Search Results (3)

The most efficient technique for resolving the issue of plastic waste disposal is by converting the wastes into high-quality liquid oils through thermal and catalytic pyrolysis. The objective of this work was to study the composition of liquid oils obtained by thermal and catalytic degradation of plastic wastes containing polystyrene (PS), polyvinyl chloride (PVC), and polyethylene terephthalate (PET). The clay catalysts were characterized by N₂ adsorption–desorption isotherms (BET), Scanning Electron Microscopy (SEM) and Fourier transform Infrared Spectrometry (FTIR), Polarized Optical Microscopy (POM), Atomic Force Microscopy (AFM). The effect of temperature and clay catalyst type on the yields of the end-products resulting in thermo-catalytic degradation of PS has been evaluated. Degradation of PS showed the highest liquid oil production at 86.85% in comparison to other plastic types. The characterization of the liquid oils was performed by comprehensive two-dimensional gas chromatography coupled with single quadrupole mass spectrometry (GC × GC-qMS). In liquid oils of PS, eighteen principal compounds (of groups: linear hydrocarbons, mono-aromatics, and di-aromatics) were identified. In the liquid oils of the plastic waste mixture, twenty-four principal compounds (of groups: linear hydrocarbons, mono-aromatics, oxygen-containing aromatic, di-aromatics, and tri-aromatics) were identified. The liquid oils were investigated in order to reconvert them as styrene monomers or other chemicals in energy recovery. Full article

Thermochemical recycling of plastics in the presence of catalysts is often employed to facilitate the degradation of polymers. The choice of the catalyst is polymer-oriented, while its selection becomes more difficult in the case of polymeric blends. The present investigation studies the catalytic pyrolysis of polymers abundant in waste electric and electronic equipment (WEEE), including poly(acrylonitrile-butadiene-styrene) (ABS), high-impact polystyrene (HIPS) and poly(bisphenol-A carbonate) (PC), along with their blends with polypropylene (PP) and poly(vinyl chloride) (PVC). The aim is to study the kinetic mechanism and estimate the catalysts’ effect on the activation energy of the degradation. The chosen catalysts were Fe₂O₃ for ABS, Al-MCM-41 for HIPS, Al₂O₃ for PC, CaO for Blend A (comprising ABS, HIPS, PC and PP) and silicalite for Blend B (comprising ABS, HIPS, PC, PP and PVC). Thermogravimetric experiments were performed in a N₂ atmosphere at several heating rates. Information on the degradation mechanism (degradation steps, initial and final degradation temperature, etc.) was attained. It was found that for pure (co)polymers, the catalytic degradation occurred in one-step, whereas in the case of the blends, two steps were required. For the estimation of the activation energy of those degradations, isoconversional kinetic models (integral and differential) were employed. In all cases, the catalysts used were efficient in reducing the estimated E_α, compared to the values of E_α obtained from conventional pyrolysis. Full article

A good way to make carbon materials was presented in low-temperature polyvinyl chloride (PVC) carbonization by catalysis. The process of low-temperature PVC carbonization by CuAl-layered double hydroxide (CuAl-LDH) was investigated by thermogravimetric analysis (TGA) and tubular furnace. The results show that CuAl-LDH accounting for 5% of PVC mass enabled acceleration of the dehydrochlorination in PVC as soon as possible and maximized the yield of the PVC carbonized product. The vacuum with 0.08 MPa, 20 °C/min heating rate and 90 min carbonized maintenance time were optimal for PVC carbonization. Moreover, the best morphology and yield of the carbonized product was provided at a carbonization temperature of 300 °C. Full article