Navegando por Assunto "Biofuels"

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Acesso aberto (Open Access)
Decomposição catalítica do glicerol em fase vapor usando a perovskita cecuxni1-xo3 (x=0;0.25) como precursor catalítico
(Universidade Federal do Pará, 2017-03-09) ESTRADA, Marcial Antonio Fuentes; FRANÇA, Luiz Ferreira de; http://lattes.cnpq.br/6545345391702172; RIBEIRO, Nielson Fernando da Paixão; http://lattes.cnpq.br/0755443458423442
The utilization of the fuels fossils like main source of energy has carried to the generation of countless environmental and economic problems, creating the need of diversification of the energetic matrix. In Brazil, country with vast territorial extension and agroindustry very established stands out the production of biofuels, such as: ethanol and biodiesel. Particularly, the production of biodiesel with the increasing governmental incentives exponentially has its production increased to each year placing Brazil in prominence in the worldwide scene of biofuels. In the process of transesterification of vegetal oils with a primary alcohol, beyond biodiesel, the rude glycerin in a ratio of 10% is generated 11% in volume. The bio refining of the deriving glycerin of the manufacture of biodiesel, becomes the production of biodiesel economically more viable, leading to the formation of products with raised aggregate values. For this reason, the present work has as main objective the valuation of the chain of production of biodiesel for the transformation of glycerol to the products of bigger value added through reaction catalytic decomposition of glycerol using perovskitas of the CeNi1-xCuxO3 type (x=0 and 0,25) as you will catalyze. The gotten results had shown that the use of high temperature (500 °C) favors the gas production of synthesis with approach relation H2/CO of 1, this occur for the strong craqueamento of the molecule of glycerol, At 410 ° C and inert reaction atmosphere, hydroxyacetone (acetol) was the major product exhibiting selectivity in the range of 22-28% depending on the catalyst used. The effect of the addition of hydrogen on the reaction load was investigated and its insertion promoted the hydrogenation of the hydroxyacetone, leading to an increase in selectivity for 1,2-propanediol whose selectivity varied in the range of 4-9% depending on the catalyst.
Acesso aberto (Open Access)
Estudo da aplicação da lama vermelha como catalisador na reação de craqueamento térmico catalítico de resíduos de caixas de gordura
(Universidade Federal do Pará, 2015-07-02) EID, Janaina Guedes; BORGES, Luiz Eduardo Pizarro; http://lattes.cnpq.br/8756886156388456; MACHADO, Nelio Teixeira; http://lattes.cnpq.br/5698208558551065
This study aimed to evaluate the use of residual fat taken from retaining grease traps as an alternative raw material in the biofuel production process. The catalytic process of thermal cracking of the residual fat was carried out in bench scale and pilot using the red mud (LV) calcined at 1000 ° C as catalyst at different concentrations (5%, 10% and 15%). Organic liquids (PLO's) obtained in the cracking experiments were distilled in a bench unit, which was the production of hydrocarbon fractions in bands of light green diesel and heavy green diesel. Thus, PLO'se fractions were characterized by carrying out physicochemical and compositional analysis where the results turned out to be compared according to the specifications established by the standard of ANP No. 65 for diesel S10. The produced in the PLO counter and cracking unit using the pilot content of 5% catalyst (LV calcined at 1000 ° C) when compared with experiments using concentrations of 10% and 15% of LV showed the best results for the acid value, kinematic viscosity and density, confirming that this experiment had one of the best yields of the process and significant results regarding the physicochemical and compositional analysis. Distillation processes of the PLO's done in the distillation unit in Bench Scale showed good yields for hydrocarbon fractions in heavy green diesel range. The heavy green diesel fractions obtained after distillation of the PLO produced with 5% catalyst content showed significant yield and the best physicochemical results of all fractions obtained in this study, especially with regard to the acid value. It was confirmed through analysis of the Infrared, nuclear magnetic resonance, and gas chromatography coupled to a mass spectrometer the presence of hydrocarbons in the composition of the organic liquids.
