Environment

Chemical conversion process gives plastic waste new life as fuel

Chemical conversion process gi...
Chemical engineer Linda Wang led a research team at Purdue University in coming up with a new way to convert a common plastic into oil, opening up some exciting possibilities
Chemical engineer Linda Wang led a research team at Purdue University in coming up with a new way to convert a common plastic into oil, opening up some exciting possibilities
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Chemical engineer Linda Wang led a research team at Purdue University in coming up with a new way to convert a common plastic into oil, opening up some exciting possibilities
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Chemical engineer Linda Wang led a research team at Purdue University in coming up with a new way to convert a common plastic into oil, opening up some exciting possibilities

Millions of metric tons of plastic are produced each year and in reality, very little of it is recycled. But what if there were more ways of turning this waste into something valuable, such as new plastics or different types of fuel? Scientists at Purdue University have taken a promising step towards this goal with a new technology that can turn the majority of a commonly used plastic into the building blocks for all kinds of materials, something they hope can inspire new solutions for our plastic pollution problem.

Estimates vary on how much plastic winds up in landfill, how much ends up being recycled and how much washes into the ocean, but there's no question plastic waste is a big problem. As an indication, a 2015 paper estimated that somewhere between 5 and 12.7 million metric tons of plastic waste winds up in the ocean each year, and what happens to it from there is a great unknown.

The solution to this problem is far more complex than finding new ways of recycling the ubiquitous material, but it is certainly a step in the right direction. Elsewhere, we have seen promising experimental technologies that can convert plastic bags into high-value carbon nanotubes, turn ocean plastics into usable diesel fuels and turn plastic bottles into other fuels and waxes.

The work at Purdue University focuses on a type of plastic called polyolefin, the most common type of thermoplastic that features in everything from bottle caps to scientific instruments.

"Our strategy is to create a driving force for recycling by converting polyolefin waste into a wide range of valuable products, including polymers, naphtha (a mixture of hydrocarbons), or clean fuels," says Linda Wang, chemistry professor at Purdue University and leader of the research team. "Our conversion technology has the potential to boost the profits of the recycling industry and shrink the world's plastic waste stock."

In pursuing this strategy, Wang and her team turned to a technique called hydrothermal liquefaction, a process of heating materials up to moderate temperatures under high pressure to convert them into oil. In this case, the team was able to transform 91 percent of the polyolefin into oil consisting of paraffins, cyclics, aromatics and olefins, unsaturated hydrocarbons that serve as the foundation for polyolefins.

And that opens up a range of possibilities, according to the scientists. This oil and its ingredients can then be turned into gasoline blendstocks and feedstocks for other chemicals. They can also be separated into specialty solvents or fuels such as gasoline or diesel. So much so, the team estimates that the fuels generated from discarded polyolefin could meet around four percent of the globe's demand for gasoline and diesel fuels each year.

To that end, the researchers have now teamed up with Purdue University's Fuel Laboratory of Renewable Energy to try and optimize the conversion process. They are also looking for partners to help demonstrate the technology's potential on a commercial scale.

You can hear more from Wang in the video below, while the research was published in the journal ACS Sustainable Chemistry and Engineering.

Source: Purdue University

Chemical Conversion of Plastic Waste into Fuel

7 comments
owlbeyou
For a number of years, ever since I learned that plastic polymer types have to be sorted separately and cannot be mixed, I've been asking myself why difficult-to-identify plastics (petroleum products) aren't re-processed back into fuel. Surely we could have solved this problem years ago?
The Bishop of D
"One man gathers what another man spills." -- St. Stephen by the Grateful Dead
Captain Danger
Just burn the garbage and turn it int o electrical power. The technology has existed for some time to scrub the exhaust air. We would not have to deal withe PIA of sorting garbage, no complaining about landfills and if it was done in Asia no dumping of garbage into the ocean.
Leonard Foster Jr
Wait turn plastic back into fossil fuels so we can heat up the planet even more??
Aloysius
This is good. Plastic will be the death of us all.
ljaques
Excellent, go for it! One problem: Our recycling center does not require us to separate plastics and they do not take bottle caps/lids/plastic film, etc. In their newest brochure, I found out that they do no not take half my cardboard waste, either. Some day, greenies will get it together. Until then, we all do what we can.
Nik
Logically, if plastic is made from oil, it can be converted back to oil, without the necessity of sorting. If there was a financial reward for its return, then more, much more, would be returned. I can remember, as a kid, in the 50's, collecting all sorts of waste, paper, cardboard, bottles etc, and carting to the 'salvage centre' to boost my pocket money. Maybe today's kids are given too much pocket money to be interested. If there was also a penalty for not returning it, that would also help, even if it just tended to make people less inclined to accept it in the first place. Many years ago, I obtained a sample of a board, made from mixed recycled plastic, that had been shredded, compressed, and heated to cause it to bond together, and then covered with a thin film both sides. It was promoted as an agricultural board for lining animal enclosures, but it never seemed to have reached production. It seems to me that the recycling options for plastics need an injection of imagination to find new uses for raw waste, rather than, as now, nice clean waste only, that can be recycled into the same products. As CO2, = heating the planet, is a myth, then using the masses of waste plastic in power stations to generate electricity to power all the proposed ev's would be a simple solution. Possibly old coal stations could be converted, and fitted with updated exhaust cleaning systems. Coal stations were terribly inefficient, as some used more energy to pulverise the coal, for fluidised injection, than they put into the grid. Waste plastic may be less greedy of energy.