Formation of Wax/Oil from the Batch Pyrolysis of High Density Polyethylene and Polypropylene Wastes and Resins
Roces, Susan A., Chan, David C., Yap, Kenny M., Yeung, Evan W.
De La Salle University Manila – College of Engineering Chemical Engineering Dept.
Batch pyrolysis of high density polyethylene and polypropylene has been performed in a quartz reactor to obtain waxy products. Experiments were carried out in temperatures 500, 550 & 600°C with varying sample sizes. Results showed a maximum wax/oil yield of 41 wt% for polypropylene and 34 wt% for polyethylene. Physical and chemical properties of the wax/oil products were investigated. Appearance of the wax/oil showed that at temperatures 550-600°C, the main products were highly viscous and at 500°C products were low viscous liquids. The chemical composition of the wax/oil products were mainly aliphatic hydrocarbons of up to C26 carbon atoms.
Pyrolysis is now considered an appropriate technology in dealing with waste problems, such as waste plastics. This process differs from the conventional destructive process as it allows the recovery of reaction products with added value. Having plastics subjected to this process give rise to a wider variety of products such as petrochemicals. One such source is the wax/oil formed from pyrolysis of plastic. These waxes contain calorific value and can be used as a raw material for obtaining fuels.2 This study aimed to generate wax/oil from both high density polyethylene and polypropylene wastes and resins.
The experiments were carried out using a fabricated quartz tubular reactor fitted inside an electrical furnace. An inlet stream of nitrogen flow at a rate of 50 ml/min was used for purging and also as the carrier gas for the pyrolysis product stream. The gas outlet of the reactor was connected to an ice trap consisting of a condenser and a reservoir for collection of wax/oil
References:  Aguado, Olazar, San Jose, Gaisan & Bilbao. (2002). Energy & Fuels 16, 1429.  Roces, Ashida, Pattarapanusak, Morimoto & Miura. (2006). Proceedings of the 23rd Pittsburgh Coal Conference, Pittsburgh. April 2007