Produção de biocombustíveis a partir do óleo da polpa de macaúba: Estudo cinético

Abstract

This reports the study of the thermal and catalytic conversion of macauba pulp oil for biofuel production. The study of the use of biomass, mainly of plant origin, has been gaining notoriety when compared to other sources, due to its characteristics and its wide ease of obtaining in our country. Macauba pulp oil (Acrocomia aculeata) presents excellent results because its composition is mostly composed of unsaturated fatty acids, giving the biofuel greater stability at low temperatures, preventing freezing and oxidation of the engine, improving its performance. In order to know the chemical composition of the oil, the physicochemical parameters analyzed were: acidity index (AI): 87.5 mg KOH/g, AGL: 39.8% A.O., kinematic viscosity evaluated at 40ºC: 42.9 mm²/s, density evaluated at 15ºC: 0.924 and saponification: 195.8 mg KOH. The NiO/γ-Al₂O₃ catalyst was synthesized by the incipient wet impregnation method and subsequently characterized by the analysis techniques of X-ray Diffraction (XRD), X-ray Fluorescence Spectrometry (XRF), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA). From the data obtained, it was possible to analyze the thermal and kinetic behavior of the oil in the presence of the catalysts. In order to understand the thermal conversion process of the oil, the kinetic study was carried out using the thermogravimetric analysis technique (TGA/DTA). The kinetic study was performed using the Kissinger-Akahira-Sunose (KAS) and Ozawa-Flynn-Wall (OFW) methods in the presence and absence of catalysts, and the activation energy (Ea) was determined with values ​​between 83.37 and 167.11 kJ/mol for the pure oil, using the OFW model. A greater manifestation of the synergistic effect was observed, evidenced by the reduction in the apparent activation energy values, which varied between 62.92 and 126.89 kJ/mol for the OFW model, when the proportion of 10% of the impregnated metal to the catalytic support was used in comparison to the other catalysts. The most effective model for this study was the OFW.