ABQ Times

A recent study published in the journal Nature reveals a serendipitous discovery that may enhance catalyst efficiency significantly. An international team of researchers, including members from Washington State University, Pacific Northwest National Laboratory, The University of New Mexico, the University of Sofia in Bulgaria, and Purdue University, uncovered that hot car exhaust comprised of nitrogen oxides and carbon monoxide triggered an unexpected reaction in ceria nanoparticles. This revelation holds potential to cut down on the usage of rare and expensive metals in vehicle catalytic converters and other industrial processes.

The researchers observed that ceria (cerium oxide) particles formed two-dimensional, nano-sized clusters under high temperatures, thereby increasing reaction sites and improving catalytic efficiency. "When we first started this work, we found ceria to be present in the form of nanoparticles, but when we studied the same catalysts using aberration-corrected electron microscopy, we learned there were single atoms of cerium all over the alumina surface," explained University of New Mexico Distinguished Regents Professor Emeritus Abhaya Datye, one of the study’s corresponding authors. The finding showed that cerium ions could spread to form either nanoparticles or two-dimensional patches.

A related benefit discovered was the creation of loosely bound oxygen ions associated with cerium atoms. These ions improve reactions requiring oxygen. Yong Wang, a corresponding author and Regents Professor at the Gene and Linda Voiland School of Chemical Engineering and Bioengineering at Washington State University, stated, "They act like an oxygen sponge, and once the oxygen is easily activated, it’s very useful for many reactions requiring oxygen, like oxidation of hydrocarbons and carbon monoxide."

The improved method surprisingly boosts catalytic activity tenfold. "Luck was a factor in this. Sometimes, we just stumble into a great science discovery. At the same time, this is one which is of practical interest,” confirmed Wang, who also holds a position with Pacific Northwest National Laboratory.

Research indicates that hot exhaust can aid catalytic efficiency by dispersing ceria particles, contradicting assumptions that it would cause degradation. Pacific Northwest National Laboratory's Konstantin Khivantsev noted, "There is a process that was not discovered or recognized, but it contributed to improved dispersion and catalytic activity."

By intentionally simulating the exhaust's impact, the researchers improved the catalyst's effectiveness rather than its degradation. Datye remarked, "So, this is part of the fun of doing research because intuition told us that the catalyst would de-activate, and the results were the complete opposite.”

As a practical step forward, the team aims to deliberately apply this technique to simultaneously pre-activate the catalyst and form a reactive state. Such a process could reduce the need for precious metals like rhodium in catalysts, which could lower costs.

János Szanyi, a staff scientist at PNNL, added, "In the spent catalysts, atomically thin patches of ceria that formed during the dispersion of ceria nanoparticles, are in contact with precious metals, such as rhodium and platinum."

Currently, the team is testing catalyst treatments in lab conditions, with plans to expand testing in real vehicles. This research has been supported by the U.S. Department of Energy’s Office of Science under its Catalysis Science program, and the U.S. Department of Energy’s Energy Efficiency and Renewable Energy Vehicle Technologies Office also aided the study conducted at PNNL.