Plastics are some of the most useful materials ever evented by man. Plastics are found in consumer products, engineering products, automobiles, airplanes, marine vehicles etc. Since the introduction of synthetic organic polymeric products (resins and fibers) into the consumer market in the early 1950s, the global plastics production has risen from a mere 2 million metric tonnes (Mt) in 1950 to over 380 Mt by 2015. The largest application of plastics is in packaging where the volume has accelerated because of single use containers. Plastics content in municipal solid waste (MSW) has increased from 1% in 1960 to more than 10% by 2005. None of the commonly used plastics are biodegradable and accumulate in landfills or in the natural environment. The most prevalent plastics are: high density polyethylene (HDPE), low density and linear-low density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), polyvinylchloride (PVC), polyethylene terephthalate (PET), polyurethanes (PUR), polyesters, polyamide, acrylic fibers. The pure polymers are usually mixed with additives to produce desirable properties. Despite its usefulness, petroleum derived plastics have become a major pollution problem worldwide glugging gutters, rivers, oceans and landfills. The need to convert waste plastics into useful consumer products and thus reducing environmental pollution cannot be overstated. Current, recycling methods cannot solve the pollution problems. We have investigated the conversion waste plastics (HDPE, PP, PS) into fuels and aromatic compounds. The reactions were conducted under autogeneous pressure reaction conditions in temperature range of 300 to 400 C and reaction times of 15 to 30 min. The catalyst used was a proprietary catalyst formulated in-house. The ratio of water to plastic ratio (W/P) was varied from 0.2 to 10. When W/P ratio was low, the PP reaction products were mostly aromatic compounds, but when the W/P ratio was high the reaction products were mostly linear alkanes. The products from HDPE were mostly alkanes and did not contain much aromatics. The HDPE reactions were strongly affected by the reaction temperature. Analysis of the reaction products showed that the products at high temperatures will qualify as gasoline fraction whereas at lower temperatures the diesel fractions were relatively high. The yields of the liquid products were very high and the gas yield were relatively low. There was hardly any solids production in this process.
