Obtenção de bio-óleo rico em levoglucosana a partir da pirólise rápida de diferentes biomassas

Abstract

The severity of the damage caused to the environment by the inclusive use of physical sources requires that human beings take a new look at the future of the world energy matrix. In this scenario, residual lignocellulosic biomasses are a cheap, renewable and widely available resource. The conversion of biomasses into bio-oil appears as an alternative to petrochemicals, with great potential for the production of high value-added chemicals, such as levoglucosan, an important platform chemical product. In this work, the pyrolysis of three different biomasses, sugarcane straw (SC), banana straw (PB) and brewer's exclusion (MT), was studied in order to produce bio-oil rich in levoglucosan. The biomasses were identified by different techniques, including chemical characterization, X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA). They were subjected to micropyrolysis and fast pyrolysis in a bench reactor. The results of chemical characterization of different contents of lignin, cellulose and hemicellulose for the tested biomasses. The three main zones of destruction of the biomasses were identified in the TGA curves: drying, active pyrolysis zone and charcoal formation. From the micropyrolysis, various organic compounds such as alcohol, aldehydes and anhydrous sugars with relative area above 15% were specific, among which was levoglucosan. The expressive production of anhydrous sugars by the MT biomass was also observed, being for this reason selected for acid pretreatment, in order to maximize the yield of this class of compound. Thus, the MT sample was pretreated with HCl 1 mol/L and the bio-oil obtained was analyzed by Nuclear Magnetic Resonance (NMR) and FTIR. The FTIR spectra for the in natura MT bio-oil samples presented estimates of the hydroxyl groups (-OH) characteristic of phenols, carboxylic acids and alcohols, as well as C-O and C-H elongations of aliphatic and phenolic methyls, common in lignin destruction products. The NMR spectra showed peaks at 80 ppm, indicating the presence of anhydrous sugars in both the in natura biomass bio-oil samples and the pre-treated biomass derivative, demonstrating that the pre-treatment was able to enhance the release of this class of compounds, contributing to the valorization of the selected residue.