Recovery of Gasoline-Range Hydrocarbons from Petroleum Basic Plastic Wastes

A solid waste management system based on the 3R principle: reduce, reuse, and recycle. There are two major recycling methods for conversion of plastic wastes to synthetic fuels: (a) pyrolysis in absence and presence of catalyst and (b) thermal and/or catalytic cracking. Pyrolysis is a complex series of chemical and thermal reactions to decompose or depolymerize organic material under oxygen-free conditions. The most affecting variables of plastic pyrolysis are catalyst type and shape, temperature, and residence time. Certain types of waste plastics such as polystyrene (PS), polyethylene (PE), and polypropylene (PP) are generally used in pyrolysis. The plastic wastes can be pyrolyzed into liquid, gas, and solid residue products. The pyrolysis of plastic wastes produces a whole spectrum of hydrocarbons including paraffins, olefins, naphthalenes, and aromatics. The total yields of paraffins and olefins of PE and PP wastes obtained by pyrolysis were higher than that of PS. The oil obtained from plastic pyrolysis could improve performance by modifying engine. The addition of catalyst in the pyrolysis can be a more efficient method to produce high valuable products with mainly gasoline-range hydrocarbons. The catalytic decomposition was produced much more light hydrocarbons than that of thermal decomposition. Especially, ZSM-5 with a smaller pore size, rather than that of zeolite Y was more cracked into light hydrocarbons such as C₆-C₁₂ hydrocarbons and gas products.