Zeolites Effective in Trapping Methane: Study

Researchers have discovered a material - zeolite - that can trap methane, a greenhouse gas that is associated with rising global temperatures.

The material was discovered by scientists from Lawrence Livermore National Laboratory (LLNL) and UC Berkeley.

Methane is the second most prevalent greenhouse gas in the environment, according to Environmental Protection Agency. And although methane's lifetime is shorter than carbon dioxide, it can trap more heat. Major sources of methane include natural gas and petroleum systems, wastewater treatments, agriculture and coal mining.

A recent study from the journal Nature Climate Change found that reducing emissions of common pollutants like soot, methane and refrigerants could reduce global warming over the next 100 years.

Carbon dioxide can be captured and fixed by using physical materials and chemical reactions. However, methane is non-polar and interacts weakly with other materials, making its capture difficult.

"Methane capture poses a challenge that can only be addressed through extensive material screening and ingenious molecular-level designs," Amitesh Maiti from Lawrence Livermore National Laboratory, Livermore, said in a news release.

For the study, researchers screened nearly 100,000 zeolites structures and found that some of these nonporous structures could be potentially used to trap the gas on a large scale.

Zeolites are hydrated aluminosilicates of the alkaline and alkaline-earth metals. These materials are used in pet litter boxes, horticulture and treating wastewater.

In the present study, a zeolite called SBN trapped medium source methane and turned it into pure methane. Now, the gas is a good source of energy, so pure methane can be used to generate electricity. Other zeolites such as ZON and FER were also found to be effective in concentrating dilute methane stream to moderate concentrations of the gas. These zeolites could be used to obtain methane from coal-mine ventilation air.

"We used free-energy profiling and geometric analysis in these candidate zeolites to understand how the distribution and connectivity of pore structures and binding sites can lead to enhanced sorption of methane while being competitive with CO2 sorption at the same time," Maiti said.

The study is published in the journal Nature Communications.