TY  - JOUR
AU  - Kesić, Željka
AU  - Lukić, Ivana
AU  - Zdujić, Miodrag
AU  - Jovalekić, Čedomir
AU  - Liu, Hui
AU  - Skala, Dejan
PY  - 2015
UR  - http://dais.sanu.ac.rs/123456789/3542
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/2606
AB  - The goal of this study was to prepare a CaO·ZnO catalyst containing a small amount of K2CO3 and analyze its activity for biodiesel synthesis. The catalyst was prepared using the following procedure: CaO and ZnO (mole ratio of 1:2), water and K2CO3 (in various amounts) were mechanochemically treated and after milling heated at 700 °C in air atmosphere for obtaining mixed CaO·ZnO/xK2CO3 oxides (x = 0, 1, 2 and 4 mol of K2CO3 per 10 mol of CaO). All the samples were characterized by X-ray diffraction (XRD), inductively coupled plasma (ICP), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), infrared spectroscopy (FTIR), scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS), particle size laser diffraction (PSLD) distribution, solubility measurement of Ca, Zn and K ions in methanol as well as by determination of their alkalinity (Hammett Indicator method). Prepared CaO·ZnO/xK2CO3 composite powders were tested as catalysts for methanolysis of sunflower oil at 70 °C using mole ratio of sunflower oil to methanol of 1:10 and with 2 mass% of catalyst based on oil weight. The presence of K2CO3 in prepared samples was found to increase the activity of catalyst, and that such effect is caused by homogeneous-heterogeneous catalysis of biodiesel synthesis. © 2015, CI and CEQ. All Rights Reserved.
PB  - Belgrade: Association of the Chemical Engineers of Serbia
T2  - Chemical Industry and Chemical Engineering Quarterly
T1  - Mechanochemical synthesis of CaO·ZnO·K2CO3 catalyst: Characterization and activity for methanolysis of sunflower oil
VL  - 21
IS  - 1
SP  - 1
EP  - 12
DO  - 10.2298/CICEQ131026041K
ER  - 

@article{
author = "Kesić, Željka and Lukić, Ivana and Zdujić, Miodrag and Jovalekić, Čedomir and Liu, Hui and Skala, Dejan",
year = "2015",
abstract = "The goal of this study was to prepare a CaO·ZnO catalyst containing a small amount of K2CO3 and analyze its activity for biodiesel synthesis. The catalyst was prepared using the following procedure: CaO and ZnO (mole ratio of 1:2), water and K2CO3 (in various amounts) were mechanochemically treated and after milling heated at 700 °C in air atmosphere for obtaining mixed CaO·ZnO/xK2CO3 oxides (x = 0, 1, 2 and 4 mol of K2CO3 per 10 mol of CaO). All the samples were characterized by X-ray diffraction (XRD), inductively coupled plasma (ICP), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), infrared spectroscopy (FTIR), scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS), particle size laser diffraction (PSLD) distribution, solubility measurement of Ca, Zn and K ions in methanol as well as by determination of their alkalinity (Hammett Indicator method). Prepared CaO·ZnO/xK2CO3 composite powders were tested as catalysts for methanolysis of sunflower oil at 70 °C using mole ratio of sunflower oil to methanol of 1:10 and with 2 mass% of catalyst based on oil weight. The presence of K2CO3 in prepared samples was found to increase the activity of catalyst, and that such effect is caused by homogeneous-heterogeneous catalysis of biodiesel synthesis. © 2015, CI and CEQ. All Rights Reserved.",
publisher = "Belgrade: Association of the Chemical Engineers of Serbia",
journal = "Chemical Industry and Chemical Engineering Quarterly",
title = "Mechanochemical synthesis of CaO·ZnO·K2CO3 catalyst: Characterization and activity for methanolysis of sunflower oil",
volume = "21",
number = "1",
pages = "1-12",
doi = "10.2298/CICEQ131026041K"
}

Kesić, Ž., Lukić, I., Zdujić, M., Jovalekić, Č., Liu, H.,& Skala, D.. (2015). Mechanochemical synthesis of CaO·ZnO·K2CO3 catalyst: Characterization and activity for methanolysis of sunflower oil. in Chemical Industry and Chemical Engineering Quarterly
Belgrade: Association of the Chemical Engineers of Serbia., 21(1), 1-12.
https://doi.org/10.2298/CICEQ131026041K

Kesić Ž, Lukić I, Zdujić M, Jovalekić Č, Liu H, Skala D. Mechanochemical synthesis of CaO·ZnO·K2CO3 catalyst: Characterization and activity for methanolysis of sunflower oil. in Chemical Industry and Chemical Engineering Quarterly. 2015;21(1):1-12.
doi:10.2298/CICEQ131026041K .

