Scientists have uncovered an affordable method to reduce pollution from hydrogen internal combustion engines by enhancing the effectiveness of their catalytic converters. Their research indicates that adding platinum to catalytic converters, combined with a highly porous substance known as Y zeolites, significantly boosts the chemical interactions between nitrogen oxides and hydrogen. This process transforms harmful nitrogen oxides into harmless nitrogen gas and water vapor.
Hydrogen-powered internal combustion engines hold great potential in combating climate change since they deliver robust power without releasing carbon that contributes to global warming.
They are capable of operating heavy-duty trucks and buses and are ideal for agricultural machinery and back-up generators, providing cleaner alternatives to traditional diesel engines.
However, they are not completely eco-friendly, as they release nitrogen oxides during their hot combustion processes. These nitrogen oxides can interact with other atmospheric compounds to create dangerous ozone and fine particulate pollution, which can harm respiratory health and cause chronic illnesses.
Fortunately, scientists from UC Riverside have identified a cost-efficient technique to reduce pollution from hydrogen engines by improving the performance of their catalytic converters.
According to findings published in the journal Nature Communications, the research team observed that incorporating platinum with Y zeolites significantly boosts the conversion of nitrogen oxides and hydrogen into harmless substances like nitrogen gas and steam.
The study revealed that, at a temperature of 250 degrees Celsius, the rate of nitrogen oxides conversion to non-harmful products increased by four to five times when using zeolites compared to conventional catalytic converters. This new system was particularly effective at lower temperatures, which is vital for minimizing pollution when engines are initially started and still cool.
Additionally, this innovative technology could help decrease emissions from diesel engines that use hydrogen injection systems, as explained by Fudong Liu, the lead author and associate professor of chemical and environmental engineering at UCR’s Bourns College of Engineering. The hydrogen injection process would resemble that of selective catalytic reduction systems utilized in large diesel trucks.
Zeolites are cost-effective materials with a unique crystalline arrangement primarily made up of silicon, aluminum, and oxygen. Their expansive surface area and three-dimensional cage-like structure make them efficient in breaking down pollutants.
By combining platinum and Y zeolite—a synthetic variant of the broader zeolite family—the researchers created a system that captures the water produced during hydrogen combustion. This water-rich environment fosters hydrogen activation, which is critical for enhancing the efficiency of nitrogen reduction.
Shaohua Xie, a research scientist at UCR and the lead author of the study, noted that while zeolite itself isn’t a catalyst, it considerably improves the effectiveness of the platinum catalyst by creating a water-rich environment. This theory was further supported by theoretical modeling conducted by Ph.D. student Liping Liu and Hongliang Xin, an associate professor at Virginia Tech.
“This method can also be applied to different types of zeolites,” Xie mentioned. “It’s a versatile approach.”
Liu highlighted that the approach to reducing pollution is quite straightforward.
“We don’t require complicated chemical or physical processes,” Liu stated. “We simply blend the two materials—platinum and zeolite—conduct the reaction, and witness improved activity and selectivity.”
UCR’s Liu, Xie, and Kailong Ye mixed Y zeolite and platinum powders and shared them with collaborating scientist, Yuejin Li at BASF Environmental Catalyst and Metal Solutions (ECMS) in Iselin, New Jersey. The mixture was transformed into a viscous liquid slurry, enhanced with binding agents, and applied to the honeycomb structures of prototype catalytic converters. They also collaborated with scientists from the National Synchrotron Light Source II (NSLS-II) at Brookhaven National Laboratory in Upton, New York.
Liu and Xie anticipate that BASF, the study’s financial backer, will commercialize this technology, which is currently the subject of a pending patent.
“We take pride in our work,” Xie said. “We’ve engineered a new technology aimed at controlling nitrogen oxide emissions, and we believe it’s an impressive solution.”
