Estudo do processo de pirólise de caroços de açaí Í (Euterpe oleracea Mart.) em escala piloto para produção de biocombustíveis

Abstract

The objective of this work was to study the process of bio-oil production through the pyrolysis of raw acai kernel on a pilot scale, focusing on the yield of products obtained at temperatures of 350°C, 400°C and 450°C at 1 atm. In addition to studying the results obtained via gas chromatography coupled to mass spectrometry (GC-MS) of the bio-oils produced. For the experimental procedure, the raw material used was the açaí pits, a residue obtained after the process of pulping the fruit. This material went through stages of drying, comminution and sieving to remove unwanted residues for the process. This material was characterized by determining the moisture content, volatile content, ash content, fixed carbon content and higher calorific value. After the characterization process, the lumps were submitted to the pyrolysis process and, after the due separation processes, the bio-oil obtained was submitted to tests to determine its acidity index, absolute density, refractive index, and dynamic viscosity. After this step the bio-oil was subjected to analysis in a gas chromatograph coupled to a mass spectrometer. The moisture content found in the açaí seeds was approximately 40% and the yield of the pre-treatment step was 46.84%. In the physical characterization of the seeds the results found were within the existing literature showing interesting properties for use in the pyrolysis process. With the increase in temperature there was a favorable production of bio-oil and biogas, while for the biochar there was a decrease in its mass produced. The physicalchemical analyses applied to the Bio-Oil produced were within the values that are available in the literature for this same type of material, however, it is still outside the standards that the National Petroleum Agency establishes for green diesel. The increase in temperature reduced the acidity of the bio-oil and increased its viscosity and density. With this, there was a reduction 92.87 (Exp.1) to 70.26 (mg of NaOH/g of sample) (Exp.3) and the lowest kinematic viscosity obtained of 77.62 mm²/s for the pyrolysis process with the temperature set up to 350°C. The chromatographic analysis showed that the compound with the highest percentage of peak area was phenol, where the average retention time was 8,466 min-1 independent of the programmed temperature. Exp.2 had the highest yield in terms of aromatic hydrocarbons and the lowest yield for phenols, showing that there is no linear behavior with temperature change.