Production of oil and gas through thermal and thermo-catalytic pyrolysis of waste polyethylene

Abstract

Waste polyethylene is one of the most abundant plastics coming to the municipal waste. Polyethylene releases toxic chemicals, which deteriorate the environment and human health. This study investigates the valorization of waste polyethylene through thermal and thermo-catalytic pyrolysis process. Being low cost and reusable, the ordinary Portland and white cements were used as a catalyst. The thermal, white cement catalyzed, and Portland cement catalyzed pyrolysis produced 83.16%, 90.99%, and 89.61% relative amount of oil, respectively, at optimum temperature of 500 °C. For time optimization, the pyrolysis reaction was carried out for different time intervals between 15 and 78 min. The catalyst weight of 30% was found best option for increasing the hydrocarbon yield and cutting down the reaction time and is deemed as ensuring the economic disposal of the waste polyethylene. The oil product was broken down into fractions with boiling points comparable to gasoline, kerosene, and diesel and some residual fraction. The gaseous product was analyzed through different chemical analysis and combustibility tests. The oil product was analyzed using FT-IR and GC–MS techniques. It was observed that the oil product is composed of alkane and alkenes. The oil products of catalytic and thermal processes exhibited different chemical compositions. The number of compounds and their nature varied with a change in pyrolysis approach.