Converting Plastic Waste and GHG Emissions into New, Usable Products

In an industry first, researchers from the University of Cambridge have successfully converted two waste streams—­plastic waste and greenhouse gas (GHG) emissions—into useful chemical products with a solar-powered reactor. This new system, detailed in a study recently published in Nature Synthesis, may pave the way to developing a solar-powered recycling plant in the future.

The researchers, led by professor Erwin Reisner, PhD, from the Yusuf Hamied department of chemistry, built a solar-powered reactor that converts both carbon dioxide derived from GHG and plastics into usable products. “Converting waste into something useful using solar energy is a major goal of our research,” Reisner said. “Plastic pollution is a huge problem worldwide, and often, many of the plastics we throw into recycling bins are incinerated or end up in a landfill.” In testing the reactor, the team successfully converted CO₂ into synthesis gas, which is a mixture of hydrogen and carbon monoxide used in formulating sustainable liquid fuels. The plastic was converted into glycolic acid, a key ingredient in many cosmetics products. Additionally, the reactor is not limited to these products; it can produce other products by changing the type of catalyst used. “What’s so special about this system,” said first co-author Subhajit Bhattacharjee, “is the versatility and tuneability—we’re making fairly simple carbon-based molecules right now, but in [the] future, we could be able to tune the system to make far more complex products just by changing the catalyst.”

The researchers were also encouraged to find that their reactor produced at much higher rates than conventional photocatalytic CO₂ reduction processes. “Generally, CO₂ conversion requires a lot of energy, but with our system, basically you just shine a light at it, and it starts converting harmful products into something useful and sustainable,” said co-author Motiar Rahaman, PhD. “Prior to this system, we didn’t have anything that could make high-value products selectively and efficiently.”

This technology may pave the way for many industries to lower their environmental footprint. “Developing a circular economy, where we make useful things from waste instead of throwing it into a landfill, is vital if we’re going to meaningfully address the climate crisis and protect the natural world. And powering these solutions using the Sun means that we’re doing it cleanly and sustainably,” Reisner said.