Produção e caracterização do bio-óleo via pirólise a partir de diferentes cultivares do capim-elefante (Pennisetum Purpureum Schum)

Abstract

The growing global concern about climate change and the reliance on fossil fuels has driven the search for renewable energy sources. In this context, biomass has emerged not only as a sustainable alternative for energy generation but also for its ability to produce high-value-added chemical compounds. Elephant grass (Pennisetum purpureum Schum) is a promising raw material in this scenario due to its high productivity, low cost, and adaptability to different soil types, making it a versatile option for both energy and industrial applications. The thermochemical process of pyrolysis, which involves the thermal decomposition of organic matter in the total or partial absence of oxygen, generates three main products: biochar (charcoal), bio-oil (pyrolytic oil), and gases (biogas). The pyroligneous extract, which comprises a fraction of the liquid product, has broad industrial applications. Due to its complex mixture, separation and identification techniques, such as gas chromatography coupled with mass spectrometry (GC/qMS), are essential for analyzing the compounds present. In this context, the present study aimed to produce and characterize the bio-oil obtained from different genetic cultivars of elephant grass. The varieties studied were BRS Capiaçu, Madeira, and Panamá, which were subjected to thermogravimetric (TG-DTG), elemental, and proximate analyses to provide detailed characterization of the residual biomass of each genotype. The proximate analyses included determining moisture content, volatiles, ash, and fixed carbon, providing a complete profile of the biomass's physicochemical properties. Pyrolysis was carried out at specific temperatures ranging from 520°C to 550°C, depending on the biomass, with a heating rate of 10°C/min and a residence time of 60 minutes. The BRS Capiaçu genotype achieved the highest bio-oil yield (31.67%), followed by the Madeira (29.82%) and Panamá (30.22%) varieties. The compounds in the pyroligneous extract were analyzed by GC/qMS, identifying phenols and ketones as the major components, along with aldehydes, esters, and ethers. These findings expand the potential applications of bio-oil in various industrial sectors.