Promising New Membrane Traps Greenhouse Gases

Japanese researchers have developed a finely porous membrane that can trap greenhouse gases but lets clean air pass through.

The work at Kyoto University’s Institute for Integrated Cell-material Sciences (iCeMS) is still in the early stages, but the membrane may one day provide a fairly simple way to clean the Earth’s atmosphere with a sturdy, inexpensive device.

Many nations already are looking for ways to reduce their emissions of greenhouse gases, which trap heat in the atmosphere and are believed to be responsible for global warming. These gases are made up mostly of carbon dioxide, which can linger in the air for thousands of years. In 2012, CO2 made up 84 percent of the greenhouse gases emitted in the United States.

If carbon dioxide were somehow useful, it could be trapped and recycled. But so far it’s shown to be nothing more than waste that’s expensive to neutralize. As a result, the inexpensive iCeMS membrane may be the answer.

A paper on the research has been published in the scientific journal Nature Communications.

Scientists from iCeMS, under associate professor Easan Sivaniah, teamed up with colleagues from the University of Cambridge to develop the membrane, which they call PIM-1. Qilei Song said the membrane is “typically embedded with a network of channels and cavities less than 2 nm [nanometers] in diameter that can trap gases of interest once they enter.”

Yet there’s a problem, Song says: “[T]heir intrinsic properties make them rather flimsy.”

So Sivaniah’s team turned to a process known as thermal oxidation, in which the PIM-1 membrane was heated at temperatures between 250 and 850 degrees Fahrenheit. Song explains that the heating is done in the presence of oxygen, which under high temperatures not only strengthens the channels but also controls the “gate openings” of cavities.

The researchers found that thermal oxidation effect on the cavities made them capable of trapping twice as much carbon dioxide as before thermal oxidation treatment. Further, the cavities now allowed clean air to pass through them 100 times faster than it can through commercially available alternatives.

The PIM-1 membrane can be used to capture carbon dioxide from the fossil fuel combustion to enrich oxygen content in air to make combustion engines more efficient, generate plastics, and produce clean-burning hydrogen gas.

“Basically, we developed a method for making a polymer that can truly contribute to a sustainable environment,” Sivianah said in an interview published by EurekAlert. “And because it is affordable and long-lasting, our polymer could potentially cut the cost of capturing carbon dioxide by as much as 1,000 times.”

Sivianah’s work isn’t the only research into materials to trap greenhouse gases before they foul the air. Scientists at the University of Liverpool reported in August that they’ve developed a micro porous “sponge” that can also do the job, and that it, too, is strong and stable.  

By Andy Tully of Oilprice.com