A group of American scientists from the ORNL managed to transform polyethylene, one of the most common plastics on the planet, into gasoline and diesel with a yield close to 60%, using a system based on molten salts with aluminum chloride.
What is remarkable is that this process is carried out at moderate temperatures, below 200 °C, which is an improvement over traditional methods like pyrolysis, which require up to 500 °C and consume more energy.
The reaction mechanism
The long polymer chains of polyethylene are fragmented into smaller molecules thanks to the catalytic action of the molten salts. At the molecular level, positively charged carbon ions are formed, triggering a cascade of reactions. Some end in light compounds similar to gasoline, while others result in heavier fractions comparable to diesel.
The interesting part is that it is not a chaotic decomposition, but a directed transformation, where chemistry allows the result to be oriented towards useful products. The use of advanced techniques such as spectroscopy and neutron scattering allowed for a precise understanding of the process, making it easier to consider its industrial scaling.
Advantages over traditional methods
This system eliminates the need for reaction initiators, avoids the use of noble metals or external hydrogen, and employs relatively cheap and abundant materials. Moreover, by operating under moderate conditions, it reduces energy consumption and simplifies operation.
All this makes it a more realistic model for scaling than other proposals that often remain limited to the laboratory due to their complexity or cost.
The salts used are hygroscopic, meaning they absorb moisture and can lose stability. The challenge now is to improve their confinement and facilitate their recovery for reuse in industrial cycles. Solving this point will be key to ensuring the viability of the process on a large scale.
Implications for the circular economy
This approach changes the narrative about plastic waste. It is not limited to reducing volume or avoiding landfills, but recovers energy value directly. In a context where plastic remains ubiquitous in packaging, textiles, and consumer products, technologies like this open the door to a more sophisticated circular economy, where carbon is reused instead of being lost.
Not all plastic has to become plastic again: in some cases, converting it into useful energy can be more efficient, especially when mechanical recycling is not viable.
Future prospects
In the short term, this technology could be applied in urban or industrial waste treatment plants, especially for fractions not recyclable by conventional methods. In the medium term, combined with renewable energies, it would allow the production of fuels with a lower carbon footprint, useful in sectors difficult to electrify such as heavy transport or industry.
It also opens up the possibility of decentralized models, with small installations near waste generation centers, reducing transportation and logistical costs. More efficiency, less impact.
The conversion of plastics into liquid fuels through molten salts represents a step towards a smarter waste management. Although it will not solve the plastic crisis on its own, it can play a key role if integrated into broader energy and recycling systems, providing practical and sustainable solutions for the future.
