Stony Brook University researchers working at the U.S. Department of Energy’s Brookhaven National Laboratory (BNL) have developed a new theoretical framework for more accurately predicting the behavior of catalysts. These collections of atoms lower the energy needed for countless chemical reactions. The study reveals how conditions such as temperature and pressure can change a catalyst’s structure, efficiency, and even the products it makes. The findings are published in the journal Chem Catalysis.
“Our results highlight the significant impact the reaction environment can have on catalytic performance,” said Ping Liu, a theorist in BNL’s chemistry division who is also an adjunct professor at Stony Brook and oversaw the research. “We show that these catalyst-environment interactions can be used to tune the efficiency and selectivity of catalysts, which could point to new ways to design better catalysts.”
For the study, the scientists modeled catalysts that help hydrogen (H2) convert carbon dioxide (CO2), a greenhouse gas, into a range of other products, including methanol. The catalysts were made of palladium (Pd) partnered with other metals — zinc (Zn) or silver (Ag) — that scientists had previously shown to be effective for the “CO2 hydrogenation” reaction.
They were motivated by a big discrepancy in earlier research on this reaction. In previously published experiments, metallic palladium preferentially produced formic acid (HCOOH). But theoretical calculations predicted that methanol (H3COH) should be the most energetically favorable product.
“This contradiction between theory and experiment made us wonder why there are differences. What are we missing?” Liu asked.
Hong Zhang, Liu’s graduate student at SBU and the first author on the paper, designed a way to find out by modeling what happens during the reaction.
“We developed a framework based on density function theory and kinetic modeling to capture the dynamic behavior and structure of the catalyst under operational reaction conditions,” Zhang said.
“The reality is that a catalyst often undergoes significant structural changes or phase transitions in the reaction environment,” Liu said. “But those reaction-driven dynamics are difficult to capture experimentally at the atomic level, even using the amazing characterization tools we have for studying catalysts in real time.”
Read the full story at the BNL website.
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