Browsing by Author "Lima, Ana Carolina Coelho"
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- Evaluation and kinetic study of alkaline ionic liquid for biodiesel production through transesterification of sunflower oilPublication . Lima, Ana Carolina Coelho; Hachemane, Khadidja; Ribeiro, António E.; Queiroz, Ana; Gomes, Maria Carolina Sérgi; Brito, PauloBiodiesel production is performed in the industry by alkaline transesterification of oils with a low amount of free fatty acids. In order to reduce the disposal of conventional catalysts used industrially, ionic liquids (ILs) have been studied to be applied as catalysts in transesterification since they can be recovered and reused in subsequent reaction cycles. In this work, the ionic liquid choline hydroxide (ChOH) was successfully applied as a catalyst for the transesterification reaction of triacylglycerols present in sunflower oil with methanol. A kinetic modeling study under the specific conditions of 2 wt% catalyst dosage, 1:10 oil/methanol molar ratio, for 0–120 min at 35–65 ℃ was conducted, and liquid–liquid extraction with water/butanol was evaluated as a process to recover the IL. A 95.0% ester yield content was achieved in this work for a short reaction time (30 min). Furthermore, the results of the kinetic study demonstrated that a first-order model was the best fit for the reaction with a rate constant (k) estimated as 0.1182 min 1 and activation energy (Ea) of 13.64 kJ/mol. For the tested conditions, the complete recovery of the IL using liquid–liquid extraction did not occur since it is noted the presence of ChOH in both phases.
- Evaluation of Alkaline ionic liquids for catalysis of biodiesel from cooking oilPublication . Lima, Ana Carolina Coelho; Queiroz, Ana; Ribeiro, António E.; Brito, Paulo; Gomes, Maria Carolina SérgiBiodiesel production is performed in the industry by alkaline transesterification of oils with a low amount of free fatty acids. Aiming to minimize its production costs, low quality, or waste oils have been investigated as an alternative source of triacylglycerols. In order to reduce the disposal of conventional catalysts used industrially, ionic liquids (ILs) have been studied to be applied as catalysts in transesterification, since they can be recovered and reused in next reaction cycles. The main objective of this work was to investigate the application of alkaline type ionic liquids in the catalysis of transesterification reactions of mixtures of triacylglycerols. In the present work, the ionic liquid bis-(3-methyl-1-imidazole)-ethylene dihydroxide (IMC2OH) synthesis was carried out. The use of the IL choline hydroxide (ChOH) as a catalyst was evaluated in the production of biodiesel through a kinetic modelling study under the specific conditions of 2 wt.% catalyst dosage, 1:10 oil/methanol molar ratio, for the periods of 0, 10, 20, 30, 45, 60, 120, 240, 360, and 480 minutes at 65 ℃. A possible way to recover this IL from liquid-liquid extraction with water/butanol and water/ethyl acetate has been evaluated. Due to some challenges occurred in IMC2OH synthesis, the conversion obtained in the second step of synthesis was lower than expected. Transesterification with choline hydroxide presented 85.21% of conversion in FAME content in 30 minutes of reaction, and the results of the kinetic study which was carried out demonstrated that the second-order model was the best fit for the reaction with a rate constant (k) estimated as 0.2930 L.mol-1.min-1. From the recovery of the IL, it was possible to conclude that although there was some separation of it from the glycerol by the extraction with butanol and water, an amount of ChOH remained in glycerol phase. In conclusion, ChOH revealed an excellent capacity for fast transesterification. Thus, based on a more detailed study of the optimal reaction parameters for ChOH and subsequent application of the recovered amount of this ionic liquid in new reaction cycles, there is a strong indication that its reuse as a catalyst is technically feasible for the conversion of triacylglycerols, which enables its possible industrial application.
- Síntese e avaliação de um líquido iónico alcalino na produção de biodieselPublication . Lima, Ana Carolina Coelho; Queiroz, Ana; Ribeiro, António E.; Gomes, Maria Carolina Sérgi; Brito, PauloBiodiesel is an attractive biofuel to overcome energy depletion from fossil fuels since it has similar properties to diesel and exhibit biodegradability, non-toxicity and low carbon content. Currently, the production of biodiesel is done by the conversion of edible oils containing triglycerides through a transesterification reaction. However, concerns related to first-generation biodiesel such as the high cost of these oils, the competition with food markets, and the possibility of soil degradation made the use of waste oils in biodiesel production a possibility. These oils are considered a promising alternative in biodiesel synthesis, due to their low cost, high availability and arise as possible alternatives to overcome the disadvantages of the traditional production processes. Therefore, this study focuses on the research of producing biodiesel in a more sustainable way, i.e., the production of biodiesel from waste oils and the application of an ionic liquid (IL) as catalyst. The interest in IL is related to their near-zero vapor pressure and other properties such as their low volatility, high thermal and chemical stability, solvent properties and the possibility to be recovered and reused in new reaction cycles. In this research, the bis-(3-methyl-1-imidazolium)-ethylene dihydroxide (IMC2OH) IL was synthesized and characterized, showing good catalytic character for the transesterification of sunflower oil samples. Thus, the IL will be applied in the transesterification of waste cooking oils, and the effects of different reaction conditions on the preparation of biodiesel, such as reaction time, reaction temperature, alcohol/oil molar ratio and catalyst dosage, will be assessed.
