Two-Stage Thermal Gasification of Polyethylene

Toshiro TSUJI*, Yoshiki TANAKA, Toshiharu SHIBATA, Osamu UEMAKI and Hironori ITOH

Graduate School of Engineering, Hokkaido University; N13W8 Kita-ku,
Sapporo-shi 060-8628 Japan

Polyethylene pellets have been gasified by two-stage thermal degradation process. The first stage is the conversion of polyethylene to afford liquid products, and the second stage is the gasification process of the liquid hydrocarbons produced by the first-stage.
The distilled oil yield in the first stage was about 87 wt% at 470 °C. The maximum gas yield based on the weight of polyethylene in the second gasification stage was 82 wt% at 800 °C. The main components of the product gas were ethylene and methane. The optimum space time at 800 °C to obtain the gas lighter than C4 components was 2.6 s. Under these conditions, the ratio of coking was less than 1 wt%.
The two-stage pyrolyses of polyethylene produce high calorie gas efficiently with low coking ratio and some aromatic oils containing benzene, toluene and xylene as main components.

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