Pyrolysis of polypropylene(PP) Was performed to find the effects of the pyrolysis temperature(425, 450, 475 and 500℃) and the pyrolysis time(35, 50 and 65minutes), respectively. Conversion and liquid yield obtained during PP pyrolysis continuously increased with the pyrolysis temperature( up to 500℃) and the pyrolysis time(up to 65minutes), especially these were more sensitive to the pyrolysis time at 425℃ than other pyrolysis temperatures. Each liquid product formed during the pyrolysis was classified into gasoline, kerosene, light oil and wax according to the distillation temperature based on the petroleum product quality standard of Korea Petroleum Quality Inspection Institute. The liquid products of PP pyrolysis up to 450℃ were almost same fractions(26±3wt.% gasoline, 20±2wt.% kerosene and 23±2wt.% light oil) except wax(3~13wt.%). On the other hand, the pyrolysis of PP from 475℃ to 500℃ produced 26±3wt.% wax, 24±1wt.% gasoline, 18±1wt.% kerosene and 16±1wt.% light oil. After all, the main liquid product changed from gasoline to wax with increasing pyrolysis temperature.

Isothermal pyrolysis of high density polyethylene(HDPE), polypropylene(PP) and polystyrene(PS) was performed at 450℃, respectively. The effect of pyrolysis time on yield and product composition was investigated. Conversion and liquid yield obtained during HDPE pyrolysis continuously increased with time up to 80minutes, but those of PP and PS did not largely change after 35minutes. Each liquid product formed during the pyrolysis was classified into gasoline, kerosene, light oil and wax according to the distillation temperature based on the petroleum product quality standard of Korea Petroleum Quality Inspection Institute. The major liquid product of HDPE pyrolysis was light oiH34 wt.% based on the amount of HDPE treated) and the amounts of the other liquid ingredients(gasoline, kerosene and wax) were almost the same. On the other hand, the pyrolysis of PP produced 27 wt.% gasoline, 22 wt.% kerosene, 24 wt.% light oil and 13wt.% wax, and the pyrolysis of PS produced 56 wt.% gasoline, 12 wt.% kerosene, 9 wt.% light oil and 13 wt.% wax.