Acesso aberto (Open Access)
Estudo da obtenção de biocombustíveis a partir da rota tecnológica de craqueamento utilizando carbonato de sódio e lama vermelha como catalisadores
(Universidade Federal do Pará, 2013-12-26) OLIVEIRA, Romero Moreira de; MOTA, Silvio Alex Pereira da; http://lattes.cnpq.br/2688995977218366; MACHADO, Nelio Teixeira; http://lattes.cnpq.br/5698208558551065
In this paper the crude distillation process of the liquid organic product obtained in the catalytic cracking of oil palm (Elaeis guineensis, Jacq) was studied in pilot scale , using the sodium carbonate (Na2CO3) and red mud catalysts by varying the percentage of catalyst in 10% m/m and 15% m/m for the raw material used , an operating temperature of 450ºC in order to obtain fractions of biofuels (bio-gasoline, bio-kerosene and bio-oil) similar to fuels derived from being fixed oil. The catalysts were subjected to a dehydration pre-treatment for 2 hours in an oven at 300°C, subsequently the XRD, IR and TG were performed. Regarding raw materials, physical and chemical analysis, aiming to characterize palm oil were performed. The organic liquid products (PLOs) were subjected to unit operations of separation, decanting and simple filtration bench scale should then be performed physical-chemical and compositional analyzes. The temples were distilled in a Vigreux column six (06) stages, and the condensed fractions were collected according to the ranges of the distillation of gasoline (60ºC - 190ºC) , kerosene (190ºC - 235ºC ) and diesel (235°C - 370°C), later to be characterized. There was a better catalyst efficiency for sodium carbonate 15% w/w as reducing the acid value about 1.7 mgKOH/g , and a conversion of 97% by weight of the oil in PLO was noted also, by increasing the amount of catalyst that favors the obtaining of an end product with better quality. The red mud on the other hand, showed yields of up to 64% m/m products with a low acidity of about 62.90 mgKOH/g, comparing this result with literature data. Based on the final results verified the efficiency of catalysts, the catalyst which sodium carbonate gave products with low acidity and good characteristics for use as fuel.
Acesso aberto (Open Access)
Estudo de viabiliade econômica do processo de pirólise e craqueamento termo-catalítico em escala piloto utilizando-se material ligno-celulósico, lipídico, de óleo de palma (elaeis guineensis, jacq) e resíduo da neutralização do óleo de palma
(Universidade Federal do Pará, 2022-12) AMARAL, Anderson Rocha; SANTOS, Marcelo Costa; http://lattes.cnpq.br/5640587707776287; MACHADO, Nélio Teixeira; http://lattes.cnpq.br/5698208558551065
In this work, it is accomplished a tecno-economic assessment of the production of bio-oil, coke and gas, via thermos-catalytic pyrolysis followed by distillation. The raw materials were: lipid-base material (residual fat/scum from fat retention box of the University Restaurant at the Federal University of Pará - UFPA), lignin-cellulosic material Açaí seed (Euterpe oleracea. Mart), palm oil and neutrilzing sludge palm oil. From the literature is made a review of the physic-chemical analysis of the raw materials, of the bio-oil and of chemical composition of the biofuels produced (biogasoline, bioquerosene, light-diesel and heavy-diesel). Are also presented the bio-oil yields for each experiment of pyrolysis and distillation and compared with the literature. The economic indicators demonstrated feasibility of the all projects, with exception with the use of açaí seeds. The indicators used to analysis the projects were: a) simple payback criterion, b) discounted payback, c) net present value (NPV), d) internal rate of return (IRR), and e) index of profitability (IP). The minimum fuel selling price (MFSP) obtained is this work for the biofuels was of 1.34 US$/L for all projects, with exception to the palm oil, which was 1,59 US$/L. The sensibility analysis demonstrated that the pyrolysis and distillation yields are the most important variables to affect the minimum fuel selling price (MFSP).
