Crystal sponges excel at sopping up CO2

A new class of materials invented and developed by Omar Yaghi at the University of Michigan can store vast amounts of carbon dioxide. And one member of the class has the highest carbon dioxide capacity of any porous material, Yaghi and co-worker Andrew Millward report in a paper published online Dec. 1 in the Journal of the American Chemical Society.

The materials, called metal-organic frameworks (MOFs) and sometimes referred to as crystal sponges, previously have been shown to have great potential for storing hydrogen and methane. On the molecular level, MOFs are scaffolds made up of metal hubs linked together with struts of organic compounds, a structure designed to maximize surface area.

Just one gram of a MOF, in fact, has the surface area of a football field. By modifying the rods in various ways, Yaghi and his team have been able to increase the material's storage capacity, making it possible to stuff more gas molecules into a small area without resorting to high pressure or low temperature.

Yaghi compares the principle by which MOFs store CO₂ to placing a honeycomb in a room full of bees. "All the bees will come to the honeycomb, so you're able to contain a large number of bees in a small volume. What we've created is a material that acts like a honeycomb for adsorbing carbon dioxide."

The star performer in Yaghi's cast of MOFs is one dubbed MOF-177, which sops up 140 percent of its weight in CO₂ at room temperature and reasonable pressure (32 bar).

Put another way, "if you have a tank filled with MOFs, you can store in that tank as much carbon dioxide as would be stored in nine tanks that do not contain MOFs," Yaghi said. By comparison, a tank filled with porous carbon---one of the current state-of-the-art materials for capturing CO₂ in power plant flues---would hold only four tanks worth of CO₂.

MOFs can be made in large quantities from low-cost ingredients, such as zinc oxide---a common component of sunblock---and terephthalate, which is used in plastic soda bottles. And finding effective, low-cost ways of reducing CO₂ emissions is crucial, said Yaghi, who is the Robert W. Parry Collegiate Professor of Chemistry.

"Almost every region of the world is using more energy than ever before, and the prediction is that this will continue to increase, not just for petroleum, but also for coal and natural gas. Whenever you're burning fossil fuels, you're releasing CO₂ into the atmosphere, with devastating environmental effects that include melting the polar ice caps and changing the ocean's acidity. In the United States alone, each person is responsible for generating more than 15 tons of carbon dioxide a year, largely from automobile and power plant emissions," Yaghi said.

"I'm not exaggerating when I say that we are digging a big, black hole for ourselves by not addressing the problem of carbon dioxide emissions."

Source: University of Michigan

New materials can selectively capture carbon dioxide
UCLA chemists report a major advance in reducing heat-trapping carbon dioxide emissions in the Feb. 15 issue of the journal Science.
Mixed results: Combining scaffold ingredients yields surprising nanoporous structure
With a novel twist on existing techniques used to create porous crystals, University of Michigan researchers have developed a new, high-capacity material that may be useful in storing hydrogen, methane and carbon dioxide.
Chemists design world's lowest-density crystals for use in clean energy
Chemists at UCLA have designed new organic structures for the storage of voluminous amounts of gases for use in alternative energy technologies.
Towards hydrogen as fuel for cars and electronic devices
Chemists at UCLA and the University of Michigan report an advance toward the goal of cars that run on hydrogen rather than gasoline. While the U.S. Department of Energy estimates that practical hydrogen fuel will require concentrations of at least 6.5 percent, the chemists have achieved concentrations of 7.5 percent -- nearly three times as much as has been reported previously -- but at a very low temperature (77 degrees Kelvin).
New materials for better hydrogen traps
Using building blocks that make up ordinary plastics, but putting them together in a whole new way, University of Michigan researchers have created a class of lightweight, rigid polymers they predict will be useful for storing hydrogen fuel.
The work is described in today's (Nov. 17) issue of the journal Science.
More Solid than Solid: A Potential Hydrogen-Storage Compound
One of the key engineering challenges to building a clean, efficient, hydrogen-powered car is how to design the fuel tank. Storing enough raw hydrogen for a reasonable driving range would require either impractically high pressures for gaseous hydrogen or extremely low temperatures for liquid hydrogen. In a new paper researchers at the National Institute of Standards and Technology’s Center for Neutron Research have demonstrated that a novel class of materials could enable a practical hydrogen fuel tank.
Asian soot, smog may boost global warming in US
(AP) -- Smog, soot and other particles like the kind often seen hanging over Beijing add to global warming and may raise summer temperatures in the American heartland by three degrees in about 50 years, says a new federal science report released Thursday.
Scientists peel away the mystery behind gold's catalytic prowess
Few materials have exercised as much of a hold on the human imagination, or on human history, as has gold. But for all of its popular uses – money, medals, jewelry and more – gold's potential as a catalyst lay hidden until the 1980s, when Masatake Haruta and Graham Hutchings independently discovered that gold, which had long been considered inactive, could be an extraordinarily good catalyst. Haruta demonstrated the low-temperature oxidation of CO and Hutchings the hydrochlorination of acetylene to vinyl chloride.

Crystal sponges excel at sopping up CO2

Related stories:

News discussion: