Left to right: Liangbing Hu (Electrical & Computer Engineering and Materials Science) and Shu Hu (Chemical & Environmental Engineering). Credit: Qian Zhang
Yale University researchers have developed a novel technique which efficiently converts plastic waste into fuels or other valuable products. The pyrolysis-based technique molecularly breaks down the plastics resulting in components used to produce fuel and other products.
The method, published in the journal Nature Chemical Engineering, avoids the costly catalysts used in traditional methods while also resolving challenges such as low conversion rates that are commonly found in catalyst free operations. The resulting pyrolysis method is highly selective, energy efficient, and catalyst free.
Key to the success is a 3D-printed electrically heated carbon column reactor which contains three sections of decreasing pore sizes, ranging from one-millimeter to 200-nanometer pores. As chemicals pass through, these hierarchical pours control the reaction progress while providing an efficient means of controlling reactor temperatures.
During testing the team achieved a record high yield of nearly 66% when converting polyethylene, a commonly found plastic, into chemicals which can be used for fuels.
While 3D printing the reactor allowed for precise control of pore size and pyrolysis effects, the team also used a device made of commercially available carbon felt to demonstrate a more scalable approach. Even without the optimization of 3D printing, the design still improved pyrolysis product selectivity resulting in a satisfactory 56% conversion.
"These results are very promising and show a great potential for putting this system into real-world application and offering a practical strategy for converting plastic waste into valuable materials," said Shu Hu, assistant professor of chemical & environmental engineering.