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)
Estudo do processo de craqueamento termocatalítico da borra de neutralização do óleo de palma para produção de biocombustível
(Universidade Federal do Pará, 2015-04-17) SANTOS, Marcelo Costa; BORGES, Luiz Eduardo Pizarro; http://lattes.cnpq.br/8756886156388456; MACHADO, Nélio Teixeira; http://lattes.cnpq.br/5698208558551065
The Soap phase residue derived from refining vegetable oils are agro-industrial residues obtained after the neutralization stage of vegetable oils, which are aggregate low-value material, in addition to being an environmental liability for agribusiness thus is becoming increasingly attractive the use of these residues as raw material for generation bio-fuels. This work studies the neutralization sludge of palm oil as an alternative raw material, from the point of view, economic and environmental to the process of catalytic and Thermic-catalytic cracking. Initially were carried experiments of Thermic and catalytic cracking of the neutralization sludge and palm oil (in one reactor) and catalytic tests (the second reactor coupled in the first decarboxylation) both in bench scale; experiments were perfomed of the thermic-catalytic and catalytic (only in semi-pilot scale) of the neutralization sludge in the semi-pilot and pilot scale using different types of catalysts (Na2CO3, CaCO3, activated alumina, zeolite HY, HZSM-5, and FCC). The organic liquid product (OLP) obtained and the fractions obtained from the distillation in bench and pilot scale were characterized and compared with the current standard. The results obtained in laboratory scale have shown that the activated alumina catalyst provided the highest yield in wet basis (83.70%), with palm oil as raw material, however, the bio-fuel obtained Na2CO3 had a better quality how much the physicochemical characteristics. . In the semi-pilot scale, the highest yield was the thermal experiment of the sludge (78.36%), followed by the experiment with 5% activated alumina (71.47%), but the use of Na2CO3 showed better quality in the how much the physicochemical characteristics.The experiments in the pilot scale showed the highest yield (71%) obtained with 15% Na2CO3 at a temperature of 440 ° C. The results of the chromatographic analysis of this OLP obtained in the pilot scale confirmed that the percentage increase in the catalyst enabled the formation of a OLP rich in hydrocarbonate (91.22%) containing aliphatic, olefinic, naphthenic, aromatic and low amounts of oxygenates (8 , 78%). While in the distillation of PLO of the Experiment 5 makes possible to get fractions rich in hydrocarbons and without oxygenates compounds.
Acesso aberto (Open Access)
Estudo do processo de craqueamento termocatalítico do óleo de palma (Elaeis guineensis) com lama vermelha calcinada e alumina ativada em reatores de bancada e batelada
(Universidade Federal do Pará, 2015-05-29) LOURENÇO, Rafael Martins; BORGES, Luiz Eduardo Pizarro; http://lattes.cnpq.br/8756886156388456; MACHADO, Nelio Teixeira; http://lattes.cnpq.br/5698208558551065
In the present work was to study the thermal catalytic cracking process palm oil for biofuel production. In the development of this study were performed in crackings Bench and Semipilot. Initially, basic catalysts in cracking tests were performed (Red Mud; Red Mud Calcined at 550 ° C; Red Mud Calcined at 800C; Red Mud Calcined at 1000 ° C; Activated Alumina (AA) with NaOH 20% solution and Activated Alumina (AA) NaOH solution 30%) and acid (not activated alumina) in bench scale using as raw palm oil. Before the mentioned catalysts are used in thermal catalytics crackings, they were subjected to the following tests: Fourier Transform Infrared (FT-IR); Scanning Electron Microscopy (SEM); X-ray Diffraction (XRD) and BET in order to characterize them. The results of the bench scale showed that the cracked products Gross (PCB's) achieved in thermal catalytics oil crackings using as a catalyst 15% Red Mud Calcined at 800 ° C and 15% AA by NaOH 20% solution, had a significant reduction in their Acidity Index (IA's) compared to the IA's of heat and thermal catalytics crackings used with other catalysts. In Semipilot Scale the thermal catalytics crackings were developed with the best results obtained, Bench Scale, between the Red Mud’s Calcined or not in different concentrations (15% of Red Mud Calcined 800 ° C) and between the Activated Aluminas or not at various concentrations (AA with 15% NaOH solution at 20%) compared to IA's, in addition to the thermal cracking which was also reproduced on the scale. Some of the products obtained in Semipilot Scale was submitted to distillation in Bench Scale to obtain fractions corresponding to the tracks: gasoline, kerosene, light diesel and heavy diesel. The RMN analysis of 13C, held on the heat crackings and diesel thermal catalytic with 15% Red Mud Calcined at 800 °C proves that they are basically formed from long chain fatty acids. Moreover, the GC-MS performed in the cut of gasoline range (40 °C- 175 °C) showed that the three gasolines analyzed showed the formation of paraffinic hydrocarbons, olefinic and naphthenic.
