochemical feedstocks to making commodity chemicals to transforming pharmaceutical products. The list goes on and on.”
“These reactions are key to making many products we use daily,” adds Roman-Leshkov, a professor of chemical engineering and chemistry.
Researchers who study redox half-reactions, also known as electrochemical reactions, are part of an entirely different research community than those studying non-redox chemical reactions, known as thermochemical reactions.
The technique used in the new study, which involves applying a small external voltage, is commonly known in the electrochemical research community. However, it had not been systematically applied to acid-catalyzed thermochemical reactions.
Surendranath says people working on thermochemical catalysis usually don’t consider the role of the electrochemical potential at the catalyst surface, and they often lack the proper tools to measure it. The study shows that even small changes in electrochemical potential can have significant impacts on catalyzed reactions at the surface of the catalyst.
According to researchers, the chemical binding energy of molecules to active sites on the surface is what affects the energy needed for the reaction. However, a recent study suggests that the electrostatic environment is equally important in defining the rate of the reaction. The team has filed a patent application and is working on applying the findings to specific chemical processes. They believe that different types of reactors can be designed and developed to take advantage of this strategy. The team is currently working on scaling up these systems.
While the experiments conducted thus far have used two-dimensional planar electrodes, in industrial settings, most reactions are carried out in three-dimensional vessels filled with powders. This is because using powders provides a much larger surface area for the catalysts to be distributed, allowing for more efficient and effective reactions.
“We’re looking at how catalysis is currently done in industry and how we can design systems that take advantage of the already existing infrastructure,” MIT graduate student Karl Westendorff says.
Surendranath adds that these new findings “raise tantalizing possibilities: Is this a more general phenomenon? Does electrochemical potential play a key role in other reaction classes as well? In our mind, this reshapes how we think about designing catalysts and promoting their reactivity.”
While there has typically been little interaction between electrochemical and thermochemical catalysis researchers, Surendranath says, “This study shows the community that there’s really a blurring of the line between the two and that there is a huge opportunity in cross-fertilization between these two communities.”
In practice, the team says the findings could lead to far more efficient production of a wide variety of chemical materials. “You get orders of magnitude changes in rate with very little energy input,” Surendranath says. “That’s what’s amazing about it.”
The findings, he says, “build a more holistic picture of how catalytic reactions at interfaces work, irrespective of whether you’re going to bin them into the category of electrochemical reactions or thermochemical reactions.” He adds that “it’s rare that you find something that could really revise our foundational understanding of surface catalytic reactions in general. We’re very excited.”
“This research is of the highest quality,” says Costas Vayenas, a professor of engineering at the University of Patras in Greece, who was not associated with the study. The work “is very promising for practical applications, particularly since it extends previous related work in redox catalytic systems,” he says.
Journal reference:
- Karl S. Westendorff, Max J. Hülsey, Thejas S. Wesley, Yuriy Román-Leshkov, Yogesh Surendranath. Electrically driven proton transfer promotes Brønsted acid catalysis by orders of magnitude. Science, 2024; DOI: 10.1126/science.adk4902