Environmental impact of waste plastic oil and hydrogen-enriched diesel engines: A comprehensive review on performance, combustion, and emissions.

This review examines the sustainable conversion of waste plastic into waste plastic oil (WPO) via catalytic pyrolysis, focusing on its potential as an alternative fuel for diesel engines. WPO, primarily derived from polyethylene terephthalate (PET) and other common plastics, exhibits fuel properties comparable to petroleum diesel but presents challenges such as longer ignition delay and increased emissions when used alone. Blending WPO with diesel and enriching these blends with hydrogen has been shown to improve combustion efficiency, reduce brake specific fuel consumption (BSFC), and lower emissions of carbon monoxide (CO), hydrocarbons (HC), and smoke, although nitrogen oxides (NOx) emissions tend to increase. The review highlights the importance of catalyst selection and reactor design in optimizing pyrolysis and calls for further research on hydrogen-enriched WPO blends, antioxidant additives, and emission control strategies to enhance the sustainability and performance of WPO as a long-term alternative fuel.