Acesso aberto (Open Access)
Estudo do processo de pirólise de caroços de açaí Í (Euterpe oleracea Mart.) em escala piloto para produção de biocombustíveis
(Universidade Federal do Pará, 2022-06-27) BAIA, Ana Cláudia Fonseca; 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
The objective of this work was to study the process of bio-oil production through the pyrolysis of raw acai kernel on a pilot scale, focusing on the yield of products obtained at temperatures of 350°C, 400°C and 450°C at 1 atm. In addition to studying the results obtained via gas chromatography coupled to mass spectrometry (GC-MS) of the bio-oils produced. For the experimental procedure, the raw material used was the açaí pits, a residue obtained after the process of pulping the fruit. This material went through stages of drying, comminution and sieving to remove unwanted residues for the process. This material was characterized by determining the moisture content, volatile content, ash content, fixed carbon content and higher calorific value. After the characterization process, the lumps were submitted to the pyrolysis process and, after the due separation processes, the bio-oil obtained was submitted to tests to determine its acidity index, absolute density, refractive index, and dynamic viscosity. After this step the bio-oil was subjected to analysis in a gas chromatograph coupled to a mass spectrometer. The moisture content found in the açaí seeds was approximately 40% and the yield of the pre-treatment step was 46.84%. In the physical characterization of the seeds the results found were within the existing literature showing interesting properties for use in the pyrolysis process. With the increase in temperature there was a favorable production of bio-oil and biogas, while for the biochar there was a decrease in its mass produced. The physicalchemical analyses applied to the Bio-Oil produced were within the values that are available in the literature for this same type of material, however, it is still outside the standards that the National Petroleum Agency establishes for green diesel. The increase in temperature reduced the acidity of the bio-oil and increased its viscosity and density. With this, there was a reduction 92.87 (Exp.1) to 70.26 (mg of NaOH/g of sample) (Exp.3) and the lowest kinematic viscosity obtained of 77.62 mm²/s for the pyrolysis process with the temperature set up to 350°C. The chromatographic analysis showed that the compound with the highest percentage of peak area was phenol, where the average retention time was 8,466 min-1 independent of the programmed temperature. Exp.2 had the highest yield in terms of aromatic hydrocarbons and the lowest yield for phenols, showing that there is no linear behavior with temperature change.
Acesso aberto (Open Access)
Processo de Transformação termoquímica dos cachos sem frutos de dendê (Elaeis guineensis, Jacq)
(Universidade Federal do Pará, 2016-05-12) RABELO, Rafael Farias; FRANÇA, Luiz Ferreira de; http://lattes.cnpq.br/6545345391702172
The biomass thermal processing is an important operation to add value to the generated waste by palm oil industries. The objective of this work was to monitor the temperature influence (400, 500, 600 and 700°C) and the particle size in the thermal processing of palm fruit bunches without (PFB). It was used an apparatus for thermal processing containing a 4,4x10-4 m3 reactor, with possible recovery of solid and liquid products. The raw materials used were composed with PFB fractions of different particle size (entire sample (without screening), coarse fraction (retained on a 28 mesh sieve), mean fraction (retained on 60 mesh sieve) and fine fraction (retained in the sieve bottom)), which were properly characterized by immediate analysis, lignocellulosic composition, thermogravimetric and higher calorific power. In the solid products, it was made immediate analysis and higher calorific power value, on the other hand, in the liquid products, it was measured the higher calorific power, the density, the kinetic viscosity and the pH values. The solid maximum efficiency occurred at 400°C temperature, the gaseous product at 700°C temperature and the liquid had equivalent values at temperatures of 400, 500 and 600°C. The experiments raw materials showed lignocellulosic values between 45 to 53% of cellulose, 17 to 23% of hemicellulose and 30 to 40% of lignin in their composition. The thermogravimetric analysis showed higher degradation percentages at 300°C temperature, indicating a higher weight loss relative to the cellulose. The solid product showed higher percentages of fixed carbon and lower volatile percentages at 600 and 700 °C temperatures, also showed significant gains on the calorific power value, the results varied from 40.57 to 55.04% for the entire sample, from 56.74 to 70.12 % for coarse fraction, from 44.22 to 54.25% for mean fraction and 32.77 to 45.52% for fine fraction. The liquid product also showed significant gains in the calorific power value, the results varied from 56.48 to 68.59% for the entire sample, from 71.69 to 85.00% for coarse fraction, from 54.76 to 66.28% for mean fraction and 46.42 to 63.31% for fine fraction. Density values, kinematic viscosity and pH decreased with particle size reduction of PFB.
