Mestrado em Engenharia Química (IQ)
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Item Sistemas catalíticos heterogêneos para reações de acoplamento Stille-Migita(Universidade Federal de Goiás, 2019-08-27) Godoy, Pedro Henrique Machado; Oliveira, Guilherme Roberto de; http://lattes.cnpq.br/8239498431579015; Alonso, Christian Gonçalves; http://lattes.cnpq.br/7285754665946583; Alonso, Christian Gonçalves; Ostroski, Indianara Conceição; Chagas, Rafael Pavão dasCarbon-carbon coupling reactions are of fundamental importance in the synthesis of organic compounds. The Stille-Migita reaction is a cross-coupling reaction and occurs when an organotin compound and an organic halide hybridized to sp3 react under the presence of a metal-based catalyst, generally palladium. The reaction has the advantage of being compatible with virtually any functional group and for forming products with complex chains, such as pharmaceuticals and agrochemicals. However, Stille synthesis is usually performed by homogeneous catalysis, which enhances the need for costly purification processes necessary to remove metal debris from the reaction products. Thus, this work synthesized and verified the use of heterogeneous catalysts for Stille coupling reactions, using the efficient and economical method of wet impregnation in its preparation by producing monometallic catalysts with different oxides as support. The catalysts were characterized before and after calcination by thermogravimetry and differential thermal analysis (TG / DTA), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), textural analysis by adsorption/desorption isotherms of N2 and X-ray fluorescence (XRF). The reaction parameters were optimized: time, temperature, type of solvent and catalyst composition. The materials La2O3/Pd and TiO2/Pd showed no catalytic activity, whereas the catalysts Nb2O5/Pd and SiO2/Pd showed good conversions, above 80%. The recycling tests showed considerable loss of activity, which could be associated with filtration and leaching of the active phase between cycles. Nb2O5/Pd showed higher efficiency in the presence of non-toxic solvents (water/ethanol), unusual in Stille reactions. It is expected that this work will contribute to the development of heterogeneous catalysis, particularly in the coupling reactions, since economical methods of synthesis have produced catalytically active materials.Item Catalisadores a base de Cu, Ni e Mg suportados em Al2O3 aplicados à gaseificação de etanol em meio contendo água em condições supercríticas(Universidade Federal de Goiás, 2018-09-28) Melo, Jarbas Almeida de; Souza, Thiago Leandro de; http://lattes.cnpq.br/7431199944070783; Alonso, Christian Gonçalves; http://lattes.cnpq.br/7285754665946583; Alonso, Christian Gonçalves; Souza, Thiago Leandro de; Santos, Dyrney Araújo dos; Queiroz Júnior, Luiz Henrique KengIn this work the synthesis of catalysts was carried out with the objective of H2 production from gasification of ethanol in medium containing water under supercritical conditions. Based on reports from the literature, Cu, Ni and Mg were selected as components for the active phase, alumina (Al2O3) as catalysts support. The catalysts were prepared from aqueous solutions of nitrate salts precursors of Cu, Ni and Mg. The catalysts were characterized by X-ray fluorescence (FRX), scanning electron microscopy, thermogravimetric and thermal differential analysis (TG/ATD), X-ray diffraction (DRX) and textural analysis by N2 adsorption / desorption isotherms at -196 ° C. The TG/ATD analysis indicated that the calcination of the catalytic precursors was sufficient for the removal of water and decomposition of the nitrates of the metal salts precursors of the active phase. In the FRX analysis, the increase in the concentration of the metals in relation to the nominal values after the synthesis of the catalysts was characterized, with an increase of 20 to 40% depending on the metal due to the loss of water from the alumina support. The FRX analysis of the catalysts used in the catalytic tests shows that there was no significant leaching during the gasification process. DRX analysis have characteristic results that the metals are in amorphous form or dispersed in the form of small crystallites. Textural analysis of N2 adsorption / desorption isotherms indicated a reduction of approximately 60% in the specific surface area between the alumina and the calcined alumina and the specific area values between the alumina and the metal catalysts were kept close. The catalytic tests were performed at a pressure of 25 MPa and at temperatures of 400 to 650 ° C. A 10/1 molar water / ethanol solution was fed. In the catalytic tests H2, CH4, CO, CO2, C2H4, C2H6, C2H4O were obtained. The highest ethanol conversions were obtained at the temperature of 650 ° C for the catalysts NiO/Al2O3 and NiO-MgO/Al2O3, both 81%. The highest yield was 0.41 mol H2 / mol ethanol fed to the NiO / Al2O3 catalyst, at a temperature of 600 ° C. The highest selectivity at the temperature of 600 ° C was 39%, obtained by the NiO/Al2O3 catalyst.Item Catalisadores heterogêneos aplicados à reação de Biginelli(Universidade Federal de Goiás, 2017-03-07) Nascimento, Letícia Gomes do; Oliveira, Guilherme Roberto de; http://lattes.cnpq.br/8239498431579015; Alonso, Christian Gonçalves; http://lattes.cnpq.br/7285754665946583; Alonso, Christian Gonçalves; http://lattes.cnpq.br/7285754665946583; Oliveira, Guilherme