The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Mingguang Zhang - One of the best experts on this subject based on the ideXlab platform.
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Thermal runaway and shortstopping of Esterification in batch stirred reactors
Process Safety and Environmental Protection, 2017Co-Authors: Mingguang Zhang, Lei Ni, Juncheng Jiang, Wenxing ZhangAbstract:Abstract This research deals with the thermal runaway and shortstopping of Esterification process in batch stirred reactors. A series of experiments were carried out with RC1e, and an autocatalytic kinetic model of Esterification process was established. The divergence criterion (DIV) which describes the trace of Jacobian matrix of temperature and reactant conversion was used to identify the thermal runaway boundary of Esterification. Computational fluid dynamics (CFD) simulation was employed to illustrate the temperature distribution inside the reactor. The cooling temperature and agitation speed significantly affect the Esterification runaway. CFD simulation of shortstopping runaway in Esterification process with cooling diluent injection was established to study the effect of addition location and quantity of the cold diluent on shortstopping performance.
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thermal runaway risk of semibatch processes Esterification reaction with autocatalytic behavior
Industrial & Engineering Chemistry Research, 2017Co-Authors: Lei Ni, Ahmed Mebarki, S. Mudi Mannan, Juncheng Jiang, Mingguang ZhangAbstract:The present paper deals with thermal runaway risk of Esterification reaction in semibatch reactor. It identifies thermal runaway conditions for the Esterification of 2-butanol (2B) and propionic anhydride (PA) with sulfuric acid (SA). The autocatalytic kinetic model of Esterification of 2B and PA with SA was obtained by the experiments. A new boundary diagram was proposed for the autocatalytic parallel reactions. Then, the combined boundary diagram considering the target temperature and maximum allowable temperature was used to define the critical conditions for the thermal runaway. The conditional probability of thermal runaway for Esterification of 2B and PA with SA was calculated by Monte Carlo simulations.
Lei Ni - One of the best experts on this subject based on the ideXlab platform.
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Thermal runaway and shortstopping of Esterification in batch stirred reactors
Process Safety and Environmental Protection, 2017Co-Authors: Mingguang Zhang, Lei Ni, Juncheng Jiang, Wenxing ZhangAbstract:Abstract This research deals with the thermal runaway and shortstopping of Esterification process in batch stirred reactors. A series of experiments were carried out with RC1e, and an autocatalytic kinetic model of Esterification process was established. The divergence criterion (DIV) which describes the trace of Jacobian matrix of temperature and reactant conversion was used to identify the thermal runaway boundary of Esterification. Computational fluid dynamics (CFD) simulation was employed to illustrate the temperature distribution inside the reactor. The cooling temperature and agitation speed significantly affect the Esterification runaway. CFD simulation of shortstopping runaway in Esterification process with cooling diluent injection was established to study the effect of addition location and quantity of the cold diluent on shortstopping performance.
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thermal runaway risk of semibatch processes Esterification reaction with autocatalytic behavior
Industrial & Engineering Chemistry Research, 2017Co-Authors: Lei Ni, Ahmed Mebarki, S. Mudi Mannan, Juncheng Jiang, Mingguang ZhangAbstract:The present paper deals with thermal runaway risk of Esterification reaction in semibatch reactor. It identifies thermal runaway conditions for the Esterification of 2-butanol (2B) and propionic anhydride (PA) with sulfuric acid (SA). The autocatalytic kinetic model of Esterification of 2B and PA with SA was obtained by the experiments. A new boundary diagram was proposed for the autocatalytic parallel reactions. Then, the combined boundary diagram considering the target temperature and maximum allowable temperature was used to define the critical conditions for the thermal runaway. The conditional probability of thermal runaway for Esterification of 2B and PA with SA was calculated by Monte Carlo simulations.
Pérez Camino, María Del Carmen - One of the best experts on this subject based on the ideXlab platform.
