High Quality Fuel with Less Pollution from Plastic Waste

Last Updated on May 7, 2018 by Bharat Saini

Plastic Derived Oil (PDO), having characteristics similar to Diesel, has been derived on successfully converting Packaging Plastic Waste by Pankaj Tiwari and Pallab Das Researchers from IIT Guwahati, Department of Chemical Engineering. They hope to create ideal operating conditions to provide high-quality oil with less pollution that could soon help fuel cars. Researchers collected plastic waste from houses, cleaned and segregated them according to the resin identification code on plastics that indicate the type of plastic resin it is made of. The wastes were heated using a semi-batch reactor for six to seven hours at 300-400 degree Celsius temperature range in which the plastic turned to plastic-derived oil and stayed in its oil state.

• Low Density Polyethylene (LDPE), High Density Polyethylene (HDPE) and Polypropylene (PP) are three most common polyolefin profusely used as packaging materials and abundantly found in the plastic waste stream.
• These plastic waste samples were collected from household waste and converted into Plastic Derived Oil (PDO) by low temperature (300 °C to 400 °C) slow Pyrolysis (long isothermal holding time) in a semi-batch reactor.
• The PDO samples obtained had shown variation in their compositions and fuel properties based on the pyrolysis temperature. PDO from the pyrolysis of PP has high octane number (∼92) and low viscosity.
• Noticeably, the PDO samples obtained at low temperature pyrolysis are lighter with low viscosity, high octane number and having high calorific values. H NMR analysis revealed that the oil samples mostly consist of paraffinic and olefinic hydrocarbons.
• Simulated distillation (SimDist) of PDO indicated that the liquid products resemble the characteristic closer to middle distillate of petroleum fraction having very low pour point and flash point.
• The temperature with long pyrolysis time also influenced the evolved gas composition and yield.
• Trace amount of hydrogen, carbon monoxide and carbon dioxide were present in the gaseous product along with various hydrocarbon gases ranging from C1–C5.
• The degradation mechanism follows end chain scission which produces monomer units whereas random scission results most of the hydrocarbon products.
• Subsequent reactions like radical recombination and inter or intra molecular hydrogen transfer results in the formation of most of the olefinic components.
• Researchers are further working on the project as more experiments need to be carried out to get a trade-off between the quality of the oil and the environmental pollution caused by the pyrolysis process.

Increasing population and rapid changing lifestyle of modern human being increases the demand of energy and at the same time significantly increases the human generated waste. Plastic wastes are abandoned and are non-biodegradable. The principal objective is to identify the optimum process parameters enabling thermochemical process to convert the plastics into energy with the aim of maximizing the yield of targeted fraction having high fuel value (gasoline or diesel).