HONG KONG — Can a professor working out of a modest laboratory in a teachers' college crack one of the biggest technical challenges facing plastics recyclers?
Hong Kong Institute of Education chemistry professor Stephen Chow hopes so.
Chow's research was spurred by a growing problem — what to do with the 6 million metric tons of solid waste Hong Kong's 7 million people generate each year, according to city statistics.
Hong Kong residents haven't caught the frugal bug like other Asian powerhouses — per capita domestic waste in 2011 was a hefty 1.36 kilograms every day, compared to 0.95 kilograms in Seoul and 0.77 kilograms in Tokyo, according to the city's Environment Bureau.
At current rates, the city's three landfills in the semirural New Territories are expected to be full by the end of the decade.
And since Hong Kong comprises a dinky 1,014 square kilometers — an area smaller than New York City — land is at a premium.
Chow's research focuses on “cracking,” or breaking down, polyethylene, polypropylene, PVC and polystyrene.
“We can reduce PS, PVC, PE and PP back to organic fuel,” he said.
Cracking polymers requires a combination of heat and pressure — pyrolysis, and sometimes, a catalyst. The problem is generating those high temperatures and pressure — always a challenge in a cost-sensitive industry like recycling.
“This is a really big challenge for me. How can I make a catalyst have an interaction with an inert polymer,” Chow said.
Chow claims to be working on a catalyst that takes a scant 10 minutes to crack the polymer. The catalyst works at low pressure and temperature, resulting in energy cost savings of up to 95 percent.
“My catalyst is cleaner and faster,” says Chow, who did post-doctoral research under Nobel Chemistry Prize winner Jean Marie Lehn at the University of Strasbourg.
Completely cracking the complex chains and rings that make up plastics can take from 20 minutes to an hour. Doing this eliminates the need to bury the scrap in a landfill but generates carbon dioxide, a greenhouse gas.
Chow declined to go into details while he has patent applications pending in Hong Kong, the European Union, the United States and China. And while he's written dozens of scientific articles, he hasn't yet published the results of his latest research.
Still, he was happy to show a Plastics News reporter around his lab, staffed by graduate assistants.
Chow's experiments to date are confined to kilogram-sized samples of genuine post-consumer packaging — for example, ground-up bottles of body spray and dish detergent.
His research is definitely a work in progress.
“I'm still working on fundamental scientific questions. For example, can I control the catalytic reaction in order to control the length of the hydrocarbon?” Chow says.
On the output side, he's still unsure whether his method for cracking PVC — a complex molecular chain studded with hydrogen and chlorine atoms — creates highly toxic chlorine gas or hydrochloric acid. And he's testing the emissions for nitrous oxide, sulfuric dioxide and carcenogenic particulate matter.
He readily acknowledged that work hasn't begun on the hard part of scaling up his technique to handle the 1,100 metric tons of plastics Hong Kong throws away every day.