Researchers found a way to transform plastic waste and greenhouse gases into sustainable fuels and other high-value products using just energy from the sun, according to a study published in the journal Nature Synthesis.
This novel process, developed by a team from the University of Cambridge, UK, can convert two waste streams into one chemical product. In addition, the reaction can be completed in a solar-powered reactor.
The reactor converts carbon dioxide (CO2) and plastics into a series of products used in different industries. For example, the authors managed to convert CO2 into syngas, which is used to produce sustainable liquid fuels; and plastic bottles into glycolic acid, which is used in the cosmetics industry. What’s more, the system can be tuned to produce different products by using different catalysts in the reactor.
For the authors, converting plastics and greenhouse gases to useful and valuable products using solar energy is an important step towards sustainability. “Converting waste into something useful using solar energy is a major goal of our research,” said Professor Erwin Reisner from the Yusuf Hamied Department of Chemistry, the paper’s senior author. “Plastic pollution is a huge problem worldwide, and often, many of the plastics we throw into recycling bins are incinerated or end up in landfill.”
Other solar-powered technologies that use plastics or greenhouse gases show promising results, but this is the first time both processes have been combined in a single reaction.
“A solar-driven technology that could help to address plastic pollution and greenhouse gases at the same time could be a game-changer in the development of a circular economy,” said Subhajit Bhattacharjee, the paper’s co-first author. “We also need something that’s tuneable so that you can easily make changes depending on the final product you want,” added co-first author Dr. Motiar Rahaman.
The system works with an integrated reactor with two separate compartments: one for plastics and one for greenhouse gases. The reactor then uses a perovskite light absorber and different catalysts to promote the reaction. Tests under normal temperature and pressure showed that the system could be used to convert PET bottles and CO2 into different fuels, such as syngas, formate, and glycolic acid.
“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 Rahaman. “Prior to this system, we didn’t have anything that could make high-value products selectively and efficiently.”
“What’s so special about this system is the versatility and tuneability – we’re making fairly simple carbon-based molecules right now, but in future, we could be able to tune the system to make far more complex products just by changing the catalyst,” added Bhattacharjee.
Over the next few years, the team hopes to develop ways to produce more complex molecules. It’s possible that this technology could be used in the future to create an entirely solar-powered recycling plant. “Developing a circular economy, where we make useful things from waste instead of throwing it into landfill, is vital if we’re going to meaningfully address the climate crisis and protect the natural world,” said Reisner. “And powering these solutions using the Sun means that we’re doing it cleanly and sustainably.”
Bhattacharjee, S., Rahaman, M., Andrei, V. et al. Photoelectrochemical CO2-to-fuel conversion with simultaneous plastic reforming. Nat. Synth (2023). https://doi.org/10.1038/s44160-022-00196-0