NC West Virginia News

West Virginia University researchers are developing a new microwave technology to recycle polypropylene, one of the most widely used but least reusable plastics. Polypropylene is prevalent in various products, including car parts, food packaging, and textiles. Most of these items are single-use and contribute significantly to landfill waste.

A $1 million grant from the U.S. Department of Energy is backing WVU chemical engineer Yuxin Wang's initiative to use microwave technology to extract propylene from discarded polypropylene products. "We need to diversify our strategies for dealing with America’s abundant plastic waste," said Wang, an assistant professor at the WVU Benjamin M. Statler College of Engineering and Mineral Resources. He noted that only 1% of polypropylene is currently recovered, leaving 99% as waste.

Wang, alongside Srinivas Palanki, chair of the Department of Chemical and Biomedical Engineering, aims to find energy-efficient methods to convert polypropylene back into propylene for reuse in new products. "We make 150.3 million metric tons of propylene every year through energy-intensive processes like ethane steam cracking," Palanki explained. Recovering propylene from polypropylene could reduce energy consumption and emissions throughout the lifecycle of these plastics.

Previous efforts by other researchers have focused on thermochemical approaches such as pyrolysis, which have been largely unsuccessful with polypropylene. "The pyrolysis of polypropylene typically results in a propylene yield of less than 25% even with an optimized process," Wang stated. The challenge lies in using microwaves effectively and cost-competitively.

Microwave technology offers precise control over the process and allows recovery at lower temperatures compared to traditional methods — 300 degrees Celsius versus 600 or 700 degrees. In their approach, microwaves heat an intermediary catalyst material that then transfers heat to the polypropylene waste.

The goal is to "upcycle" polypropylene by breaking it down into its original chemical components for manufacturing various products. "In recycling, you crush a water bottle into small pieces and then use those pieces to build a bottle again," Wang said. Upcycling aims to generate chemicals that can be used beyond just making more polypropylene.

The project will also provide WVU students access to resources at the Advanced Photon Source facility at Argonne National Laboratory in Illinois. "APS has cutting-edge technology that we will use in this project," Wang added, highlighting the opportunity for collaboration between academic research programs and national labs.