No abstract

No abstract

No abstract

This work studies the influence of temperature on the distribution of liquid and solid products obtained in the pyrolysis of high density polyethylene in a bubbling fluidized bed. The compositions of the products obtained vary widely depending on the operating conditions. The solid fraction (waxes) is markedly olefinic, with high molecular weight alkenes of up to sixty carbon atoms. The liquid fraction is a mixture of olefins and aromatic compounds. The gaseous fraction shows a high heating value of up to 35900 kJ/Nm3 at around 750−780 °C, and can be used for electricity generation. A limiting factor for this use is the presence of tars. The gas yield was analyzed by GC, while waxes and oils were analyzed using MS/GC. The results show that when the temperature increases, cracking of heavier olefinic fractions occurs to yield lighter fractions and higher concentrations of aromatics are obtained in the liquid fraction. The formation of polyaromatic hydrocarbons is also analyzed.

A study of the behavior of the thermal decomposition of mixtures of biomass and thermoplastics, such as polyethylene, is of interest for processes for the thermal recovery of industrial and urban wastes such as pyrolysis or gasification. No solid residue is formed during the thermal degradation of pure polyethylene. However, the addition of biomass, which generates char can vary the product distribution and increase the heating value of the gas obtained. A study of the thermal degradation of pine sawdust, polyethylene and mixtures of polyethylene and pine sawdust has been carried out in a fluidized bed reactor. Experiments were carried out at five different temperatures: 640, 685, 730, 780, and 850 ?C. The yields and composition of the derived oil, wax, and gas were determined. The addition of polyethylene increases the gas production and decreases the production of waxes and liquids for the different temperatures tested. The main gases produced from the co-pyrolysis process were, at low temperatures, carbon monoxide ethylene, carbon dioxide, propylene, butadiene, methane and pentadiene while at high temperatures the gas composition changed drastically, the main components being carbon monoxide (more than 33 wt.%), ethylene, methane benzene and hydrogen. The analysis of the liquid fraction shows a decrease of the concentration of oxygenated and aliphatic compounds.