The Experts below are selected from a list of 6156 Experts worldwide ranked by ideXlab platform
Rafael C Rodrigues - One of the best experts on this subject based on the ideXlab platform.
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the combined use of ultrasound and molecular sieves improves the synthesis of ethyl butyrate catalyzed by immobilized thermomyces lanuginosus lipase
Ultrasonics Sonochemistry, 2015Co-Authors: Natalia Paludo, Roberto Fernandezlafuente, Marco Antonio Zachia Ayub, Joana S Alves, Cintia Altmann, Rafael C RodriguesAbstract:Abstract In this work, the combined use of ultrasound energy and molecular sieves was investigated for the synthesis of ethyl butyrate, ester with mango and banana notes, catalyzed by the immobilized lipase from Thermomyces lanuginosus (Lipozyme TL-IM). Initially, the best concentrations of biocatalysts (35%) and butyric acid (0.7 M) were tested using ultrasound as an alternative to Mechanical Agitation. The amount of acid in the reaction could be increased by 2-fold when compared to previous works where Mechanical Agitation was used. In the next step, substrate molar ratio and reaction temperature were optimized and the best conditions were at their lowest levels: 1:1 (acid:alcohol), and 30 °C, reaching 61% of conversion in 6 h. Molecular sieves (3 A) were added to optimized reaction medium in order to remove the formed water and improve the maximum yield. The reaction yield increased 1.5 times, reaching 90% of conversion in 6 h, when 60 mg of molecular sieves per mmol of butyric acid was used. Finally, the reuse of Lipozyme TL-IM for the ultrasound-assisted synthesis of ethyl butyrate was verified for 10 batches, without any appreciable loss of activity, whereas in systems using Mechanical Agitation, the biocatalyst was completely inactivated after 5 batches. These results suggest that the combined use of ultrasound and molecular sieves greatly improve esterification reactions by stabilizing the enzyme and increasing yields.
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ultrasound assisted butyl acetate synthesis catalyzed by novozym 435 enhanced activity and operational stability
Ultrasonics Sonochemistry, 2013Co-Authors: Andrea B Martins, Roberto Fernandezlafuente, Marco Antonio Zachia Ayub, Mirela F Schein, John L R Friedrich, Rafael C RodriguesAbstract:Abstract The influence of low-frequency ultrasound (40 kHz) in the esterification reaction between acetic acid and butanol for flavor ester synthesis catalyzed by the commercial immobilized lipase B from Candida antarctica (Novozym 435) was evaluated. A central composite design and the response surface methodology were used to analyze the effects of the reaction parameters (temperature, substrate molar ratio, enzyme content and added water) and their response (yields of conversion in 2.5 h of reaction). The reaction was carried out using n -hexane as solvent. The optimal conditions for ultrasound-assisted butyl acetate synthesis were found to be: temperature of 46 °C; substrate molar ratio of 3.6:1 butanol:acetic acid; enzyme content of 7%; added water of 0.25%, conditions that are slightly different from those found using Mechanical mixing. Over 94% of conversion was obtained in 2.5 h under these conditions. The optimal acid concentration for the reaction was determined to be 2.0 M, compared to 0.3 M without ultrasound treatment. Enzyme productivity was significantly improved to around 7.5-fold for each batch when comparing ultrasound and standard Mechanical Agitation. The biocatalyst could be directly reused for 14 reactions cycles keeping around 70% of its original activity, while activity was virtually zeroed in the third cycle using the standard mixing system. Thus, compared to the traditional Mechanical Agitation, ultrasound technology not only improves the process productivity, but also enhances enzyme recycling and stability in the presence of acetic acid, being a powerful tool to improve biocatalyst performance in this type of reaction.
Alessandro Paglianti - One of the best experts on this subject based on the ideXlab platform.
