Cinética da conversão térmica na pirólise de compósitos de polietileno/alumínio

Abstract

Industrial production of fuels from organic sources may follow different thermal routes such as hydrogenation, gasification and pyrolysis. Pyrolysis is widely used in industry, such as carbonization of biomass, conversion of petroleum and coal. In pyrolysis, the raw material undergoes a set of chemical reactions that are thermally induced in the partial or total absence of oxygen. Pyrolysis could be a viable route for reducing environmental impacts from polymer waste. However, the wide polymeric variety and the presence of fillers and reinforcement loads pose challenges to process control. This work studied the effects of thermal parameters on the pyrolysis of polyethylene/metallic aluminum (PE / Al) residues. Kinetic parameters were evaluated as a function of the heating rate between 10 and 40 ° C.min-1 and the possible catalytic effect of the metal charge on the polymer conversion rate. An isoconversional kinetic model was applied to the results of Thermogravimetry (TG) and Differential Exploratory Calorimetry (DSC). Thermal conversion kinetic parameters of the PE/Al composite were compared comparatively with non-aluminum polyethylene (PE) films chemically extracted from the material. Thermogravimetry (TG) determined that the mass conversion of both samples, with and without aluminum, occurred in a single volatilization step and that its maximum was directly proportional to the heating rate. The PE / Al pyrolysis product presented only the inert material while the organic material became volatile (about 92,5% of the initial mass), a fraction intended for energy purposes. The activation energies of the different samples were determined by the Starink isoconversional method, which obtained (153.8 ± 13.3) and (76.8 ± 3.6) kJ.mol-1 for PE and PE/Al, respectively. The reduction of the activation energy value for PE / Al, compared to PE, demonstrated in the present work the catalytic influence of the presence of metallic aluminum in the pyrolysis of this class of materials.