Roberto de; http://lattes.cnpq.br/8239498431579015; Andrade, Fabiano Molinos de; Arroyo, Pedro AugustoThe Biginelli reaction involves the cyclocondensation of three reagents in the presence of an acid catalyst to obtain dihydropyrimidinones (DHPMs).This compound and its analogues are widely known to possess various pharmacological properties, such as antibacterial, antiinflammatory, antifungal, antiviral, anticancer and antihypertensive. This reaction is usually carried out via homogeneous catalysis, which presents, however, some difficulties, such as regeneration of the catalyst and difficult separation of the final product, thus becoming an obstacle for industrial use. In the present work, it was proposed the use of two classes of heterogeneous catalysts, which are: metal oxides and acid carbons in order to achieve attractive characteristics in the Biginelli reaction, as a reduction of reaction time and increase in yield. The acidic carbons were prepared by carbonization by impregnation of agroindustrial residues with sulfuric acid at a temperature of 200 °C in the mass ratio of 1:10 (precursor: H2SO4) for 6 h. The pure HY-340 and Nb2O5 were both tested and chemically treated with a solution of 30% sulfuric acid. The catalysts were characterized by X-ray diffraction (XRD), infrared spectroscopy (FTIR), thermogravimetric (TG), differential thermal analysis (DTA), textural adsorption/desorption analysis of N2 at -196 °C and desorption of ammonia at programmed temperature (DTP-NH3), scanning electron microscopy (SEM) and X-ray Dispersive Energy Spectrometry (EDS). The contents of C, N, O and S present on the surface of the coals were quantified by Elementary Analysis (CHNS-O). Exploratory catalytic tests were carried out to define the best experimental conditions of solvent, temperature, molar ratio and amount of catalyst. The results obtained allowed to establish the best experimental conditions for the realization of the Biginelli reaction. Thus, the following parameters were adopted to evaluate the performance of the different catalysts. These are: 5% catalyst content (by mass), molar ratio of 1 Benzaldehyde: 1,5 Methyl acetoacetate: 1,5 Urea, without solvent and temperature of 130 °C. The best catalyst was Nb2O5 treated with sulfuric acid, whereby a yield of 94% of dihydropyrimidinones (DHPMs).Item Desenvolvimento e avaliação de sistemas catalíticos heterogêneos para reações de acoplamento carbono-carbono de Suzuki-Miyaura(Universidade Federal de Goiás, 2019-02-21) Souza, Guilherme Botelho Meireles de; Oliveira, Guilherme Roberto de; http://lattes.cnpq.br/8239498431579015; Alonso, Christian Gonçalves; http://lattes.cnpq.br/7285754665946583; Alonso, Christian Gonçalves; Oliveira, Guilherme Roberto de; Ostroski, Indianara Conceição; Chagas, Rafael Pavão das; Matos, Ricardo Alexandre Figueiredo deSuzuki-Miyaura cross-coupling reactions are one of the most efficient and powerful tools for the formation of new carbon-carbon bonds, which have been widely applied in modern organic synthesis and industrial processes. Generally, these reactions are carried out by homogeneous catalysis, employing expensive palladium complexes such as PdCl2 associated with harmful phosphine ligands. However, these synthetic route presents several drawbacks such as high associated toxicity, catalyst recovery difficulties and waste disposal problems. In this context, several heterogeneous catalysts were proposed to overcome the great challenge of separation and recovery of homogenous catalysts. Also, a low-cost catalyst was presented as an alternative for the usage of palladium as the main Suzuki-Miyaura cross-coupling catalyst. Palladium, Nickel, Copper and Cobalt catalysts supported on niobium pentoxide (Nb2O5) were synthesized via wet impregnation method and tested for the Suzuki-Miyaura coupling reaction between phenylboronic acid and 4- bromoanisole. The catalysts were well characterized by scanning electron microscopy, N2 physisorption, X-ray diffraction, X-ray fluorescence, Thermogravimetry/Differential Thermal Analysis. Both Copper and Cobalt catalyst did not show any activity towards Suzuki- Miyaura cross-coupling reaction. Palladium catalyst resulted in high isolated yields (up to 91%) under optimized conditions. Satisfactory yields (up to 48%) were achieved employing the Nickel catalyst. Recycling tests were performed and significant loss in activity was observed after the first catalytic cycle, which can be attributed to catalyst loss during its retrieval by filtration between cycles, leaching of the active phase, in particular for Pd/Nb2O5 catalyst, or the poisoning by inorganic species (mostly potassium) on the spent catalyst’s surface.Item Produção de hidrogênio a partir de efluente do processo de fabricação de biodiesel(Universidade Federal de Goiás, 2022-12-21) Teixeira, Isabela Rodrigues; Andrade, Laiane Alves de; http://lattes.cnpq.br/6777831109573242; Alonso, Christian Gonçalves; http://lattes.cnpq.br/7285754665946583; Alonso, Christian Gonçalves; Andrade, Laiane Alves de; Souza, Thiago Leandro de; Oliveira, Sérgio Botelho de; Souza, Guilherme Botelho Meireles deThe growing energy demand witnessed stems from the way industrial production processes developed from 1970 onwards with the so-called new industrial revolution. This high demand provoked an escalation in the production of fuels, having been supplied, since then, mainly by fossil fuels. The use of