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optimization of Mechanical Agitation and evaluation of the mass transfer resistance in the oil transesterification reaction for biodiesel production
Industrial & Engineering Chemistry Research, 2009Co-Authors: Dario Frascari, Michele Zuccaro, Alessandro Paglianti, Davide PinelliAbstract:The KOH-catalyzed transesterification of sunflower oil with methanol was studied in batch conditions in a 22 L stirred reactor in order to (i) develop criteria for the energetic optimization of Mechanical Agitation in the biodiesel synthesis reaction; (ii) obtain preliminary information on the decantation of the reaction products; (iii) evaluate the influence of the mass-transfer resistance under different mixing conditions. Different combinations of radial, axial, and pitched-blade impellers were tested. For each combination an optimal rotational speed was identified, characterized on the one hand by a drastic reduction of the specific mixing energy, and on the other by a 20−30% increase of reaction time. An evaluation of the reaction and mass-transfer characteristic times showed that the optimized tests are characterized by a not negligible mass-transfer resistance. The complete halt of the Agitation after a 1−2 min mixing time led to a further decrease of mixing energy, without any increase of reaction...
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a pilot scale study of alkali catalyzed sunflower oil transesterification with static mixing and with Mechanical Agitation
Energy & Fuels, 2008Co-Authors: Dario Frascari, Michele Zuccaro, Davide Pinelli, Alessandro PagliantiAbstract:The utilization of Sulzer 15 mm SMV static mixers (SM) for the KOH-catalyzed transesterification of sunflower oil was studied by means of batch tests conducted in an experimental ring equipped with a 22 L reactor with a 6:1 methanol:oil molar ratio. The effect of SM number and superficial velocity was investigated. The results were compared to those of analogous tests performed with only Mechanical Agitation, at different rotational speeds and catalyst concentrations. The tests conducted with one single SM at a 1.3 m/s superficial velocity (Re = 1490) resulted in a profile of sunflower oil conversion versus time equivalent to that obtained in the best-performing test with Mechanical Agitation, indicating the attainment of a reaction run not affected by mass transfer limitations. In an evaluation of the energy requirement for the attainment of the alcohol/oil dispersion, the SM tests performed better than those with Mechanical Agitation (17 vs 35 J/kgbiodiesel, in the reaction conditions without mass trans...
Roberto Fernandezlafuente - One of the best experts on this subject based on the ideXlab platform.
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the combined use of ultrasound and molecular sieves improves the synthesis of ethyl butyrate catalyzed by immobilized thermomyces lanuginosus lipase
Ultrasonics Sonochemistry, 2015Co-Authors: Natalia Paludo, Roberto Fernandezlafuente, Marco Antonio Zachia Ayub, Joana S Alves, Cintia Altmann, Rafael C RodriguesAbstract:Abstract In this work, the combined use of ultrasound energy and molecular sieves was investigated for the synthesis of ethyl butyrate, ester with mango and banana notes, catalyzed by the immobilized lipase from Thermomyces lanuginosus (Lipozyme TL-IM). Initially, the best concentrations of biocatalysts (35%) and butyric acid (0.7 M) were tested using ultrasound as an alternative to Mechanical Agitation. The amount of acid in the reaction could be increased by 2-fold when compared to previous works where Mechanical Agitation was used. In the next step, substrate molar ratio and reaction temperature were optimized and the best conditions were at their lowest levels: 1:1 (acid:alcohol), and 30 °C, reaching 61% of conversion in 6 h. Molecular sieves (3 A) were added to optimized reaction medium in order to remove the formed water and improve the maximum yield. The reaction yield increased 1.5 times, reaching 90% of conversion in 6 h, when 60 mg of molecular sieves per mmol of butyric acid was used. Finally, the reuse of Lipozyme TL-IM for the ultrasound-assisted synthesis of ethyl butyrate was verified for 10 batches, without any appreciable loss of activity, whereas in systems using Mechanical Agitation, the biocatalyst was completely inactivated after 5 batches. These results suggest that the combined use of ultrasound and molecular sieves greatly improve esterification reactions by stabilizing the enzyme and increasing yields.
