Steam gasification of polyethylene terephthalate (PET) with a focus on investigating effects of calcium oxide, recycled feedstock and bed material
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Insinööritieteiden korkeakoulu |
Master's thesis
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Authors
Date
2023-10-09
Department
Major/Subject
Sustainable Biomass Processing
Mcode
Degree programme
Environomical Pathways for Sustainable Energy Systems
Language
en
Pages
50+1
Series
Abstract
Plastic pollution is still a problem as it causes negative environmental health effects, and the increasing demand for plastics contributes to the increase of greenhouse gas emissions. Polyethylene Terephthalate (PET) is a type of plastic commonly used to manufacture beverage bottles, various household containers, single use take-away packaging etc., and while mechanical recycling technology is relatively mature, there is still a significant amount of PET that reaches its end of life in landfill or incineration plants. Gasification is one promising thermochemical method to recover useful products from end-of-life PET. This work investigated the effects of calcium oxide feedstock types, and bed material types on product yields from steam gasification of PET, which have not been studied in previous research. A bubbling fluidized bed gasifier was used, and the products (gas, tars, and solid residue) were analyzed. The results showed that in the presence of CaO, higher gas yield and lower tar yield were obtained due to the catalytic effect of CaO on steam reforming of tar. When recycled PET granulates or flakes were used, the gas yields did not vary significantly compared to virgin PET, which means our previous research regarding virgin PET could be directly applied to recycled PET. When CaO was in the bed instead of being fed with PET, the hydrogen yield was higher. Compared to CaO, calcined dolomite seems less effective in boosting hydrogen yield, probably due to its lower mechanical strength which leads to fragmentation and elutriation. All these insights could subsequently be incorporated in future modelling and experimental studies, and larger scale applications on steam gasification of PET.Description
Supervisor
Järvinen, MikaThesis advisor
Li, ShouzhuangInayat, Muddasser
Keywords
steam gasification, PET, CaO, hydrogen, tar, CO2