This study investigated thermal cracking and catalytic upgrading of plastic waste from computer
equipment on a semi-batch reactor coupled to a heated catalyst fixed bed (2-stage vapor
cracking). The catalyst used was a Si–Al ash obtained from commercial activated carbon pellets
treated with concentrated NaOH solution and calcination. The purpose of the study was to
characterize the waste stream through its thermogravimetry (TG) analysis and pyrolysis
products, study the effect of temperature (350 - 500 °C) and catalyst quantity (0.0 - 7.5 wt%) on
yields of reaction products, physical chemical properties, and chemical composition of organic
liquid product in order to understand and evaluate production of fuels and chemical feedstock by
recycling of plastic waste from computer equipment through catalytic upgrading. Time fractioned samples were taken in determined reaction times (15 min, 30 min, 45 min, and 60
min) to study the evolution of cracking reactions during experiment runs through changes to
chemical composition (GC-MS). A comparison with other previous work was also presented to
show similarities between different feedstocks using the same thermal unit. The results indicate
composition of brominated acrylonitrile-butadiene-styrene (Br-ABS), polycarbonate (PC), and
high impact polystyrene (HIPS) for the plastic waste from computer equipment. The temperature
of 350 °C produced better results when considering acid value but presented lower liquid phase
yields (38 %) and high gas phase yields (42 %). Catalytic upgrading experiments revealed the
increased presence of polycyclic aromatic hydrocarbons (PAH) with an increase in kinematic
viscosity of organic liquid product, increase in char yield (from 11 % to 24 %), and decrease in
gas yields (15 % to 5 %). Chemical composition showed presence of aromatic hydrocarbons
such as styrene, methyl-styrene, and diphenyl-propane and nitrogenated compounds such as
benzene butane-nitrile, phenolic compounds, polycyclic aromatic hydrocarbons, and brominated
compounds. Plastic waste from computer equipment pyrolysis is a challenging subject due to
contaminant presence and varying composition, and chemical composition evaluation according
to reaction time provides interesting insights into the evolution of semi-batch pyrolysis/catalytic
upgrading experiments. Standardization and reproducibility of the tool should be conducted to
continue the evaluation of pyrolysis and catalytic upgrading of a wide range of feedstocks.
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