Influência dos extrativos hidrofílicos de biomassas nas composições dos bio-óleos e a possibilidade de aplicação ao petróleo

Abstract

Among the various techniques available for biomass transformation, pyrolysis has attracted much attention for the efficient conversion of lignocellulosic biomass (cellulose, hemicellulose and lignin) into solid, liquid and gaseous products by thermal decomposition. The bio-oil obtained from the pyrolysis of biomass is used as fuels and chemical products and both its yield and its composition depend on the type of biomass and the operational parameters of the process. This work has the objective to investigate the influence of hydrophilic extractives on the yield and composition of bio-oil obtained from the pyrolysis of biomass from sisal residue, sugarcane bagasse and eucalyptus residue. These extractives were analyzed by FTIR and GC-MS in order to obtain a better understanding of their constituents. Micropyrolysis experiments were also carried out at 550°C of the original biomass, the extracted biomass and their respective extractives. Extraction with water and ethanol had a significant effect on the composition of the bio-oils produced. The sisal residue had an extractive content of up to 69.3%, which contributed to the formation of a significantly higher proportion of long-chain aliphatic hydrocarbons and nitrogen compounds, distinct from other residues. The content of alkanes and alkenes in the original sisal waste bio-oil was 17.2% and 19.1%, while they decreased to 0.8% and 15.9% for the extracted biomass, respectively. The pyrolysis of extractives in sugarcane bagasse and eucalyptus residue formed some long-chain fatty oxygenates and fewer nitrogenous compounds. The bio-oils derived from these two biomasses contained oxygenates as dominant compounds, however, they had a smaller fraction of heavy components and lower oxygen contents compared to the bio-oil from sisal residue. While bio-oils derived from sugarcane bagasse and eucalyptus residue exhibited higher aldehyde contents, around 23%, bio-oil from sisal residue contained approximately 47% hydrocarbons. Finally, extractives also had an influence on CO2 concentration, as evidenced by notable variations in the range of 52.6% to 75.3% of this compound during the pyrolysis of biomass extractives. Therefore, most of the alkanes in the oil derive mainly from the decomposition of triglycerides and hydrocarbons existing in biomass extractives. The results may be useful to study the origin of alkanes and benzene derivatives in oil obtained from biomass by fast pyrolysis.