| Summary: | 碩士 === 文化大學 === 應用化學研究所 === 81 ===
This study investigates the reaction phenomena and the distribution of major products of pyrolysis of PET (Polyethylene Terephthalate) bottle under different heating rates. The results provide information for the design of a PET recovery system or incineration system.
From the thermal gravity analysis, PET chip pyrolyzed at temperatures above 390℃ and the faster the heating rate the higher, the incipient pyrolyzing temperature. The solid residue after pyrolysis approximates above 12%wt, the residue increases with the increasing of sample quantities and the decrease of heating rates. The dw / dt graph shows that increasing of heating rate and increasing sample amount, all result in speeding of pyrolysis. From the appearance of the pyrolysis residue, one can tell the PET chip melts to a viscous fluid and bubbled by the pyrolyzing gas to form a hollow fragile shell, which might cause difficulties on the discharge of these residues from the pyrolzer. The residue contains 80 ~ 90% of carbon and 1.4 ~ 2.4% of hydrogen, it will be burn completely in air at 700℃. The residue was determined as amorphous by x - ray diffraction, and it contains trace amount of metals such as Sb、Ca、Al、Co、Si、Mg、Sn、Cu、Mn, Co and Cu. The componetns of vapor phase condensate collected in ice bath were analyzed by GC / MS and the main components are benzoic acid and its derivatives, which are easily being recovered.
Pyrolyzed gas was also analyzed by the mass spectro - graphy, the spectra were not affected by the heating rate as well as the retention time, M / Z peaks appear at 44, 43, 29, 28, 27, 26, 25, 18, 16, 15, 14, 13 and 12. other gas products appear in M / Z as multiplied derivatives of monomers. It suggests that the pyrolysis mechanism is the same regardless of the heating rates.
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