Experimental investigation to identify the type of waste plastic pyrolysis oil suitable for conversion to diesel engine fuel

Abstract

Plastics for various applications is increasing every year due to outstanding advantages, but after use recycling and disposal have remained a challenge. In this paper, through experiments, we compare properties of pyrolysis oil derived from after use HDPE (High-density polyethylene), LDPE (Low-density polyethylene), PP (Polypropylene)and styrene for their suitability as diesel engine fuel. This experimental study is to identify which type of plastic is suitable for blending with diesel. The physicochemical properties of pyrolysis oil of HDPE, LDPE, PP, and styrene were tested, tabulated and compared with diesel. The physicochemical properties of polypropylene pyrolysis oil (PPO) were found to be superior to the produced pyrolysis oil of HDPE, LDPE, and styrene. The GC-MS(Gas chromatography-mass spectrometry)and FT-IR (Fourier transform-infrared spectroscopy) were taken for pyrolysis oil of HDPE, LDPE, PP, and styrene and compared with diesel. PPO showed lower carbon number chain compounds compared to the other three waste plastics. We selected PPO for diesel engine performance and emission trials based on the results of the above tests. PPO was blended in the ratios of 5%, 10% and 15% with diesel. Combustion analysis showed a increase in cylinder pressure in comparison to diesel values. The heat release rates (HRR) were sharply higher than diesel. Both cylinder pressure and HRRvalues for PPO increased as the blend ratios increased. The emission results showed an increase in carbon monoxide (CO), hydrocarbon (HC)and oxides of Nitrogen (NO x )emissions. The multiple times increase in emissions is due to the presence of unsaturated hydrocarbons and higher carbon number of saturated compounds in PPO. GC-MS tests confirmed the presence of such compounds in PPO. To reduce the unsaturation to negligible levels, we will take up future experiments in hydrogenating PPO with various catalysts and test the performance and emissions in diesel engines. The experiment and analysis plan for conversion of solid waste plastics to diesel fuel. • Four types of plastics selected to determine which plastic has a diesel like quality. • Physicochemical properties, FTIR, GCMS results showed Polypropylene had diesel like qualities. • Diesel Engine trials done with polypropylene pyrolysis oil blended with diesel as fuel. • Engine trial results showed delayed combustion, high heat release rate and higher emission.