Navegando por Assunto "Chemical activation"

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Acesso aberto (Open Access)
Caracterização da fase aquosa e bio-óleo produzidos na pirólise das sementes e fibrasde açaí (Euterpe Oleracea Mart.)
(Universidade Federal do Pará, 2024-09-24) SOUSA, Erick Monteiro de; MACHADO, Nélio Teixeira; http://lattes.cnpq.br/5698208558551065; MACHADO, Nélio Teixeira; http://lattes.cnpq.br/5698208558551065
Açaí (Euterpe oleracea Mart.) is a native fruit of the Amazon, and its production chain is centered in the state of Pará. The processing of açaí fruits generates large amounts of solid waste, which can pose serious risks to the environment if not used and managed properly. The novelty of this research lies in the fact that until this moment, no research had been reported in the literature on the pyrolysis of açaí fibers and the chemical composition of the aqueous phase, making possible a broad set of applications including biogas production. The present research proposes a study of the pyrolysis of açaí seeds and fibers and the physicochemical and compositional characterization of the aqueous phase products. In this way, açaí processing residues were collected in the city of Belém, PA. The seeds and fibers were dried and impregnated with NaOH solutions, and subsequently subjected to pyrolysis on a laboratory scale. The liquid products from pyrolysis were characterized through acidity index analysis, FT-IR, and gas chromatography. The increase in the concentration of the impregnating agent led to an increase in bio-oil yield from both the seeds (ranging from 3.3% to 6.6%) and the fibers (ranging from 1.2% to 3.7%). The yield in the aqueous phase showed an inverse behavior, decreasing as the concentration of NaOH increased, both in the seeds (ranging from 41% to 37.5%) and the fibers (ranging from 33.7% to 21.2%). High acidity levels were found in the liquid products studied, which decreased as the concentration of the impregnating agent increased. The increase in the concentration of the impregnating agent (NaOH) influenced the chemical composition of the obtained liquid products, leading to a decrease in oxygenated compounds and an increase in nitrogenous compounds in both experimental matrices, which was also evidenced by the reduction in acidity
Acesso aberto (Open Access)
Estudo do processo de upgrading catalítico de vapores da pirólise de gordura residual em reator de leito fixo com catalisador carvão ativado impregnado com NAOH
(Universidade Federal do Pará, 2022-08-17) BERNAR, Lucas Pinto; MACHADO, Nélio Teixeira; http://lattes.cnpq.br/5698208558551065; BORGES, Luiz Eduardo Pizarro; http://lattes.cnpq.br/8756886156388456
This work investigated influence of reaction time and catalyst-to-residual fat ratio by catalytic upgrading from pyrolysis vapors of residual fat at 400 °C and 1.0 atmosphere, on the yields of reaction products, physicochemical properties (density, kinematic viscosity, and acid value) and chemical composition of bio-oils, over a catalyst fixed bed reactor of activated carbon pellets impregnated with 10.0 M NaOH, in semi pilot scale. The experiments were carried out at 400 °C and 1.0 atmosphere, using a process schema consisting of a thermal cracking reactor of 2.0 L coupled to a catalyst fixed bed reactor of 53 mL, without catalyst and using 5.0, 7.5, and 10.0% (wt.) activated carbon pellets impregnated with 10.0 M NaOH, in batch mode. Results show yields of bio-oil decreasing with increasing catalyst-to-feed ratio. The GC-MS of liquid reaction products identified the presence of hydrocarbons (alkanes, alkenes, ring-containing alkanes, ring-containing alkenes, and aromatics) and oxygenates (carboxylic acids, ketones, esters, alcohols, and aldehydes). Physico-chemical and compositional analysis show that cracking occurred along the carbon chain present in triglycerides and fatty acids initially present, producing gaseous hydrocarbons. Tha activated carbon catalyst was not selective for the liquid biooil deoxygenation, but the obtained results are of great value for understanding the catalytic cracking reaction mechanism.