Investigation on degradation of polyethylene to oils in supercritical water

To obtain basic knowledge on degradation of polyethylene (PE) to oils in supercritical water, effects of reaction temperature, reaction time, water/PE ratio and water filling rate on degradation of PE to oils were investigated in supercritical water with a 125-ml autoclave. Reaction conditions were in the range of temperature 450-480 degreesC, time 1-30 min, water/PE ratio 2/1-10/land water filling rate 25-40%. The experimental results showed that the yield of oil was decreased with an increase of temperature and extension of reaction time, while yield of gas was increased. H2O/PE ratio not only affected the yield of products, but also changed the composition of oil products. From increasing productivity of unit volume of reactor, H2O/PE ratio of 2-4 was reasonable. The effect of water filling rate on oil yield was not significant. The oil yield of degradation of PE to oils was more than 90 wt.% under reaction temperature of 460 degreesC, reaction time of 1 min and water/PE ratio of 6. It provided the basic data for development of a process of continuous degradation of PE to oils. (C) 2004 Elsevier B.V. All rights reserved.