Plastic pyrolysis is a method to convert waste plastics into a range of useful products like hydrocarbon liquids like fuel oil, gases like methane and hydrogen and wax. This helps in not only reducing the plastic waste but also in generating some useful energy products from the process. The focus of the project is on the pyrolysis of waste polyethene terephthalate (PET), a type of plastic from which all the water and soft drinks bottles and many fabrics are made. The aim of this project is to maximise the yield of benzene in the liquid oil obtained on pyrolysis of PET. The catalyst used in the process is calcium oxide (CaO), which is synthesized from waste eggshells that contain calcium carbonate (CaCO3). The process parameters (reaction temperature, catalyst loading etc.) would be optimized to obtain high yields of benzene, which is a useful chemical intermediate. The residue obtained after the pyrolysis process is calcium carbonate (CaCO3), which can be calcined (heated at 9000 C to convert it again to CaO) and used as a catalyst in the next experiment. Thus, the catalyst can be reused after each experiment.
This is a new idea and hasn't been reported in the literature.
The work is still in a preliminary stage and we are now trying to increase the liquid yield.
How efficient your process is as compared to other processes?
Till now, we have checked the reusability of the catalyst (Calcium oxide) by observing the changes in oil composition obtained after pyrolysis of waste PET. We are observing consistency in oil yields till 5th run. Most PET recycling technologies either convert PET back to polyester yarn or flakes unlike ours.