A research team at the U.S. Department of Energy's Brookhaven National Laboratory has developed a new catalyst for converting ethanol into acetaldehyde, a compound used in the manufacture of resins, dyes, perfumes and synthetic flavors. The new system works faster, produces less waste and lasts longer than existing metal catalysts, according to Phys.org.
Acetaldehyde is typically made using petrochemical processes. Ethanol, by contrast, can be produced from biomass sources such as food waste, crop residues and forestry byproducts, making the ethanol-based route more sustainable. The challenge has been finding a catalyst that can handle the conversion efficiently without breaking the ethanol down too far or losing effectiveness over time.
The new catalyst is unusual because it uses three metals instead of the one or two metals typical in thermal catalysis, where heat drives the reaction. The system combines platinum, chromium and silver. The platinum and chromium atoms pair together in dumbbell-like structures, which the researchers call dimers, while silver serves as the bulk host material surrounding them.
"Our catalyst solves an important problem in chemistry because it completes a selective dehydrogenation: Instead of stripping away all of the hydrogen atoms, it removes just the ones necessary," said chemist Anatoly Frenkel, who holds a joint appointment with Brookhaven and Stony Brook University and co-led the paper, which appears in the journal Angewandte Chemie.
The selective nature of the reaction is what sets this catalyst apart from copper and nickel-based alternatives, which tend to either clump together or break ethanol down too aggressively. Both problems reduce the quality and yield of the final product.
Frenkel explained why this class of three-metal catalyst has received little attention until now. "Systems like this one, in which two different metals form a 'dimer' structure like our dumbbells, supported by a bulk third metal, tend to have broader functionality and greater stability — each metal takes on a different key role," he said. "But they have not been well explored, and detecting the dimers and studying those roles is exceedingly difficult."
To understand how the system behaves, the team used theoretical modeling, electron microscopy and X-ray techniques at two synchrotron facilities: Brookhaven's National Synchrotron Light Source II and the MAX IV synchrotron laboratory in Sweden. The theoretical work guided the experimental investigation, helping the team predict what structures to look for before they could be directly observed.
The collaboration involved Brookhaven researchers and international scientists. The work points toward a broader class of trimetallic catalysts that could find applications beyond ethanol dehydrogenation, though the team's published findings focus on this specific reaction.
