Converting Plastic Into Fuel

Researchers at the University of Cambridge have made a groundbreaking advance in addressing two of today’s environmental issues: carbon dioxide emissions and plastic waste. They have developed a solar-powered method that transforms plastic bottles and carbon dioxide into sustainable fuels and useful chemicals, potentially paving the way for a circular economy. This innovation was detailed by chemistry professor Erwin Reisner and his team in a study published in the journal Nature Synthesis.

The challenge has been to convert these waste streams into valuable products simultaneously in an integrated process. While there have been efforts to develop catalysts for efficiently converting captured carbon dioxide into plastics and fuels, and separate initiatives to convert plastic waste into sustainable fuels using light-driven processes, the Cambridge team’s approach combines these processes in one solar-powered reactor.

This reactor features two compartments separated by a membrane, each with its own electrode. Carbon dioxide is converted into carbon-based fuels like carbon monoxide or formate using a negative electrode. On the other side, with the positive electrode, plastics from recycled sparkling water bottles are transformed into glycolic acid, a valuable chemical in the pharmaceutical and cosmetic industries. The process involves cleaning, chopping, freezing, and grinding the plastic bottles before they enter the reactor.

To harness sunlight to drive these reactions, the electrode dealing with carbon conversion is coated with a perovskite material, known for its efficiency in absorbing sunlight and converting it into electricity. The choice of catalysts is crucial; the team experimented with cobalt, a copper–indium alloy, and a biological enzyme to trigger the carbon dioxide conversion. Different catalysts resulted in different end products. For the conversion of plastics, a combination of copper and palladium is used at the anode.

The reactor operates with high efficiency, producing chemicals and fuels at rates significantly faster than traditional light- and catalyst-driven processes, without the need for external electricity. “Generally, [carbon dioxide] conversion requires a lot of energy, but with our system, you just shine a light at it, and it starts converting harmful products into something useful and sustainable,” explained co-author Motiar Rahaman in a press release.

As the researchers continue testing different catalysts, their goal is to refine the reactor’s capabilities to produce an even broader array of complex products. This innovative technology could offer an excellent sustainable solution to waste management.

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