Chemicals can be used to turn plastic waste into useful products. The scientists said that a new study may improve the ability of one method to process hard-to-recycle mixed plastic.
Pyrolysis involves heating plastic in an oxygen-free environment, causing the materials to break down and create new fuels. The scientists said that current commercial applications can only handle certain types of plastic.
Hilal is an assistant professor of energy engineering and chemical engineering at Penn State. While we are trying to develop technologies that can recycle real waste, we need to understand the interaction effects between different polymers.
The scientists used different catalysts to study the interaction effects between the two types of plastic. They found a catalyst that could be used to convert mixed LDPE andPET waste into liquid fuels. The process of inducing the plastic to break down is aided by the addition of catalysts.
The Virginia S. and Philip L. Walker Jr. Faculty Fellow in the John and Willie Leone Family Department of Energy and Mineral Engineering said that this type of work can allow them to give guidelines to industry. Before scaling up, it's important to discover what kind of synergies exist between these materials during advanced recycling and what types of applications they might be right for.
The plastic used in food packaging is engineered to keep the product fresh and safe, but it is difficult to recycle because the layers have to be separated.
If you want to recycle them, you need to separate the layers and use the single streams. It's a very important option because of the way it can be handled. It's difficult to find a technique that accepts the complexity of the plastic materials.
The scientists said that the first step to developing new commercial pyrolysis processes is to have a better mechanistic understanding of how dynamic plastic waste mixes break down.
During tests with each of the three catalysts they used, the scientists observed interaction effects between LDPE and PET after they separated them. Scientists reported the findings in a journal.
There are products that could be good candidates for gasoline.
The team was able to model the interaction effects on LDPE and PET with each of the catalysts. Predicting the behavior of a system is important for understanding why reactions are happening.
Experiments under well-defined and well-controlled conditions are the focus of the research group.
Studies on understanding reaction pathways and developing models are the first steps to process improvement. If we don't have our models right, the results won't be accurate.
She hoped the research would lead to better environmental responsibility in the recovery, processing and utilization of Earth resources.
According to a global analysis of all mass-produced plastics, a total of 8.3 billion metric tons of new plastic is expected to be generated worldwide to date. Almost all of the plastic waste contains hazardous chemicals and has been left to accumulate in landfills or natural environments.
"Doing nothing is worse than whatever we do," he said. If we don't include those plastic into the economy again, they will end up in landfills or in the ocean. It's better to find a value than nothing. We treat plastic as waste because it's valuable.
Sean Timothy Okonsky is a PhD student in the Department of Chemical Engineering at Penn State.
More information: Sean Timothy Okonsky et al, Catalytic co-pyrolysis of LDPE and PET with HZSM-5, H-beta, and HY: experiments and kinetic modelling, Reaction Chemistry & Engineering (2022). DOI: 10.1039/D2RE00144F
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