Microwave PS recycling process honored

A Canadian company using microwaves to convert scrap polystyrene to styrene monomer has been awarded a Clean50 designation by a company promoting sustainability.

Pyrowave Inc. of Montreal garnered the award in the primary resources category for 2018. Clean50 awards were founded in 2011 by Delta Management Group, a Toronto-based sustainability and clean technology search firm.

Pyrowave has developed a new microwave technology better suited to PS-to-styrene production than earlier attempts at using microwaves to depolymerize PS, according to the company's co-founder Jocelyn Doucet. Other researchers in the field have encountered problems with electrical arcs generated when dirty resin is exposed to microwaves.

"We solved the problem with a power coupler," Doucet said in a phone interview. The power coupler prevents electric current jumping between surfaces of the scrap resin, he explained. Pyrowave has taken out patents and is applying for more patents in Canada, the United States and Europe. Doucet said the technology promises applications beyond plastic recycling.

Doucet said Pyrowave has encapsulated the microwave system into a 40-foot standard shipping container that is the prototype for parties that want to install the system. The prototype can process up to 330 pounds per hour of scrap PS with power consumption of 100 Kw per hour. He claimed styrene monomer yields of up to 85 percent.

He said the microwave approach doesn't need a catalyst like comparable pyrolysis methods to degrade PS to styrene. The catalysts in pyrolysis methods, typically heavy metal based, degrade with time and are messy to handle.

Doucet and his two partners started work on the microwave depolymerization route in 2010 through a research contract with the Polytechnique Montreal educational institution. The current technology is the third iteration of the development work.

Pyrowave has begun shipping styrene generated from the microwave system to major PS resin suppliers, some of which have expressed interest in the technology.

Doucet said his company is now seeking secure supplies of scrap PS from post-consumer and post-industrial waste streams.

Pyrowave has looked into depolymerization of other scrap plastics but is focusing now on PS. Early work has shown polyolefins can depolymerize to waxes and PET can yield terephthalic acid monomer.

The Clean50 awards are designed to identify and connect technology developers with the overall goal of helping in the fight against global warming.