Catalytic process toward green recycling of polyvinyl chloride: A study on thermodynamic, kinetic and pyrolysis characteristics

Abstract

Municipal solid wastes (MSW) include a considerable amount of polyvinyl chloride (PVC). How to quickly and harmlessly dispose of the PVC-containing MSW and convert them into a valuable resource is an urgent issue at present. The application of catalysts has yet been proven to be effective in mitigating organic pollutant production. In the present study, a thermogravimetric analyzer (TGA) and pyrolysis-gas chromatography-mass spectrometer (Py-GC/MS) were utilized to investigate the thermodynamic properties, kinetic parameters and pyrolysis characteristics of PVC with different zeolites including HZSM-5 with the Si/Al of 80 and 280, ferrierite, HY and MCM-41 zeolite. It turned out that the introduction of different catalysts with different pore structures and acid site concentrations made different catalytic effects on the cracking mechanism of PVC. Among the five zeolites, MCM-41 decreased temperature at the 50 % conversion to 296 °C, increased weight loss mate at a maximum of 25 %/min and generated fewer PAHs (whose changing amplitude decreased by 94 % in ex-situ catalytic mode in comparison to non-catalytic mode), indicative of its higher catalytic activity in PVC polymer degradation. Under the consideration of maximizing catalytic cracking activity and minimizing secondary pollutants production, non-catalytic dechlorination at approximately 300 °C followed by catalytic degradation in ex-situ mode over mesoporous MCM-41 at higher temperatures was the best recommendation.