Catalytic performances of kaoline and silica alumina in the thermal degradation of polypropylene

Polypropylene was cracked thermally and catalytically in the presence of kaoline and silica alumina in a semi batch reactor in the temperature range 400℃~550℃ in order to obtain suitable liquid fuels. The dependencies between process temperatures, types of catalyst, feed compositions and product yields of the obtained fuel fractions were found. It was observed that up to 450℃ thermal cracking temperature, the major product of pyrolysis was liquid oil and the major product at other higher temperatures (475℃~550℃) are viscous liquid or wax and the highest yield of pyrolysis product is 82.85% by weight at 500℃. Use of kaoline and silica alumina decreased the reaction time and increased the yield of liquid fraction. Again the major pyrolysis product in catalytic pyrolysis at all temperatures was low viscous liquid oil. Silica alumina was found better as compared to kaoline in liquid yield and in reducing the reaction temperature. The maximum oil yield using silica alumina and kaoline catalyst are 91% and 89.5% respectively. On the basis of the obtained results hypothetical continuous process of waste polypropylene plastics processing for engine fuel production can be presented.