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Shan Jiang,Zuoxiang Zeng,Weilan Xue,Wei Zhang,Zhiyuan Zhou 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.9
This study explored the direct esterification of palmitic acid and ethanol using a deep eutectic solvent (DES) as catalyst to produce biodiesel. Three novel deep eutectic solvents (DTAC-PTSA, DTAC-2PTSA, DTAC3PTSA) were successfully prepared by mixing dodecyl trimethyl ammonium chloride (DTAC) and p-toluenesulfonic acid monohydrate (PTSA) in a molar ratio of 1: z (z=1, 2, 3). After testing, DTAC-3PTSA was found to have the best catalytic performance among the three types of DESs and was therefore selected as the catalyst for subsequent experiments. The effects of agitation speed, ethanol to palmitic acid molar ratio (), temperature and catalyst dosage were studied by investigating the change of palmitic acid conversion rate with time under different conditions, respectively. Then, the pseudo-homogeneous (PH) model was utilized to describe the kinetic behavior of this reaction between 328.15-348.15 K and it was found to work well for the experimental data obtained. Moreover, the catalytic performance of DTAC-3PTSA was detected to have no significant change in the cycle test. Therefore, DTAC-3PTSA can be considered as a substitute for traditional catalysts to produce biodiesel and the kinetic data obtained here can be used for further up-scaling study
Kinetics of polyvinyl butyral hydrolysis in ethanol/water solutions
Wenwen Luan,Chunyu Wang,Zuoxiang Zeng,Weilan Xue,Xuelian He,Yu Bai 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.9
The hydrolysis kinetics of polyvinyl butyral (PVB) was studied in ethanol/water mixed solvents in the temperature range of 339.15-355.15 K, and a three-step hypothesis was proposed to describe the hydrolysis process. The influences of stirring speed, ethanol content and temperature on the hydrolysis of PVB were investigated, and an induction period (IP) phenomenon was found in the process of PVB hydrolysis. The ethanol content in the mixed solvents has a great influence on IP, which is due to the formation of the two kinds of water-ethanol clusters in the system. Temperature influences the IP by changing the catalytic activity of hydroxylamine hydrochloride (HH) on the hydrolysis of PVB. The shrinking core models with three controlling steps were used to fit the kinetic data, and the results indicate that the model controlled by chemical reaction is suitable to describe the kinetic behavior of PVB hydrolysis.
Liwei Chen,Jumei Xu,Weilan Xue,Zuoxiang Zeng 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.1
An eight-step mechanism of esterification reaction between adipic acid (AA) and ethylene glycol (EG) catalyzed by tetrabutyl titanate [Ti(OBu)4] was studied in detail. The kinetic data for the esterification reaction between AA and EG catalyzed by tetrabutyl titanate [Ti(OBu)4] were measured in the temperature range of 403 K-433 K. A second- order kinetic model was established, and the model parameters were obtained through an optimization procedure by minimizing the value differences between the simulated component concentrations in the reaction system with the experimental ones. The results demonstrate that the model is suitable for the esterification reaction between AA and EG catalyzed by tetrabutyl titanate [Ti(OBu)4]. Furthermore, the esterification reaction rate increases with the increase of reaction temperature, concentration of catalyst and the initial reactant ratio of EG to AA.
Zhijuan Huang,Chao Yu,Weilan Xue,Fucong Lin,Zuoxiang Zeng 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.1
The solubility of hexaquoiron(III)tris(p-toluenesulfonate) [Fe(OTs)3·6H2O] in (ethanol+water) mixtures with a mole fraction of 0-0.327 ethanol was measured from 291.15 to 333.15 K by using a synthetic method. The experimental results show that the solubility of Fe(OTs)3·6H2O increases with an increase in temperature and an enrichment in ethanol content. The solubility data were correlated by the modified Apelblat equation, the Redlich-Kister (CNIBS/R-K) model, and the hybrid model, and the results showed that the three models agree well with experimental data. The thermodynamic properties of the dissolution process, including enthalpy, entropy, and Gibbs energy were estimated from the experimental data by the modified van’t Hoff equation, indicating that the process of the dissolution of Fe(OTs)3·6H2O is endothermic and spontaneous.