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ultrasound assisted butyl acetate synthesis catalyzed by novozym 435 enhanced activity and operational stability
Ultrasonics Sonochemistry, 2013Co-Authors: Andrea B Martins, Roberto Fernandezlafuente, Marco Antonio Zachia Ayub, Mirela F Schein, John L R Friedrich, Rafael C RodriguesAbstract:Abstract The influence of low-frequency ultrasound (40 kHz) in the esterification reaction between acetic acid and butanol for flavor ester synthesis catalyzed by the commercial immobilized lipase B from Candida antarctica (Novozym 435) was evaluated. A central composite design and the response surface methodology were used to analyze the effects of the reaction parameters (temperature, substrate molar ratio, enzyme content and added water) and their response (yields of conversion in 2.5 h of reaction). The reaction was carried out using n -hexane as solvent. The optimal conditions for ultrasound-assisted butyl acetate synthesis were found to be: temperature of 46 °C; substrate molar ratio of 3.6:1 butanol:acetic acid; enzyme content of 7%; added water of 0.25%, conditions that are slightly different from those found using Mechanical mixing. Over 94% of conversion was obtained in 2.5 h under these conditions. The optimal acid concentration for the reaction was determined to be 2.0 M, compared to 0.3 M without ultrasound treatment. Enzyme productivity was significantly improved to around 7.5-fold for each batch when comparing ultrasound and standard Mechanical Agitation. The biocatalyst could be directly reused for 14 reactions cycles keeping around 70% of its original activity, while activity was virtually zeroed in the third cycle using the standard mixing system. Thus, compared to the traditional Mechanical Agitation, ultrasound technology not only improves the process productivity, but also enhances enzyme recycling and stability in the presence of acetic acid, being a powerful tool to improve biocatalyst performance in this type of reaction.
Marco Antonio Zachia Ayub - One of the best experts on this subject based on the ideXlab platform.
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the combined use of ultrasound and molecular sieves improves the synthesis of ethyl butyrate catalyzed by immobilized thermomyces lanuginosus lipase
Ultrasonics Sonochemistry, 2015Co-Authors: Natalia Paludo, Roberto Fernandezlafuente, Marco Antonio Zachia Ayub, Joana S Alves, Cintia Altmann, Rafael C RodriguesAbstract:Abstract In this work, the combined use of ultrasound energy and molecular sieves was investigated for the synthesis of ethyl butyrate, ester with mango and banana notes, catalyzed by the immobilized lipase from Thermomyces lanuginosus (Lipozyme TL-IM). Initially, the best concentrations of biocatalysts (35%) and butyric acid (0.7 M) were tested using ultrasound as an alternative to Mechanical Agitation. The amount of acid in the reaction could be increased by 2-fold when compared to previous works where Mechanical Agitation was used. In the next step, substrate molar ratio and reaction temperature were optimized and the best conditions were at their lowest levels: 1:1 (acid:alcohol), and 30 °C, reaching 61% of conversion in 6 h. Molecular sieves (3 A) were added to optimized reaction medium in order to remove the formed water and improve the maximum yield. The reaction yield increased 1.5 times, reaching 90% of conversion in 6 h, when 60 mg of molecular sieves per mmol of butyric acid was used. Finally, the reuse of Lipozyme TL-IM for the ultrasound-assisted synthesis of ethyl butyrate was verified for 10 batches, without any appreciable loss of activity, whereas in systems using Mechanical Agitation, the biocatalyst was completely inactivated after 5 batches. These results suggest that the combined use of ultrasound and molecular sieves greatly improve esterification reactions by stabilizing the enzyme and increasing yields.
