Navegando por Assunto "Thermal cracking"

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Acesso aberto (Open Access)
Estudo de processo de upgrading catalítico de vapores da pirólise de resíduos plásticos de equipamentos de informática em reator catalítico com carvão ativado impregnado com NaOH
(Universidade Federal do Pará, 2023-04-03) COSTA, Augusto Fernando de Freitas; MACHADO, Nélio Teixeira; http://lattes.cnpq.br/5698208558551065
This study investigated thermal cracking and catalytic upgrading of plastic waste from computer equipment on a semi-batch reactor coupled to a heated catalyst fixed bed (2-stage vapor cracking). The catalyst used was a Si–Al ash obtained from commercial activated carbon pellets treated with concentrated NaOH solution and calcination. The purpose of the study was to characterize the waste stream through its thermogravimetry (TG) analysis and pyrolysis products, study the effect of temperature (350 - 500 °C) and catalyst quantity (0.0 - 7.5 wt%) on yields of reaction products, physical chemical properties, and chemical composition of organic liquid product in order to understand and evaluate production of fuels and chemical feedstock by recycling of plastic waste from computer equipment through catalytic upgrading. Time fractioned samples were taken in determined reaction times (15 min, 30 min, 45 min, and 60 min) to study the evolution of cracking reactions during experiment runs through changes to chemical composition (GC-MS). A comparison with other previous work was also presented to show similarities between different feedstocks using the same thermal unit. The results indicate composition of brominated acrylonitrile-butadiene-styrene (Br-ABS), polycarbonate (PC), and high impact polystyrene (HIPS) for the plastic waste from computer equipment. The temperature of 350 °C produced better results when considering acid value but presented lower liquid phase yields (38 %) and high gas phase yields (42 %). Catalytic upgrading experiments revealed the increased presence of polycyclic aromatic hydrocarbons (PAH) with an increase in kinematic viscosity of organic liquid product, increase in char yield (from 11 % to 24 %), and decrease in gas yields (15 % to 5 %). Chemical composition showed presence of aromatic hydrocarbons such as styrene, methyl-styrene, and diphenyl-propane and nitrogenated compounds such as benzene butane-nitrile, phenolic compounds, polycyclic aromatic hydrocarbons, and brominated compounds. Plastic waste from computer equipment pyrolysis is a challenging subject due to contaminant presence and varying composition, and chemical composition evaluation according to reaction time provides interesting insights into the evolution of semi-batch pyrolysis/catalytic upgrading experiments. Standardization and reproducibility of the tool should be conducted to continue the evaluation of pyrolysis and catalytic upgrading of a wide range of feedstocks.
Acesso aberto (Open Access)
Estudo do processo de craqueamento térmico catalítico do sebo bovino para produção de biocombustível
(Universidade Federal do Pará, 2017-12-01) PEREIRA, Anderson Mathias; SANTOS, Marcelo Costa; http://lattes.cnpq.br/8380189608965320; MACHADO, Nélio Teixeira; http://lattes.cnpq.br/5698208558551065
This work aims to study the use of beef tallow as raw material for the production of bio fuel through the process of catalytic thermal cracking reaction. Three catalytic thermal cracking experiments were carried out in a 143 liters reactor, operating in discontinuous mode at 450 °C at atmospheric pressure, using sodium carbonate (Na2CO3) as the catalyst. Two experiments were carried out with crude beef tallow (5 and 10 % Na2CO3 - mass/mass) and one with bovine tallow soap (5 % Na2CO3 - mass/mass). The organic liquid products obtained from the reactions were analyzed through physicochemical analysis and chemical composition. Fractional distillation was also realized in order to obtain fractions of petrol, kerosene and light diesel similar to petroleum. In order to follow the reactions over time, aliquots were withdrawn every 10 minutes up to a total of 10 samples with the first point collected within 30 minutes of reaction. For the collected samples physicochemical analysis and identification of the chemical compounds were realized. The results showed a tendency to obtain higher yields in organic liquid product (OLP) using the catalyst in larger quantities with the crude sample. The chemical identification showed the amount of hydrocarbons present (paraffins and olefins) ranging from 89.28 to 92.23 % and oxygenates (ketones) from 7.77 to 10.72 %. After the distillations, a predominance was observed in the diesel fraction (235-305 °C) while the petrol and kerosene fractions were lower, this behavior was repeated in all experiments. Regarding the samples collected over the time of the reactions it is possible to verify an increase in the acidity index and formation of oxygenates up to 60/70 minutes indicating the occurrence of the primary cracking and then, until the end of the reaction, a decrease in these values evidencing the secondary cracking.
Acesso aberto (Open Access)
Investigação do processo de adsorção do carvão do caroço de açaí (euterpea olerácea mat.) obtido via craqueamento térmico
(Universidade Federal do Pará, 2022-07-04) GUERREIRO, Lauro Henrique Hamoy; SANTOS, Marcelo Costa; http://lattes.cnpq.br/8380189608965320; HTTPS://ORCID.ORG/0000-0002-2352-2050; CARVALHO JÚNIOR, Raul Nunes de; http://lattes.cnpq.br/5544305606838748; https://orcid.org/0000-0002-4433-6580
This work aims to investigate the influence of temperature and chemical impregnation on the textural and morphological composition of bioadsorbents produced via thermal cracking of açaí seeds. The experiments were carried out at 400°C and 450°C, using a pilot scale reactor. The efficiency of the process was analyzed in terms of liquid and solid products, it was verified that with the increase of the temperature of the process and with chemical impregnation with NaOH in the raw material there was a greater conversion of liquid organic product. Elementary analyzes of solid products showed how carbonization occurs with increasing process temperature and the presence of sodium due to impregnation and . The textural and morphological characterization occurred with the analysis of FT-IR, SEM/EDS, XRF and B.E.T. The solid phase product obtained by cracking the açaí seed in natura and impregnated with NaOH solution (2M), at temperatures of 400°C and 450°C. The adsorption kinetics of acetic acid investigated at 5, 10, 15, 20, 60, 120 and 180 seconds. The adsorption isotherms showed that the biochar produced at 450°C and with chemical impregnation of NaOH were able to remove acetic acid in greater amounts.