Acesso aberto (Open Access)
Produção de biocombustíveis em diferentes escalas via craqueamento térmico catalítico de resíduos de caixa de gordura com catalisador Na2CO3
(Universidade Federal do Pará, 2015-07-03) CORRÊA, Onésimo Amorim; BORGES, Luiz Eduardo Pizarro; http://lattes.cnpq.br/8756886156388456; MACHADO, Nelio Teixeira; http://lattes.cnpq.br/5698208558551065
This paper presents the residual fat taken from retaining grease traps as a potential feedstock for the production of alternative and renewable fuels. The residual oil was used as filler in experiments catalytic thermal cracking countertop units, Semi-pilot and pilot. Different levels of sodium carbonate (5%, 10% and 15%) were used as a catalyst in the catalytic thermal craqueamneto experiments. Organic liquids (PLO's) obtained in the cracking experiments were distilled in distillation units in bench and pilot scale. Distillation processes resulted in the development of hydrocarbon fractions in kerosene bands, light and heavy diesel. The PLO's with the green light and heavy diesel fractions were characterized according to the specifications established by the standard of ANP 65 for diesel S10. The green kerosene fractions were characterized according to the specifications established by the standard of ANP 37 for petroleum-based kerosene. The results showed that the PLO's had low values for the acid value, moreover, it was confirmed that the use of different percentages of catalyst ash in the three scales of production contributed to obtaining promising results in terms of yield and physico -chemical and compositional, indicating the efficiency of this basic catalyst. The results also showed that the fractions of green kerosene, heavy and light green diesel had low levels of free fatty acids, significant income and physical and chemical characteristics in line with their respective standards. The experiments using the percentage of 10% sodium carbonate as catalyst showed the highest incomes, lower levels of acidity and the best results of physicochemical and compositional characterization of all the tests in this study. The PLO produced using the level of 10% of sodium carbonate showed a total of 78.98% of hydrocarbons in the composition, while the green kerosene obtained after distillation of the same PLO showed 92.64% total hydrocarbons in its composition, these results were confirmed by analysis as FT-IR, RMN and GC-MS.
Acesso aberto (Open Access)
Produção de biocombustíveis um craqueamento termo-catalítico de gordura residual com lama vermelha ativada quimicamente como catalizador
(Universidade Federal do Pará, 2019-12-04) OLIVEIRA, Romero Moreira de; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968; MACHADO, Nélio Teixeira; http://lattes.cnpq.br/4688021995450878
In this work, a biofuels study was carried out by the pilot scale thermo-catalytic cracking process, of the residual fat from the fat boxes of the university restaurant of the Federal University of Pará (RU-UFPA), using activated red mud as a catalyst. The residual fat used in the experiments was treated by sieving, decantation, dehydration and storage, to be introduced into the cracking reactor. The red mud was subjected to a pre-treatment of dehydration in an oven at 100°C for 24 hours, then subjected to a chemical treatment with 0,5M, 1M and 2M hydrochloric acid solution (HCl). Subsequently calcination of this material was carried out at 1000°C for 2 hours, to be applied as a catalyst in the proportions 5%, 10% and 15% m/m. The cracking process was performed at a fixed temperature of 550°C, and the generated PLO was collected by reaction time 10 at 20, 40, 60 and 80 minutes, these were then characterized and subjected to fractional distillation. Distillation was performed on a Vigreux column with 12 stages, and condensed fractions were collected according to the distillation ranges of gasoline (45°C-175°C), kerosene (175°C-235°C), light diesel (235°C-305°C) and heavy diesel (>305°C), to be characterized later. The highest yield (PLO + gas) was from experiment 5 with 90%, prepared with 15% m/m catalyst treated with 1M HCl. Also presenting biofuels with better physical-chemical characteristics such as the acid value of gasoline in point 4 (9,4 mg KOH/g) and composites with the highest of 92.91% of total hydrocarbons for kerosene.