-
ultrasound assisted butyl acetate synthesis catalyzed by novozym 435 enhanced activity and operational stability
Ultrasonics Sonochemistry, 2013Co-Authors: Andrea B Martins, Roberto Fernandezlafuente, Marco Antonio Zachia Ayub, Mirela F Schein, John L R Friedrich, Rafael C RodriguesAbstract:Abstract The influence of low-frequency ultrasound (40 kHz) in the esterification reaction between acetic acid and butanol for flavor ester synthesis catalyzed by the commercial immobilized lipase B from Candida antarctica (Novozym 435) was evaluated. A central composite design and the response surface methodology were used to analyze the effects of the reaction parameters (temperature, substrate molar ratio, enzyme content and added water) and their response (yields of conversion in 2.5 h of reaction). The reaction was carried out using n -hexane as solvent. The optimal conditions for ultrasound-assisted butyl acetate synthesis were found to be: temperature of 46 °C; substrate molar ratio of 3.6:1 butanol:acetic acid; enzyme content of 7%; added water of 0.25%, conditions that are slightly different from those found using Mechanical mixing. Over 94% of conversion was obtained in 2.5 h under these conditions. The optimal acid concentration for the reaction was determined to be 2.0 M, compared to 0.3 M without ultrasound treatment. Enzyme productivity was significantly improved to around 7.5-fold for each batch when comparing ultrasound and standard Mechanical Agitation. The biocatalyst could be directly reused for 14 reactions cycles keeping around 70% of its original activity, while activity was virtually zeroed in the third cycle using the standard mixing system. Thus, compared to the traditional Mechanical Agitation, ultrasound technology not only improves the process productivity, but also enhances enzyme recycling and stability in the presence of acetic acid, being a powerful tool to improve biocatalyst performance in this type of reaction.
Davide Pinelli - One of the best experts on this subject based on the ideXlab platform.
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optimization of Mechanical Agitation and evaluation of the mass transfer resistance in the oil transesterification reaction for biodiesel production
Industrial & Engineering Chemistry Research, 2009Co-Authors: Dario Frascari, Michele Zuccaro, Alessandro Paglianti, Davide PinelliAbstract:The KOH-catalyzed transesterification of sunflower oil with methanol was studied in batch conditions in a 22 L stirred reactor in order to (i) develop criteria for the energetic optimization of Mechanical Agitation in the biodiesel synthesis reaction; (ii) obtain preliminary information on the decantation of the reaction products; (iii) evaluate the influence of the mass-transfer resistance under different mixing conditions. Different combinations of radial, axial, and pitched-blade impellers were tested. For each combination an optimal rotational speed was identified, characterized on the one hand by a drastic reduction of the specific mixing energy, and on the other by a 20−30% increase of reaction time. An evaluation of the reaction and mass-transfer characteristic times showed that the optimized tests are characterized by a not negligible mass-transfer resistance. The complete halt of the Agitation after a 1−2 min mixing time led to a further decrease of mixing energy, without any increase of reaction...
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a pilot scale study of alkali catalyzed sunflower oil transesterification with static mixing and with Mechanical Agitation
Energy & Fuels, 2008Co-Authors: Dario Frascari, Michele Zuccaro, Davide Pinelli, Alessandro PagliantiAbstract:The utilization of Sulzer 15 mm SMV static mixers (SM) for the KOH-catalyzed transesterification of sunflower oil was studied by means of batch tests conducted in an experimental ring equipped with a 22 L reactor with a 6:1 methanol:oil molar ratio. The effect of SM number and superficial velocity was investigated. The results were compared to those of analogous tests performed with only Mechanical Agitation, at different rotational speeds and catalyst concentrations. The tests conducted with one single SM at a 1.3 m/s superficial velocity (Re = 1490) resulted in a profile of sunflower oil conversion versus time equivalent to that obtained in the best-performing test with Mechanical Agitation, indicating the attainment of a reaction run not affected by mass transfer limitations. In an evaluation of the energy requirement for the attainment of the alcohol/oil dispersion, the SM tests performed better than those with Mechanical Agitation (17 vs 35 J/kgbiodiesel, in the reaction conditions without mass trans...