Many of us are careful to put our plastic trash into the appropriate recycling bins hoping that we are helping to stem the global tide of plastic waste. But many plastics are not recyclable at all and recycling those that are is not even always a good thing. Breaking down plastics can generate polluting microplastics that are themselves a major environmental problem. And perhaps the biggest problem for recycling efforts is that they are not cost effective and generally incur huge losses.
Chemical engineers at the University of Wisconsin-Madison recently published a study in the journal Nature outlining a new technique for turning low-value waste plastic into high-value industrial chemicals.
The technique makes use of two existing chemical processing techniques. The first is pyrolysis, which is high-temperature heating in an oxygen-free environment. Heating waste plastic in this way produces pyrolysis oil, a liquid mix of various compounds that includes large amounts of olefins. Olefins are simple hydrocarbons that are a central building block of many chemicals and polymers. Olefins are most often produced by energy-intensive processes like steam cracking of petroleum.
The UW-Madison process takes the olefins and subjects them to a process called homogenous hydroformylation catalysis, which converts them into aldehydes, which can then be further reduced into important industrial chemicals.
The payoff is that the process can take waste plastics, which are only worth about $100 a ton, and turn them into high-value chemicals worth $1,200-$6,000 a ton. If the process can be optimized and otherwise made ready for industrial-scale use, it would be a real game-changer in the battle against plastic waste.
Photo, posted September 16, 2015, courtesy of Oregon State University via Flickr.