Capturing CO2 with waste plastic

According to Rice University scientists, heating plastic waste in the presence of potassium acetate can produce particles with nanometer-scale pores that trap carbon dioxide molecules. This newly discovered chemical technique could to turn waste plastic into an effective CO2 sorbent for industry. Recently, their findings were reported in the American Chemical Society journal ACS Nano.

A current process to pyrolyze plastic known as chemical recycling produces oils, gases and waxes, but the carbon byproduct is nearly useless, he said. However, pyrolyzing plastic in the presence of potassium acetate produces porous particles able to hold up to 18 % of their own weight in CO2 at room temperature.

To make the material, waste plastic is turned into powder, mixed with potassium acetate and heated at 600 °C for 45 minutes. This creates pores, most of which are approximately 0.7 nanometers in size.  Higher temperatures led to wider pores.

The lab estimates the cost of carbon dioxide capture from a point source like post-combustion flue gas would be $21 a ton, far less expensive than the energy-intensive, amine-based process in common use to pull carbon dioxide from natural gas feeds, which costs $80-$160 a ton.

The research was published on April 5 in ACS Nano, titled ’Plastic Waste Product Captures Carbon Dioxide in Nanometer Pores’ (James Tour, Wala Algozeeb, Paul Savas, Zhe Yuan).

Pores in this micron-scale particle, the result of pyrolyzing in the presence of potassium acetate, are able to sequester carbon dioxide from streams of flue gas (Credits: Rice University)

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