Acesso aberto (Open Access)
Produção de biocombustíveis via craqueamento térmico-catalítico de resíduos sólidos de caixas de gordura com carbonato de sódio e lama vermelha ativada termicamente
(Universidade Federal do Pará, 2015-04) ALMEIDA, Hélio da Silva; MENDONÇA, Neyson Martins; http://lattes.cnpq.br/7534816053779593; MACHADO, Nélio Teixeira; http://lattes.cnpq.br/5698208558551065
This work has the main objective to study the production of biofuels from Thermal-Catalytic Cracking process pilot scale using residual fat removed from the grease traps of the university restaurant of Universidade Federal do Pará (RU-UFPA). The residual fat was collected and treated by sifting, dewatering and separating and introduced into the cracking pilot unit. Were used as catalysts soda ash and red mud thermally activated at 1000 ° C, reject material from the production of alumina Hydro-Alunorte company, which also is an environmental liability. After cracking the organic liquid product obtained was distilled and characterized in the laboratory and pilot scales, obtaining the biofuel Biokerosene band, biogasoline, light and heavy diesel. Additionally, it was investigated the consumption of drinking water of that restaurant and the generation of wastewater, determining the per-capita water consumption, the coefficient of sewage return, the pollution load and the population equivalent. The PLO higher yield of around 82% was obtained with 15% sodium carbonate catalyst. The acid value of the PLO (14.97 mg KOH / g) showed a figure considered low and very satisfactory when compared with the values obtained in the literature. The chromatographic results of the experiment with 10% sodium carbonate showed high content PLO hydrocarbons (78.98%), green kerosene (92.64% of oil) and light diesel (90.21% hydrocarbons). The results denote viability in the production of biofuels from the treated residual fat of the fat boxes.
Acesso aberto (Open Access)
Propriedades Térmicas do (Bio)Butanol e a Fotocatálise do Grafeno com Trifenilamina Dopado com Metais para Geração de H2
(Universidade Federal do Pará, 2019-01-10) MARTINS, Marcelo Gonçalves; CHAVES NETO, Antonio Maia de Jesus; http://lattes.cnpq.br/3507474637884699
In this study, the optical properties and electronic structures of the transition metal-doped G-TPA using water as solvent were theoretically investigated in order to evaluate the efficiency in the production of photocatalytic hydrogen. in the Gaussian 09W software, using the B3LYP functional for all structures, and the base 6-31g (d) for the H, C and N atoms, and the LANL2DZ base, applying the effective potentials method for the transition metals (Ni, Pt, Pd, Fe, Os). Through the DOS of each structure an increase of accessible states in the valence layer was observed, as well as the decrease of the gap for all doping and for the structure with two and three radicals of triphenylamine. Through the UV-vis absorption spectrum, there was an improvement in absorption in the range of 490 nm to 615 nm. Another analysis carried out in the sense of energy generation was the evaluation of the thermodynamic potential of the butanol properties as complementary fuel or substitute for conventional fuels. For this, the Gaussian09W allied to the DFT was used again, but combined with the functional ones, hybrid B3LYP with the base set 6-311 ++ G (d, p) and 6-31 + G (d), G3 and G4 , in addition to the CBS / QB3 compounds. The simulations were carried out and the thermodynamic properties were found, such as: the specific molar heat at constant pressure, the enthalpy of formation and the entropy. All the properties were obtained between the temperatures 100K - 1500K and constant pressure of 1atm, in addition the enthalpies of combustion of the butanol isomers were obtained, several ternary mixtures were also proposed where it was possible to compare the enthalpy variations between the fuels: gasoline, ethanol and n-butanol.
