A Rice University-led team has unveiled how tiny molecular structures on industrial catalysts behave during the manufacture of vinyl acetate monomer (VAM), a core ingredient in adhesives, paints, coatings, packaging, textiles and many other products people use every day.
By revealing how these molecular palladium-acetate trimers and dimers transform under reaction conditions and control catalyst performance, the work points the way to catalyst designs that could cut energy use, reduce carbon emissions and make global VAM production cleaner and more reliable.
"Vinyl acetate underpins a huge slice of the modern materials economy, so small efficiency gains can translate into major environmental and economic benefits," said Michael Wong , corresponding author of the study, the Tina and Sunit Patel Professor in Molecular Nanotechnology and professor of chemical and biomolecular engineering at Rice. "By understanding how these palladium-acetate species behave, we can help industry design catalysts that use less energy, generate less waste and deliver more stable production over the long term."
The study, published in Nature Communications , was carried out in collaboration with Celanese Corp., a global leader in VAM production, along with partners at Purdue University and Oak Ridge National Laboratory.
VAM is produced by reacting ethylene, oxygen and acetic acid over a palladium-gold catalyst promoted with potassium acetate. The researchers created simplified palladium-acetate model catalysts and followed them under realistic reaction conditions using advanced X-ray, spectroscopic and electron microscopy techniques coupled with computational modeling.
They showed that potassium acetate stabilizes specific palladium-acetate dimers and alters how they convert into metallic palladium nanoparticles. When those nanoparticles stay small and well dispersed, the catalyst becomes both more active and more selective for VAM, reducing wasteful side reactions that burn valuable feedstocks into carbon dioxide.
"We found that by tuning these molecular species, you can dramatically change how the catalyst uses energy and how much valuable product you get for every molecule you put in," said Hunter Jacobs , co-first author and Rice doctoral alumnus now at Oak Ridge National Laboratory. "That's exactly the kind of insight that can help industry lower operating temperatures, cut emissions and stretch resources further."
Co-first author Welman Curi-Elias , a research scientist in chemical and biomolecular engineering at Rice, said the work reframes how chemists think about these species.
"These trimers and dimers were often treated as inactive species or signs of deactivation," Curi-Elias said. "Our results show they are dynamic players in a redox cycle that controls nanoparticle size and ultimately how efficiently and cleanly vinyl acetate is made."
Improved catalysts for VAM could deliver a range of benefits, including lower energy consumption in large-scale chemical manufacturing, less material waste and greenhouse gas emissions, longer-lasting industrial equipment thanks to more stable catalyst behavior and more stable pricing and supply of essential materials used in consumer goods.
"Every gain in selectivity means less raw material burned off as carbon dioxide and more of it ending up in useful products," Wong said. "That's good for the climate, for manufacturers and for the people who rely on these materials every day."
For Celanese, which operates major VAM production facilities, the findings offer a science-based road map for more sustainable manufacturing.
"This research helps us see exactly how to push catalysts toward higher efficiency and longer life," said Kevin Fogash, senior director of process technology for Celanese. "If we can produce the same amount of vinyl acetate using less energy with less waste and fewer shutdowns, that benefits our customers, our communities and the environment. It also supports more predictable supply and pricing for the many industries that depend on these materials."
The team's computational work showed that multiple palladium-acetate species can actively form vinyl acetate but that their true importance lies in how they signal and shape nanoparticle growth. In other words, these molecular complexes serve as sensitive indicators of catalyst health and guides for how to design next-generation systems.
"What excites us is that we now have a molecular-level picture that ties directly to metrics industry cares about: efficiency, stability and environmental footprint," Wong said.
This research was supported by Celanese, the ACS Petroleum Research Fund and the U.S. Department of Energy.
