Pyrolysis of plastic wastes to fuel oil with and without catalyst Baoying Shi, Yufeng Wang
Guangdong Dongguan Quality Supervision Testing Center Dongguan，China
School of Material Science & Chemical Engineering Tianjin University of Science & Technology Tianjin, China
Abstract—Two types of waste plastics were used in this study: polyethylene (PE) and polypropylene (PP). This paper described pyrolysis of plastic waste materials with and without catalyst. The influence of the production of liquid was investigated from plastic wastes by various catalysts. On the laboratory condition, using self-making PZSM-5 zeolite as catalyst, the yield of liquid product was highest. Key words-plastic wastes; pyrolysis; fuel oil; catalyst
pyrolysis, the polymeric materials are heated to high temperatures, so their macromolecular structures are broken down into smaller molecules and a wide range of hydrocarbons are formed. These pyrolytic products can be divided into a gas fraction, a liquid fraction consisting of paraffins, olefins, naphthenes and aromatics, and solid residues. Pyrolysis appears to be a technique that is able to convert waste plastics into gasoline-range hydrocarbons . There are four major methods for conversion of organic wastes to synthetic fuels: (1) hydrogenation, (2) pyrolysis, (3) thermal and/or catalytic cracking, (4) gasification and bioconversion [2, 3]. Literature reports several papers on pyrolysis of plastic wastes . The decomposition of a polymer mixture over HZSM-5 modified with phosphoric acid zeolite catalysts (PZSM-5) has been comparatively studied . Catalytic decomposition increased the amount of gaseous products, lowered the condensate, and changed their composition with respect to non-catalytic at the same pyrolysis temperature. The gaseous products contained a large C1～C3 fraction, while the liquid products contained mainly aromatic hydrocarbons. II. EXPERIMENTAL Two types of waste plastics were used in this study. Polyethylene (PE) and polypropylene (PP) wastes were collected from landfill in the form of cattery and they were shredded into 20mm×20mm size. A schematic representation of the simplified experimental process used is shown in Fig.Ⅰ.
In recent years accumulation of plastic wastes produced all over the world has negative implications on the environment. There can be used for ranking of different disposal processes in an environmental and resource compatible way, landfill and incineration with heat recovery. Landfill space is becoming scarce and expensive, a problem exacerbated by the fact that plastic waste is more voluminous than other waste type. Incineration on the other side, to recover energy, produces toxic gaseous products, which only shifts a solid waste problem to air pollution one. One possible alternative is the pyrolysis of plastics, one of the principal routes for recycling plastic wastes in which both energetic and chemical value of the plastics are recovered as compared to incineration in which the chemical value of the polymer is completely lost. Pyrolysis of plastic waste could have an important role in converting this waste into economically valuable hydrocarbons, which can be used as fuels in the petrochemical industry. The pyrolysis process consists of the thermal degradation of the wastes in the absence of oxygen/air. Plastics pyrolysis may provide for disposal of plastic wastes with recovery of valuable gasoline-range hydrocarbons. In
FIG.Ⅰ. SIMPLIFIED EXPERIMENT PROCESS FOR PLASTIC WASTER PYROLYSIS
Plastic samples were weight for run 100.00g and pyrolyzed in the tube. Heat to tube was supplied from external heater and the power was adjusted to give an appropriate heat up time. The simple thermocouple was placed directly in the pyrolysis medium. For each run, the heater was terminated when the desired temperature. The pyrolysis products were collected within three different groups as non-condensable gaseous...
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It is well known that PZSM-5 has the shape selectivity properties of its relatively small pore structure that does not allow the growth of large coke molecules. The liquid products from plastic wastes could be considered as a mixture of heavy naphtha, gasoline and light gas oil fractions. The gaseous products typically contain C1～C4 paraffinic hydrocarbons with some olefins. As such, most of the liquid products formed would be ideally suited to further processing in a petrochemical refinery. Currently, due to the higher oil prices, pyrolysis process is likely to be economically competitive. Moreover,
   
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