Co-pirólise de resíduos de pneus e resina polimérica presente na areia de fundição em um reator de leito fluidizado

Abstract

The use of rubber powder coming from tires through its thermal conversion, adding economic value to it through their pyrolysis products may represent a solution to the environmental problem of disposal of this waste. Two types of sand are generated in the foundry industry: sand impregnated with resin (AIR) and green sand (AV), the first being classified as hazardous waste, depending on the concentration of phenol therein. In this paper we addressed two industrial waste (tire and AIR), in order to propose a solution through co-pyrolysis in a fluidized bed reactor. The samples were subjected to several characterization tests. The AIR was characterized by determining the concentration of phenol and by Scanning Electron Microscopy (SEM). The polymeric resin was subjected to tests Spectroscopy Fourier transform infrared (FTIR) and rubbers were characterized by elemental analysis (CHNS) and immediately beyond the lower heating value. The kinetic parameters of the reaction pyrolysis of polymeric resin embedded in sand were determined by thermal analysis (TGA / DTG) under isothermal and non-isothermal. The kinetic triplet (activation energy, preexponential factor and reaction mechanism) was assessed by mathematical models of Coats-Redfern, MacCallum-Tanner and van Krevelen. Thermal analysis indicated that degradation of the polymeric resin occurs in three distinct phases. Under isothermal conditions the activation energy (Ea) and preexponential factor (A) were determined to be 61.98 kJ.mol-1 and 3.13.102 s-1, respectively. Under nonisothermal kinetics of pyrolysis of polymeric resin can be described by the mechanism Fn, for conversions below 0.8 and a diffusion process (D3) for conversions above 0.8. The co-pyrolysis of rubber (PLABOR 100/420 and PLABOR 600) and polymer resin present in AIR was performed in a fluidized bed reactor under an atmosphere of nitrogen (N2). For these experiments was used a nitrogen flow rate of 0.70 Nm3/h. Six bubblers were used for the condensation of oil produced in the process. The obtained oil and char from the pyrolysis were characterized. The main components present in the pyrolytic oil were determined by infrared spectroscopy by Fourier transform (FITR), while the char morphology was evaluated by scanning electron microscopy (SEM). In the study of co-pyrolysis, it was observed that the process is effective for removing polymeric resin contained in foundry sand as a reduction in the content of phenol after reaction. It was observed a yield of 0.46 L / kg tire (wet basis) for testing co-pyrolysis with rubber PLABOR 100/420 and 0.78 L / kg tire (wet basis) for test PLABOR rubber 600, and 10.16 g of char in the test with the rubber PLABOR 100/420 and 12.83 g in the test with the rubber PLABOR 600 for each 50 kg of rubber fed.