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Valorization of a high-acidity residual oil generated in the waste cooking oils recycling industries
'Editorial CSIC', 2020Co-Authors: Álvarez-mateos P., García-martín J.f., Guerrero-vacas F.j., Naranjo-calderón C., Barrios-sánchez C.c., Pérez Camino, María Del CarmenAbstract:A sludge fraction is obtained from the industries which recycle cooking oil and this sludge contains a large amount of oil with an extremely high acidity (> 60%). In this work, we propose a scheme for methyl ester production from this residual oil consisting of the Esterification of the free fatty acids followed by the transEsterification of the remaining triglycerides. Esterifications were carried out with different methanol:oil molar ratios, and various catalysts in different weight ratios. The results revealed that homogeneous catalysts produced higher yields than heterogeneous ones in the Esterification reaction. With the aim of improving the process, a previous triglyceride hydrolysis was assayed using lipases from Candida rugosa. Finally, the 3-stage process was performed under the most favorable conditions for each stage obtaining 84% wt. fatty acid methyl esters, which shows the potential of this residual oil as a source of biodiesel.This work was supported by the European Union Funds under grant LIFE 13-Bioseville ENV/1113. The authors are grateful to Grupo BIOSEL for supplying the residual oil
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Valorización de un aceite residual de alta acidez generado en las industrias de reciclaje de aceites de desecho de cocinas
Consejo Superior de Investigaciones Científicas CSIC: Instituto de la Grasa, 2019Co-Authors: Álvarez-mateos, María Paloma, García-martín, Juan Francisco, Guerrero-vacas, Francisco José, Naranjo-calderón Cristina, Barrios-sánchez, Carmen C., Pérez Camino, María Del CarmenAbstract:A sludge fraction is obtained from the industries which recycle cooking oil and this sludge con-tains a large amount of oil with an extremely high acidity (> 60%). In this work, we propose a scheme for methyl ester production from this residual oil consisting of the Esterification of the free fatty acids followed by the trans-Esterification of the remaining triglycerides. Esterifications were carried out with different methanol:oil molar ratios, and various catalysts in different weight ratios. The results revealed that homogeneous catalysts produced higher yields than heterogeneous ones in the Esterification reaction. With the aim of improving the process, a previous triglyceride hydrolysis was assayed using lipases from Candida rugosa. Finally, the 3-stage process was performed under the most favorable conditions for each stage obtaining 84% wt. fatty acid methyl esters, which shows the potential of this residual oil as a source of biodiesel.En las industrias de recogida y reciclado de aceites de fritura usados se obtiene una fracción de lodos que contiene un gran porcentaje de aceite con un extremadamente alto índice de acidez (> 60%). En este trabajo proponemos un esquema de producción de ésteres metílicos basado en la esterificación de los ácidos grasos libres seguida de la transesterificación de los triglicéridos remanentes. Las esterificaciones se llevaron a cabo usando diferentes relaciones molares metanol: aceite y diversos catalizadores en diferentes concentraciones en peso. Los resultados ilustraron que los catalizadores homogéneos alcanzaron mayores rendimientos en la esterificación que los catalizadores heterogéneos. Para mejorar el proceso, se probó una hidrólisis previa con lipasas de Candida rugosa. Finalmente, se llevó a cabo el proceso con las 3 etapas, en las condiciones más favorables de cada una de ellas, obteniendo un 84% en peso de ésteres metílicos, lo que muestra el potencial de este aceite residual como fuente de biodiésel.European Union Funds grant LIFE 13-Bioseville ENV/111
William E. Connor - One of the best experts on this subject based on the ideXlab platform.
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The effects of sterol structure upon sterol Esterification.
Atherosclerosis, 2009Co-Authors: Robert D. Steiner, Louise S. Merkens, Anuradha S. Pappu, William E. ConnorAbstract:Cholesterol is esterified in mammals by two enzymes: LCAT (lecithin cholesterol acyltransferase) in plasma and ACAT1 and ACAT2 (acyl-CoA cholesterol acyltransferases) in the tissues. We hypothesized that the sterol structure may have significant effects on the outcome of Esterification by these enzymes. To test this hypothesis, we analyzed sterol esters in plasma and tissues in patients having non-cholesterol sterols (sitosterolemia and Smith-Lemli-Opitz syndrome). The Esterification of a given sterol was defined as the sterol ester percentage of total sterols. The Esterification of cholesterol in plasma by LCAT was 67 percent and in tissues by ACAT was 64 percent. Esterification of nine sterols, (cholesterol, cholestanol, campesterol, stigmasterol, sitosterol, campestanol, sitostanol, 7-dehydrocholesterol and 8-dehydrocholesterol) was examined.(The relative Esterification (cholesterol being 1.0) of these sterols by the plasma LCAT was 1.00, 0.95, 0.89, 0.40, 0.85, 0.82 and 0.80, 0.69 and 0.82 respectively. The Esterification by the tissue ACAT was 1.00, 1.29, 0.75, 0.49, 0.45, 1.21 and 0.74 respectively. The predominant fatty acid of the sterol esters was linoleic acid for LCAT and oleic acid for ACAT. We compared the Esterification of two sterols differing by only one functional group (a chemical group attached to sterol nucleus) and were able to quantify the effects of individual functional groups on sterol Esterification. The saturation of the A ring of cholesterol increased ester formation by ACAT by 29 percent and decreased the Esterification by LCAT by 5.9 percent. Esterification by ACAT and LCAT was reduced respectively by 25 percent and 11 percent by the presence of an additional methyl group on the side chain of cholesterol at the C-24 position. This data supports our hypothesis that the structure of the sterol substrate has a significant effect on its Esterification by ACAT or LCAT.
Naoki Azuma - One of the best experts on this subject based on the ideXlab platform.
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continuous and consecutive conversion of free fatty acid in rice bran oil to triacylglycerol using immobilized lipase
Applied Microbiology and Biotechnology, 1994Co-Authors: Yoshitsugu Kosugi, Naoki AzumaAbstract:Free fatty acid (FFA), monoacylglycerol (MG) and diacylglycerol (DG) in high-FFA rice bran oil were continuously converted with glycerol (G) to form triacylglycerol (TG), using lipase fromRhizomucor miehei immobilized on anion-exchange resin. The reaction was continued for more than 1 month by a reactor with two circulation loops, each being connected to a fixed-bed reactor and a dehydrator. The reaction of 2 FFA + G → DG + 2H2O appeared to occur until the glycerol was exhausted; the reaction of FFA + DG → TG + H2O then followed. The consecutive esterificaion continued in the presence of 2–8 ppm water and the TG content reached 74%–88%. The industrial feasibility of this process was assessed from the standpoints of enzyme cost and value added by Esterification.
