Coffee cup lids, the plastic film encasing paper towels, and the infinite number of single-use plastic shopping bags can be the source of energy and raw materials, if we only knew how to unlock their chemical bonds at a practical cost.

The U.S. Department of Energy’s Pacific Northwest National Laboratory (PNNL) has led an international team of researchers who seem to have cracked the problem.

To recycle and reuse plastics, they first have to be “cracked,” which involves splitting the strong bonds that keep them from breaking down in landfills. Cracking is done hot, requiring a lot of energy and driving up the process’s cost.

When the plastic molecules’ bonds break, the atoms and molecules immediately form other bonds that require other steps to fracture and eventually recover the materials in the form that’s needed.

The PNNL group has paired cracking with another reaction that uses catalysts to instantly convert plastic’s components to a liquid fuel similar to gasoline. The two reactions happen virtually simultaneously at 158°F, or about 70°C, which sharply cuts the amount of energy needed to spark the reactions.

The process works on numbers 4 and 5 plastics. Using PNNL’s process to break down #2 plastic, the HDPE (high-density polyethylene) used to make bottles for laundry detergent and other liquids, requires a pretreatment.

TRENDPOST: Making recycling plastic financially practical, and perhaps profitable, would be a major step toward solving the global plastics crisis.

The PNNL process has an advantage: it turns plastic into fuel. 

As we reported in “A Better Way to Make Bioplastics” (11 Oct 2022), scientists at the Texas A&M AgriLife Research Center and Washington University have devised a process to turn waste carbon dioxide—CO2—into biodegradable plastics.

Pairing the two breakthroughs hints at the possibility of a closed loop, in which waste plastics could be made into fuel, and carbon waste from fuel could be taken from factory waste streams or even the atmosphere and turned back into plastics.

Thanks to PNNL, tomorrow’s circular economy looks one step closer.

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