this type of energy source results in the emission of compounds into the atmosphere such as Carbon Dioxide (CO2) and other gases that, if released in large quantities, cause environmental imbalances such as the global warming. Such a scenario reveals the need for an energy transition. The gradual transition from carbon-based fuels to low or no-emissions would contain a likely energy crisis. Recent studies indicate that hydrogen (H2) has great potential as one of the sources capable of complementing the high demand, being a source of clean and sustainable energy. As a result, the treatment of industrial waste aimed at transforming it into clean energy has been quite attractive, since in addition to generating a by-product of great economic value, it also reduces the problem of final disposal. Thus, the present work aims to evaluate the production of H2 from the effluent of the biodiesel industry in a medium containing water under supercritical conditions in a continuous flow reactor, verifying the effect of temperature and feed flow variation on the production of hydrogen and/or synthesis gas generated by the process, performing statistical planning in order to optimize the production of H2 through the Central Composite Design (CCD). The independent variables analyzed were the Feed Flow (Qa) and the Temperature (T) with the temperature varying between 500 and 700 °C and the feed flow between 10 and 25 mL/min. Hydrogen represented the highest percentage among the gases generated in the process, the best condition indicated a percentagem (molar fraction) for H2 of 73.86%, for a temperature of 700°C. Proportionally, the second highest generation gas was CO2, with the highest percentage of 22.39% for a temperature of 529°C. The highest value for gas flow was 5540.80 mL/min (T of 700ºC and Qa of 17.55 mL/min). The response variable studied statistically was the average gas flow (mL/min) compared to the H2 flow (mL/min). The analyses indicated a significant increase in the generation of H2 and gasification of the sample with the increase in temperature, while the feed flow did expressed less influence in relation to the analyzed ranges, but showed a tendency to increase the production of H2 for higher feed flow values. To verify the efficiency of the treatment of the effluent in the supercritical environment, the load of Total Organic Carbon (TOC) and other parameters of the raw effluent were compared with the reduction of these after-treatment. The raw effluent sample that initially had a TOC load of 48250.0 mgC/L, after being subjected to treatment via the supercritical process, showed a greater TOC reduction of 82.62% for test 2, with a Qa of 12. 25 mL/min and temperature of 671°C, in addition to significant reductions in the analyzed parameters, in compliance with national environmental legislation, showing that the process using biodiesel industrial effluent as raw material is efficient for the production of hydrogen and also for its treatment. The use of a homogeneous catalyst based on hydrogen peroxide (H2O2) in order to intensify treatment for removal of TOC showed an improvement in the removal of the organic load of 4.13%.Item Catalisadores heterogêneos para produção de chalconas: reação de condensação de Claisen-Schmidt(Universidade Federal de Goiás, 2016-03-07) Winter, Caroline; Pérez, Caridad Noda; http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4792149E3; Alonso, Christian Gonçalves; http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4777466U2; Alonso, Christian Gonçalves; Pérez, Caridad Noda; Machado, Nádia Regina Camargo Fernandes; Oliveira, Guilherme Roberto deThe members of flavonoids and chalcones family have attracted great interest because of their pharmacological applications as antibacterial, anti-inflammatory and anticarcinogenicagents, and are commonly synthesized by Claisen-Schmidt condensation between acetophenone and benzaldehyde derivatives. This reaction is usually catalyzed under homogeneous conditions which present, however, several drawbacks such as catalyst recovery and waste disposal problems. This work proposes the use of a variety of heterogeneous catalysts to achieve good results for condensation Claisen-Schmidt reaction in terms of conversion and chalcones selectivity, when compared to the homogeneous catalysis. Two groups of catalysts were tested: metal oxides and activated carbons. Magnesium oxide catalysts were prepared by hydrothermal treatment and magnesium, niobium, lanthanum and titanium oxides by rehydration of commercial precursors, all methods followed and not followed by cesium impregnation. The activated carbons used as catalysts were Babassu, Bahia Coconut, ox bone and Dendê, raw and treated with sodium hydroxide. The catalysts were characterized by scanning and transmission electron microscopy, thermogravimetric analysis, differential thermal analysis, determination of the specific superficial area by the adsorption/desorption of N2 at 77 K method, infrared spectroscopy, X-ray diffraction and temperature-programmed desorption of CO2 and NH3. The basic sites of carbons were quantified by Boehm Method. Finally, the performance of the catalysts was evaluated on the Claisen-Schmidt reaction between Acetophenone and 4-nitrobenzaldehyde, and the conversion was quantified by high performance liquid chromatography. The best catalyst was treated babassu activated carbon, whose conversion achieved was 92,38%.