- Study of the performance of alkaline ionic liquids for the catalysis of biodiesel production from waste cooking oilPublication . Lima, Ana Carolina Coelho; Gomes, Maria Carolina Sérgi; Brito, Paulo; Queiroz, Ana; Ribeiro, António E.Fossil fuels are a primary energy resource that play a critical role in our daily activities. Currently, the provision of energy relies primarily on fossil fuels such as coal, petroleum and natural gas. Although the fossil-based fuels are satisfying the energy requirements of the world, the depletion of fossil energy reserves, the high demand for fossil fuels and the dependence on it have led researchers to search for sustainable and environmental-friendly energy sources. In this scenario, biodiesel is a sustainable alternative compared to diesel, due to its biodegradability, non-toxicity and low carbon content. Biodiesel can be a blended component in transportation fuels, as it demonstrates similar characteristics to petroleum diesel and has lower greenhouse gas (GHG) emissions. Moreover, there are some concerns related to first-generation biodiesel (derived from food crops), such as the high cost of these oils, which accounts for about 70% of the total value of biodiesel production, as well as the competition with food markets, and the possibility of promoting soil degradation through the uncontrolled stimulation of energy crops. Hence, second-generation biodiesel production has a considerable potential to reduce waste residues and GHG emissions by replacing fossil fuels. Waste cooking oils (WCO) are considered a promising alternative in biodiesel synthesis, due to their low cost, high availability and arise as possible alternatives to overcome the disadvantages of the traditional production processes. Therefore, this study focuses on the research of producing biodiesel in a more sustainable way, namely the production of biodiesel from waste oils and the application of an ionic liquid as catalyst. Ionic liquids (ILs) are organic salts composed of cations and anions that can be used in biodiesel catalysis due to their attractive properties, such as good chemical stability, low vapor pressure, ability to be dissolved in a large range of inorganic and organic compounds and simple recovery process. In this work, alkaline ILs, bis-(3-methyl-1-imidazolium-)-ethylene dihydroxide and choline hydroxide, were selected for the study of their performance for the catalysis of biodiesel production from WCO samples. The ILs were synthesized, characterised and used for the production of biodiesel batches. Operational parameters such as reaction time, reaction temperature, alcohol/oil molar ratio and catalyst dosage, will be optimized. IL recyclability will be assessed, and kinetic studies will be carried out to determine the activation energy of the transesterification reaction catalysed by the referred ILs.
- Study of the performance of alkaline ionic liquids for the catalysis of biodiesel production from waste cooking oilPublication . Lima, Ana Carolina Coelho; Gomes, Maria Carolina Sérgi; Brito, Paulo; Queiroz, Ana; Ribeiro, António E.Fossil fuels are a primary energy resource that play a critical role in our daily activities. Currently, the provision of energy relies primarily on fossil fuels such as coal, petroleum and natural gas. Although the fossil-based fuels are satisfying the energy requirements of the world, the depletion of fossil energy reserves, the high demand for fossil fuels and the dependence on it have led researchers to search for sustainable and environmental-friendly energy sources. In this scenario, biodiesel is a sustainable alternative compared to diesel, due to its biodegradability, non-toxicity and low carbon content. Biodiesel can be a blended component in transportation fuels, as it demonstrates similar characteristics to petroleum diesel and has lower greenhouse gas (GHG) emissions. Moreover, there are some concerns related to first-generation biodiesel (derived from food crops), such as the high cost of these oils, which accounts for about 70% of the total value of biodiesel production, as well as the competition with food markets, and the possibility of promoting soil degradation through the uncontrolled stimulation of energy crops. Hence, second-generation biodiesel production has a considerable potential to reduce waste residues and GHG emissions by replacing fossil fuels. Waste cooking oils (WCO) are considered a promising alternative in biodiesel synthesis, due to their low cost, high availability and arise as possible alternatives to overcome the disadvantages of the traditional production processes.