Estudo de bio-óleos de sorgo biomassa obtidos via pirólise catalítica rápida

Abstract

In this study, catalytic fast pyrolysis of three different strains of biomass sorghum was carried out to obtain bio-oil (liquid fraction). The hemicellulose (26.00; 26.12 and 24.66% w/w) cellulose (37.95; 38.88 and 32.88% w/w) and lignin (6.54; 4.52 and 3.91% w/w) present in each species was determined by van Soest extraction process. To verify the main decomposition profile of these raw materials, a preliminary study of thermal degradation was performed using different thermal analysis techniques. Thermogravimetric technique (TG) and the derived mass loss (DTG), which showed the dominant presence of two main peaks, the first at a range of 165-205 oC and the second, more intense, between 260- re ated to ce u ose decomposition. The decomposition of lignin takes place in a wider range of 200- Pyrolysis of biomass 716 impregnated with ZnO (5-20% w/w) and without catalyst were carried out in a vertical reactor at a temperature of 500 oC with a heating rate of 200 oC/min, and a nitrogen flow top and bottom 150 and 80 mL/min, respectively. Pyrolysis of biomass 716 using zeolite as the catalyst, were performed after planning design leading to a total of 19 experiments. The experiments were carried out randomized to optimize the parameters such as heating rate (oC/min), nitrogen flow (mL/min), the amount of biomass (g) and an amount of catalyst (% w/w) to obtain a bio-oil with minor amounts of oxygenates. The characterization of the bio-oil obtained was performed by gas chromatography coupled to a mass spectrometry (GC/MS), who showed that both bio-oils derived from biomass with or without zinc oxide consist mainly of oxygenates, with the majority phenolics. As for the experiments with biomass 716 impregnated with zeolite (5-30% w/w) was observed the emergence and increase of hydrocarbons, which showed the potential use of this catalyst to obtain a bio-oil rich in this kind of compounds. Planning design revealed that the response variables that were significant to the desired response were the amount of biomass and catalyst. Thus, it was possible to create a response surface from these two variables, which gave a critical minimum, showing that for this biomass is favorable for the production of a rich bio-oil oxygenates, which are widely used in the biorefinery. Then, another surface was created with phenolic compounds (majority) as the response variable and thus obtained a maximum critical point given by 13.5% (w/w) of catalyst and 15.2 g of biomass to obtain a content of 59% (area) phenolics.