chemists

Capturing hot carbon dioxide

December 13, 2024 By EarthWise Leave a Comment

Decarbonizing industries like steel and cement is a difficult challenge. Both involve emitting large amounts of carbon dioxide both from burning fossil fuels and from intrinsic chemical reactions taking place. A potential solution is to capture the carbon dioxide emissions and either use them or store them away. But this sort of carbon capture is not easy and can be quite expensive.

The most common method for capturing carbon dioxide emissions from industrial plants uses chemicals called liquid amines which absorb the gas. But the chemical reaction by which this occurs only works well at temperatures between 100 and 140 degrees Fahrenheit. Cement manufacturing and steelmaking plants produce exhaust that exceeds 400 degrees and other industrial processes produce exhaust as hot as 930 degrees.

Costly infrastructure is necessary to cool down these exhaust streams so that amine-based carbon capture technology can work.

Chemists at the University of California, Berkeley, have developed a porous material – a type of metal-organic framework – that can act like a sponge to capture CO2 at temperatures close to those of many industrial exhaust streams. The molecular metal hydride structures have demonstrated rapid, reversible, high-capacity capture of carbon dioxide that can be accomplished at high temperatures.

Removing carbon dioxide from industrial and power plant emissions is a key strategy for reducing greenhouse gases that are warming the Earth and altering the global climate. The captured CO2 can be used to produce value-added chemicals or can be stored underground or chemically-reacted into stable substances.

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Breakthrough in capturing ‘hot’ CO2 from industrial exhaust

Photo, posted March 3, 2010, courtesy of Eli Duke via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Capturing Carbon Dioxide With Plastic | Earth Wise

May 11, 2022 By EarthWise 2 Comments

The world is awash in both waste plastic and in carbon dioxide emissions. Researchers at Rice University have discovered a chemical technique for making waste plastic into an effective carbon dioxide absorbent for industry.

Chemists at Rice reported in the journal ACS Nano that heating plastic waste in the presence of potassium acetate produces particles with nanometer-scale pores that trap carbon dioxide molecules. According to the researchers, these particles could be used to remove CO2 from the flue gas streams of power plants.

Significant sources of CO2 emissions like power plant exhaust stacks could be fitted with this waste-plastic-derived material to absorb large amounts of carbon dioxide that would otherwise enter the atmosphere.

The Rice University process is an enhancement to the current process of pyrolyzing waste plastic – that is, breaking it down in the presence of heat. By pyrolyzing plastic in the presence of potassium acetate, porous particles are formed that can hold up to 18% of their own weight in carbon dioxide.

According to the researchers, the cost of capturing carbon from a power plant would be $21 a ton, which is far less expensive than existing energy-intensive processes used to pull carbon dioxide from natural gas feeds.

The sorbent material can be reused. Heating it to about 167 degrees Fahrenheit releases trapped carbon dioxide from the pores and regenerates about 90% of the material’s binding sites.

The Rice process may represent a much better way to capture carbon dioxide from power plant exhaust stacks. It could be a way to make use of one environmental problem – waste plastic – to deal with another one.

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Treated plastic waste good at grabbing carbon dioxide

Photo, posted April 19, 2021, courtesy of Ivan Radic via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Recycling Tough Plastics | Earth Wise

September 3, 2020 By EarthWise Leave a Comment

Thermoset plastics are ones that contain polymers that cross-link together during the curing process to form an irreversible chemical bond. This improves the material’s mechanical properties, provides chemical resistance, heat resistance, and structural integrity. Thermosets include epoxies, polyurethanes, and rubber used for tires. The big problem with thermosets is that they cannot be easily recycled or broken down after use.

Seventy-five percent of all plastics are thermoplastics, which can be recycled by heating them until they become liquid and can then be remolded. Thermoset plastics, on the other hand, have such strong chemical bonds that they simply will not melt. They will typically burn before they can be remolded.

Chemists at MIT have recently developed a way to modify thermoset plastics with a chemical linker that makes them much easier to break down, but still retain the mechanical properties that make them so useful.

In a study published in Nature, the researchers produced a degradable version of a thermoset plastic called pDCPD. They then broke the plastic down into a powder and were able to use the powder to create more pDCPD. The paper also proposed a theoretical model that suggests that their approach could be used for a wide range of other plastics and polymers, including rubber.

By adding a chemical called a silyl ether monomer to the liquid precursors that from pDCPD plastic, they found that the resultant material retained its mechanical strength but can be broken down into a soluble powder upon exposure to fluoride ions.

Using this approach with other thermoset materials, the researchers believe it will be possible to create recyclable versions of many of the toughest plastic materials.

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Chemists make tough plastics recyclable

Photo, posted September 1, 2019, courtesy of Luke McKernan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.