抄録
Discarding of polyvinyl chloride (PVC) is the most problematic waste management. Thermal decomposition of PVC can lead to the production of chlorinated hydrocarbon which can result in precursors of very toxic emissions such as polychlorinated dibenzodioxins (PCDD), dibenzofuran (PCDF), and biphenyl (PCBP). Since plastic wastes are generally in a mixed form, thus, pyrolysis of mixed PVC/polypropylene(PP) was studied for the waste treatment. Pyrolysis of mixed PVC/PP at different ratios (PP:PVC =1:1, 2:1, and 3:1) were performed in a semi-batch reactor at various temperatures. The pyrolyzed oil derived from the first reactor was upgraded by NiMo/Al2O3, SiO2Al2O3, and NiMo/SiO2Al2O3 catalysts in the second reactor. The pyrolysis reaction of mixed PVC/PP had two steps. First step is the dehydrochlorination rection at temperature of 250°C. Hydrogen chloride gas from this step was absorbed in sodium hydroxide solution circulating in a gas absorber. The second step is pyrolysis reaction at 450°C. The oil products was fractionated to different boiling ranges using distillation apparatus. The gasoline fraction was analyzed for benzene, toluene, and xylene (BTX) contents by gas chromatograph. Synergistic effect on oil yield was observed in all material ratios. The PP:PVC ratio of 3:1 without catalyst provided the highest synergistic effect on oil yield with very high yield of BTX. The catalysts did not affect oil yield and all catalysts gave high gasoline yields. NiMo catalyst was selective in producing xylene compound. It was shown that NiMo on silica alumina gave the highest yield of BTX. Octane number of gasoline product was investigated by Nuclear Magnetic Resonance (NMR). The low BTX gasoline gave high octane number in the range 120-170.
