The plastic problem remains a global concern, with more than 400 million tons produced annually and a large portion quickly becoming waste. The circular economy of plastic still seems like a distant dream due to low recycling rates and the predominance of landfills and incineration.
Innovation in the United States: Aluminum, plastics, and fuels
A team from the United States Department of Energy at the Oak Ridge National Laboratory (ORNL) has developed an innovative method to convert polyethylene, the plastic commonly used in bags and packaging, into liquid fuels like gasoline and diesel.
This process uses molten salts with aluminum chloride and operates at temperatures below 200 ºC, contrasting with the 450 to 500 ºC required in conventional pyrolysis. This not only reduces energy consumption but also allows for greater control over the final products.
In an article published by the Journal of the American Chemical Society, the ORNL team has applied for a patent for their method. Liqi Qiu, one of the researchers, highlighted the efficiency of the process that selectively converts polyethylene into gasoline.
The technique dispenses with noble metal catalysts, organic solvents, and external hydrogen, an approach described by Zhenzhen Yang as a significant advantage. The scientists followed the process using advanced techniques to understand how polymer chains break down into gasoline-like and diesel-like fractions.
The method’s yield is remarkable, reaching 60% in gasoline-type fractions under mild conditions. The conversion produces a mixture of branched alkanes in the C6 to C12 range, aligning with current market needs.
However, although the process promises to reduce oil dependency, burning these plastic fuels still releases CO2 into the atmosphere. The EPA indicates that a gallon of gasoline emits 8,887 grams of CO2, while a gallon of diesel produces 10,180 grams.
The environmental benefit could lie in reducing oil demand and better managing plastic waste that would otherwise end up in landfills or incineration. Still, a complete life cycle analysis is essential to understand the total impact.
Additionally, the process faces practical challenges, such as the absorption of water by aluminum salts, which could complicate its industrial scaling. Also, handling mixed waste can affect the process’s efficiency.
In summary, although this advancement does not mean we will soon be using plastic bags as fuel, it demonstrates that it is possible to convert some difficult types of plastics into useful products with less energy than expected. However, for a sustainable future, reducing, reusing, and mechanically recycling will remain essential.
