Pyrolysis of polypropylene for production of fuel-range products: Effect of molecular weight of polypropylene

Polypropylene (PP) with three different molecular weights (weight-average molecular weights of 12 000 (PP12); 250 000 (PP250); and 340 000 (PP340)) was pyrolyzed to investigate the effect of its molecular weight on the production of fuel-range chemicals. The pyrolytic gaseous products from the PP pyrolysis primarily consisted of non-condensable hydrocarbons such as methane, ethane, ethylene, propane, and propylene. The non-condensable hydrocarbon yields obtained with PP250 and PP340 were comparable at all tested pyrolysis temperatures (eg, 4.4 wt% at 800 degrees C) and 20% higher than the yield obtained with PP12. An increase in the pyrolysis temperature resulted in non-condensable hydrocarbon yields for all three PP plastics. In addition, hydrocarbons with wider carbon number ranges (eg, gasoline-, jet fuel-, diesel-, and motor oil-range hydrocarbons) were produced in the pyrolysis of PP. The yields of the gasoline-, jet fuel-, and diesel-range hydrocarbons obtained from PP250 and PP340 were higher than those obtained from PP12 at pyrolysis temperatures from 500 degrees C to 800 degrees C. The pyrolysis of PP250 yielded 37.7 wt% gasoline-, 38.6 wt% jet fuel-, 45.1 wt% diesel-, and 11 wt% motor oil-range hydrocarbons. The results of this study can contribute to the development of plastic waste-to-energy methods.