Acesso aberto (Open Access)
Propriedades termodinâmicas: querosene, bioquerosene, aditivos e mecanismos de detecção de explosivos
(Universidade Federal do Pará, 2018-11-23) MORAES, Edimilson dos Santos; CHAVES NETO, Antonio Maia de Jesus; http://lattes.cnpq.br/3507474637884699
In this work we perform the characterization of thermodynamic potentials, obtaining predictions based on Density Functional Theory and statistical thermodynamics, through the canonical ensemble model. The study compared two theoretical methods, B3lyp/6-311 ++ g(d, p) and the semi-empirical method PM3, with the experimental values of the thermodynamic property of CP with the objective of validating the method with better precission. All simulations were performed conformation of the global minimums and optimizations of the molecules in thermal equilibrium and for a temperature range of 0.5 - 1500 K. We will analyze the thermal properties, such as energy, enthalpy, Gibbs free energy, entropy, heat capacity at constant pressure with respect to temperature. In the combustion enthalpy the following methods were used: B3lyp/6-311 ++ g(d, p), B3lyp/6- 31+g(d), CBS-QB3, G3, G4 and the G3 / G4 mean, obtaining results that show a good agreement with the experimental values, and verifying which of the methods best predicts the thermodynamic properties for reactions of combustion of the kerosene and bioquerosene. Also, a theoretical analysis was performed in DFT to calculate the thermodynamic properties of three molecules of additives. We simulated a composition of JP-8 with mixtures of the three additives together and separated in order to observe its efficiency over other existing methods. Then, the thermodynamic properties of the gasoline with additives were predicted under the same conditions already described. These calculated amounts included standard gasoline mixed with the following oxygenated additives: methyl tert-butyl ether, ethyl tert-butyl ether, diisopropyl ether, ethanol and methanol. It is possible to estimate some relevant fuel properties in the injection and combustion stage, showing substantial agreement with the experimental data, presenting relative errors of less than 2%, thus establishing an excellent method to calculate and predict the thermodynamic properties of the combustion reactions for with additives. In the last stage of this work, we present a theory of a simulated sensor device to identify explosive molecules that is of extreme interest for the area of public security in the fight against terrorism. For this, an armchair-type carbon nanotube (CNT) was modeled under the action of an external, longitudinal and uniform electric field, causing the molecules of the explosives: 2,4,6 trinitrotoluenes, triacetin triperoxide, hexogen, hexamethylene triperoxide diamine, octogen and pentaerythritol tetranitrate. Turn around the CNT, behaving as a sensor depending on the temperature and the radius of rotation of the molecules. In this way, we study the physico-chemical properties of the interactions of the molecules with the CNT.
Acesso aberto (Open Access)
Teoria do funcional de densidade aplicada a reatividade química de combustíveis e biocombustíveis na fase gasosa: gasolina, etanol e gasolina-etanol
(Universidade Federal do Pará, 2015-03-10) GOMES NETO, Abel Ferreira; CHAVES NETO, Antonio Maia de Jesus; http://lattes.cnpq.br/3507474637884699; MACHADO, Nelio Teixeira; http://lattes.cnpq.br/5698208558551065
We performed a theoretical study using the Density Functional Theory, with the B3LYP functional and the basis set 6-311 ++ g (d,p) to calculate thermodynamic properties of the following fuels and biofuels: gasoline, ethanol and gasoline-ethanol mixture, all in gas phase. The simulations were performed using the Gaussian 09W and Hyperchem 7.5 softwares and allowed obtaining fuel properties, witch, were calculated from the weighted average for the properties to each of its major components, considering the mass fractions of components of two kinds of gasoline, a Standard kind and other commercial Regular. The simulations were performed at various temperatures in the range 0.5K - 1500K and under pressure of 1 atm, using continuous polarizable model to simulate solvated systems with each component. Conformational search, optimization and frequency calculations (Raman and Infrared) were simulated were performed, where, was possible obtain physical quantities associated with the chemical reactivity and the calorific value of the fuel during injection phase in combustion chamber. It was also possible to prove and quantify some relevant characteristics of the fuels, such as, The high antiknock potential of ethanol when it is compared to the gasoline, as well as the influence caused for the ethanol when blended with gasoline. These comparisons were made from the study of thermodynamic potentials (internal energy, enthalpy and Gibbs free energy) obtained during the simulations. In addition to these properties, were calculated the rate-change of Gibbs free energy in relation to temperature, specific heat at constant pressure and entropy of major components. This methodology has been reproduced using the PM3 and PM6 semi-empirical computational methods with the purpose of comparing its accuracy and computational cost to the study fuels, to results obtained from the B3LYP functional. We found that semi-empirical methods can generate results with a good precision for calculations of thermodynamic properties of major components, as such as, functional B3LYP showed, but with a computational cost far lower enabling this work presents itself as a methodology quite effective for the thermodynamic characterization of fuels and biofuels in the gas phase, when they are injected into the combustion chamber.