As the world’s accessible oil reserves dwindle, natural gas has become an increasing important energy source. The primary component of natural gas is methane, which has the advantage of releasing less carbon dioxide when it’s burned than do many other hydrocarbon fuels. But because of the very stable structure of the methane molecule, it can be difficult to access the energy stored within. When unburned methane escapes into the atmosphere, it’s a greenhouse gas 20 times more powerful than carbon dioxide.
Now, researchers from the University of Pennsylvania , along with collaborators from Italy and Spain, have created a material that catalyzes the burning of methane 30 times better than do currently available catalysts.
The discovery offers a way to more completely exploit energy from methane, potentially reducing emissions of this powerful greenhouse gas from vehicles that run on natural gas. The catalyst may also offer a cleaner and cheaper way of generating energy from catalytic combustion in gas turbines.
"It’s hard to come up with materials that are active enough and stable enough to withstand the harsh conditions of methane combustion," said Raymond J. Gorte , the Russell Pearce and Elizabeth Crimian Heuer Professor in Penn’s Department of Chemical and Biomolecular Engineering. "Our materials look promising for some important applications."
Matteo Cargnello , now a postdoctoral fellow in Penn’s Department of Chemistry , joined Gorte and Kevin Bakhmutsky, a former Ph.D. student in Gorte’s lab, in the study. Their collaborators included Paolo Fornasiero and Tiziano Montini of Italy’s University of Trieste and National Research Council and José J. Calvino , Juan José Delgado and Juan Carlos Hernández Garrido of the Universidad de Cádiz in Spain. The study is published .
Cargnello began work on this project while still an undergraduate at the University of Trieste, during a visit to Gorte’s laboratory, and continued the collaboration as he pursued his doctoral degree at the Graduate School of Nanotechnology at the University of Trieste.
Catalysts are materials that make a chemical transformation quicker, easier, more energy-efficient and often safer. A car’s catalytic converter, for example, transforms exhaust gases into innocuous products.
Catalysts that are currently available to burn methane, however, do not do so completely, leaving unburned methane to escape into the atmosphere and contribute to climate change.
"Particularly if you have a natural-gas engine, methane is going to be a major part of that tailpipe exhaust," Gorte said.
In addition, these conventional catalysts can require high temperatures of 600-700 degrees Celsius to encourage reactions to move along. Yet the catalysts themselves often lose their efficiency or deactivate when exposed to the high temperatures generated by methane combustion.