In a first, a solar-powered reactor converted plastic and greenhouse gases into sustainable fuels

Under normal temperature and pressure conditions, the reactor could efficiently convert plastic bottles and CO2 into CO, syngas, and glycolic acid.
Deena Theresa
Representational picture of a reactor producing sustainable fuels.
Representational picture of a reactor producing sustainable fuels.

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Researchers from the University of Cambridge developed a first-of-its-kind system that can simultaneously convert plastic waste and greenhouse gases into two chemical products by drawing energy from the sun.

In a solar-powered reactor, carbon dioxide (CO2) and plastics are converted into sustainable fuels and valuable products used in various industries.

The results are reported in the journal Nature Synthesis.

"Converting waste into something useful using solar energy is a major goal of our research," Professor Erwin Reisner from the Yusuf Hamied Department of Chemistry, the paper’s senior author, said in a statement. "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."

In a first, a solar-powered reactor converted plastic and greenhouse gases into sustainable fuels
The test reactor.

A significant step in the transition to a more sustainable, circular economy

The system converted CO2 into syngas, a building block for sustainable liquid fuels, and plastic bottles were converted into glycolic acid, a regular in the cosmetics industry. Also, it can produce different products depending on the type of catalyst in the reactor.

"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.

"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," said Bhattacharjee.

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In a first, a solar-powered reactor converted plastic and greenhouse gases into sustainable fuels
A graphical illustration of the process.

A system that can efficiently make high-value products from waste

The integrated reactor has two separate chambers, one for plastic and the other for greenhouse gases. The reactor also contains a light absorber based on perovskite.

Different catalysts were designed, which were then integrated into the light absorber. When tests were conducted under normal temperature and pressure conditions, it was revealed that the reactor could efficiently convert PET plastic bottles and CO2 into different carbon-based fuels such as CO, syngas, or formate, in addition to glycolic acid. 

The release also stressed that the reactor produced the products at a higher rate 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 Rahaman. "Prior to this system, we didn’t have anything that could make high-value products selectively and efficiently."

In the next five years, the system could perhaps power a recycling plant

Reisner recently received new funding from the European Research Council to help the development of their solar-powered reactor. 

The researchers hope to develop the reactor further to produce more complex molecules. Someday, it could be used to develop a solar-powered recycling plant. 

 

Study Abstract:

Solar-driven conversion of CO2 and plastics into value-added products provides a potential sustainable route towards a circular economy, but their simultaneous conversion in an integrated process is challenging. Here we introduce a versatile photoelectrochemical platform for CO2 conversion that is coupled to the reforming of plastic. The perovskite-based photocathode enables the integration of different CO2-reduction catalysts such as a molecular cobalt porphyrin, a Cu91In9 alloy and formate dehydrogenase enzyme, which produce CO, syngas and formate, respectively. The Cu27Pd73 alloy anode selectively reforms polyethylene terephthalate plastics into glycolate in alkaline solution. The overall single-light-absorber photoelectrochemical system operates with the help of an internal chemical bias and under zero applied voltage. The system performs similarly to bias-free, dual-light absorber tandems and shows about 10‒100-fold higher production rates than those of photocatalytic suspension processes. This finding demonstrates efficient photoelectrochemical CO2-to-fuel production coupled to plastic-to-chemical conversion as a promising and sustainable technology powered by sunlight.

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