Carbon capture breakthrough: asphalt

January 8, 2015 | By Barbara Vergetis Lundin

Rice University scientists have made an amazing discovery that could change the face of carbon capture.

Powder drawn from asphalt has the ability to capture more than its own weight in carbon dioxide under pressure. Credit: Jeff Fitlow/Rice University

Last year, Rice scientists announced that they had discovered a "green" carbon capture material for wellhead sequestration and predicted that an even better compound was on the horizon -- one that could be cheaply and easily made from asphalt of all things.

The scientists have come up with several versions, the best of which is a powder that holds 114 percent of its weight in carbon dioxide. These new porous carbon materials capture carbon dioxide molecules at room temperature while letting the desired methane natural gas flow through just like the "green" material.

The basic compound, asphalt-porous carbon (A-PC), captures carbon dioxide as it leaves a wellhead under pressure supplied by the rising gas (about 30 atmospheres, or 30 times atmospheric pressure at sea level). When the pressure is relieved, A-PC spontaneously releases the carbon dioxide, which can be piped off to storage, pumped back downhole or repurposed for such uses as enhanced oil recovery.

"This provides an ultra-inexpensive route to a high-value material for the capture of carbon dioxide from natural gas streams," Rice laboratory chemist James Tour said. "Not only did we increase its capacity, we lowered the price substantially."

A-PC is created by mixing asphalt with potassium hydroxide at high temperatures. The lab continues to tweak the material but Tour says it's already better for carbon capture than other materials in current use. He explained that Amine-based materials currently used by power plants to absorb carbon dioxide are expensive and corrosive, and can only capture about 13 percent carbon dioxide by weight.

Further, materials in development based on metal organic frameworks are far more expensive to produce and don't show as great a selectivity for carbon dioxide over methane, he said.

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http://www.fierceenergy.com/story/carbon-capture-breakthrough-power-plants-asphalt/2015-01-08