Production of Diesel-like Oil from Co-Pyrolysis between Used Lubricant Oil and Plastic Wastes

Abstract

Pyrolysis is the most effective method to recover hydrocarbon materials from plastic wastes. This study improved the pyrolysis process of solid plastic wastes. The copyrolysis process of used lubricant oils and mixed plastic wastes was developed. The optimization of co-pyrolysis conditions was studied to produce diesel-like oil product. Plastic wastes included high-density polyethylene (HDPE), polypropylene (PP), and polystyrene (PS). The best proportions of raw materials in a laboratory scale were at atmospheric pressure at a final temperature of 450 degree Celsius with and without a catalyst. The investigated ratios between used lubricant oil (Oil) and plastic waste (Oil:HDPE:PP:PS) were 50:30:20:0, 50:30:0:20, 50:0:30:20, and 50:30:10:10 by weight. Kinetic of co-pyrolysis studied was Oil:HDPE, Oil:PP, and Oil:PS at heating rates of 5 degree Celsius /min, 10 degree Celsius/min, and 20 degree Celsius /min. The appropriate proportion of raw materials was selected for co-pyrolysis prototype (10 kg/day). It was found that oil produced from Oil:HDPE:PP:PS at the weight ratio of 50:30:20:0 gave standard diesel oil as specified by the Ministry of Energy (Thailand), except its lower standard of flash point. This proportion was tested with the co-pyrolysis prototype by studying oil property of three reactor temperature ranges (less than 400 degree Celsius, 400–425 degree Celsius, and 425–450 degree Celsius). The analysis of oil produced at 400–425 degree Celsius exhibited diesel-like fuel property. The parameters and activation energy data from the kinetic study of co-pyrolysis were used to design heat capacity of co-pyrolysis reaction. The co-pyrolysis prototype can be used to produce diesel-like fuel.