New materials are capable of capturing selective carbon dioxide

UCLA chemists have announced a major step forward in reducing heat-trapping carbon dioxide emissions on February 15 in Science .

Scientists have proven they have succeeded in sequestering and retaining carbon dioxide - a gas that contributes to global warming, rising sea levels and increasing acidity levels in large positive. The finding led to power plants efficiently capturing carbon dioxide without using toxic materials.

"The technical challenge in choosing to remove carbon dioxide has been overcome," said Omar M. Yaghi, UCLA professor Christopher S. Foote and co-author of the Science article. 'We now have structures that can correctly respond to the removal of carbon dioxide and hold as a reservoir. No carbon dioxide escapes. Nothing comes out - unless you want to. We believe this is a turning point in removing carbon dioxide before they get into the atmosphere. '

Carbon dioxide is captured by a new material designed by Yaghi and colleagues called zeolitic imidazolate, or ZIF . These are sophisticated chemical structures and have honeycomb-shaped holes, with a large surface, which can be heated at high temperatures without being decomposed and heated in water or organic solvents for a week. without being changed.

Rahul Banerjee - UCLA's postdoctoral chemistry researcher and UCLA chemistry graduate student Phan both worked at Yaghi's lab, synthesized 25 ZIF crystal structures. and demonstrate that 3 of them are highly selective in carbon dioxide capture ( ZIF-68, ZIF-69, ZIF-70 ).

ZIF . (Photo: UCLA)

'The selective feature of ZIFs for carbon dioxide is no other material that can be matched', Yaghi said (he is the director of UCLA center for intensive chemistry and also a member of the Institute of Technology California Nano at UCLA). 'Rahul and England succeeded in creating a new ZIF material that made me, for the purpose of reporting the results, have to ask them to temporarily stop work.'

The inner part of ZIF may contain gas molecules. The active caps are like a chemical door that allows certain molecules - in this case carbon dioxide - to pass through and into the reservoir while simultaneously blocking larger molecules or feces. Other shaped death.

' We can scan and select a certain type of molecule that we want to keep, ' Phan said. ' The beauty of chemistry is that we are free to choose what kind of door we want and control what goes through that door .'

Yaghi said: ' Capturing carbon dioxide will produce cleaner energy. ZIF in a chimney will retain carbon dioxide in tiny holes before transferring it to storage . '

In ZIF 68, 29 and 70 materials, Banerjee and Phan emptied the holes, creating an open structure. The material then flows into the gas stream - for example, carbon dioxide (CO ₂ ) and carbon oxide (CO) along with a stream of carbon dioxide and nitrogen - only CO2 is retained. They are experimenting with other ZIF materials for many applications.

Carbon dioxide is damaging the lives of coral reefs and marine life. Yaghi stressed that the consequences of this gas would not be recoverable, at least for centuries to come.

Currently, the process of eliminating carbon dioxide emissions at generating stations involves the use of toxic materials and requires 20% to 30% of the station's energy, Yaghi said. In contrast, ZIF can remove carbon dioxide from gases and contain five times more than the porous carbon material currently described as works of art.

' With every liter of ZIF, you can hold up to 83 liters of carbon dioxide ' Banerjee explained.

The word ZIF, Yaghi emphasized, is used in the Bible to describe a land of magnificence and wonder. It also means graceful and radiant. ZIF is very suitable for this new material because the number of members is quite large and beautiful structure.

On the basic principle, the invention of ZIF also posed two major challenges for zeolite science. Zeolite is very strong, porous minerals made of aluminum, silicon and oxygen; They are used in refined gasoline, detergents and other products. Yaghi's collaborative group succeeded in replacing aluminum and silicon with metals such as zinc and cobalt, along with oxygen and imi groups to provide ZIF materials whose structure can be designed according to features.

Banerjee and Phan automated the synthesis process. Instead of mixing chemicals every time they make a reaction and making some reactions a day, they have made 200 reactions in less than an hour. The duo has implemented 9600 micro-reactions and from those reactions found 25 new structures.

Banerjee said: 'We continue to create new ZIF crystals every day. Those reactions produce crystals that look like diamonds'.

The co-author of the study is Bo Wang, a UCLA chemistry graduate who works at Yaghi's laboratory; Carolyn Knobler and Hiroyasu Furukawa of the intensive chemistry center of the California Institute of Nanotechnology at UCLA and Michael O'Keeffe of Arizona State University, chemistry and biochemistry.

In the early 1990s, Yaghi invented a new material called metal-organic structure (MOFs), described as a sponge crystal and also works to clean up energy. Yaghi can change the composition of MOF almost at will. Like ZIF, MOF has small holes - nano-sized entrances where Yaghi and colleagues can contain gases that are difficult to transport and store.

Yaghi's lab has created hundreds of MOF structures, with a variety of features and structures. Molecules can get into those structures without being hindered.