EXPERIMENTAL-DETERMINATION OF THE YIELD OF PYROLYSIS PRODUCTS OF POLYETHENE AND POLYPROPENE - INFLUENCE OF REACTION CONDITIONS

The influence of temperature, residence time, concentration level of r eactants and products, polymer type, and composition of the polymer mi xture on the product spectra obtained from pyrolysis of polyethene (PE ) and polypopene (PP) was determined. In our study the temperature was varied between 650 and 850 degrees C, whereas residence times between 0.1 and 1 s were used. Thermodynamic calculations revealed that aroma tics and methane are formed as the main products under conditions pert aining to chemical equilibrium. The ratio between these compounds is g overned by the C/H ratio in the original polymer. Experiments were per formed using a tubular reactor. The main products of the pyrolysis of PE and PP at 750 degrees C and a residence time of 1 s are ethene (res pectively 45 and 19 wt %), propene (24 and 45 wt %), and butene (23 an d 27 wt %). At higher reactor temperatures the yields of ethene and me thane increase, while the yields of both propene and butene decrease. The influences of the residence time, product concentration, polymer t ype, and composition of the polymer mixture on the product distributio n are negligible compared to the influence of temperature.