Kesić, Željka, Lukić, Ivana, Zdujić, Miodrag, Jovalekić, Čedomir, Liu, Hui, Skala, Dejan, "Mechanochemical synthesis of CaO·ZnO·K2CO3 catalyst: Characterization and activity for methanolysis of sunflower oil" in Chemical Industry and Chemical Engineering Quarterly, 21, no. 1 (2015):1-12,
https://doi.org/10.2298/CICEQ131026041K . .

TY  - JOUR
AU  - Lukić, Ivana
AU  - Kesić, Željka
AU  - Maksimović, Svetolik
AU  - Zdujić, Miodrag
AU  - Krstić, Jugoslav
AU  - Skala, Dejan
PY  - 2014
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/1461
AB  - The kinetics of heterogeneous methanolysis of sunflower oil was studied at 60 °C using mechanochemically synthesized CaO·ZnO as catalyst. The influence of agitation speed, catalyst amount, and methanol-to-oil molar ratio on the rate of reaction was analyzed. The rate of the process depends on the two resistances - mass transfer of triglycerides to the catalyst surface and chemical reaction on the catalyst surface, which are defined as the values of the overall triglyceride volumetric mass transfer coefficient, kmt,TG, and the effective pseudo first-order reaction rate constant, k, respectively. These kinetic parameters actually determine the value of the apparent reaction rate constant, kapp, the time dependence of which is defined by the change of triglyceride (TG) conversion. A kinetic model is proposed and the model parameters are determined.
AB  - Kinetika heterogene metanolize suncokretovog ulja je ispitivana na 60 °C korišćenjem CaO·ZnO katalizatora koji je sintetizovan mehanohemijskim putem. Analiziran je uticaj intenziteta mešanja, mase korišćenog katalizatora u sintezi i različitog molskog odnosa metanola i ulja na brzinu metanolize. Brzina procesa metanolize zavisi od dva otpora - otpora prenosu mase triglicerida do površine katalizatora i otpora brzini hemijske reakcije na površini katalizatora. Oba otpora određuju vrednost ukupnog zapreminskog koeficijenta prenosa mase triglicerida, kmt,TG, odnosno efektivne vrednosti konstante brzine hemijske reakcije pseudo-prvog reda, k. Ovi kinetički parametri određuju vrednost prividne konstante brzine procesa metanolize, kapp, koja se menja sa vremenom u zavisnosti od ostvareneog stepena konverzije triglicerida (TG). Predložen je odgovarajući model kojim je moguće definisati brzinu metanolize i određeni su odgovarajući parametri ovog modela.
PB  - Belgrade : Association of the Chemical Engineers of Serbia
T2  - Chemical Industry and Chemical Engineering Quarterly
T1  - Kinetics of heterogeneous methanolysis of sunflower oil with CaO·ZnO catalyst: Influence of different hydrodynamic conditions
T1  - Kinetika heterogene metanolize suncokretovog ulja sa CaO·ZnO kao katalizatorom - uticaj različitih hidrodinamičkih uslova
VL  - 20
IS  - 3
SP  - 425
EP  - 439
DO  - 10.2298/CICEQ130514025L
ER  - 

@article{
author = "Lukić, Ivana and Kesić, Željka and Maksimović, Svetolik and Zdujić, Miodrag and Krstić, Jugoslav and Skala, Dejan",
year = "2014",
abstract = "The kinetics of heterogeneous methanolysis of sunflower oil was studied at 60 °C using mechanochemically synthesized CaO·ZnO as catalyst. The influence of agitation speed, catalyst amount, and methanol-to-oil molar ratio on the rate of reaction was analyzed. The rate of the process depends on the two resistances - mass transfer of triglycerides to the catalyst surface and chemical reaction on the catalyst surface, which are defined as the values of the overall triglyceride volumetric mass transfer coefficient, kmt,TG, and the effective pseudo first-order reaction rate constant, k, respectively. These kinetic parameters actually determine the value of the apparent reaction rate constant, kapp, the time dependence of which is defined by the change of triglyceride (TG) conversion. A kinetic model is proposed and the model parameters are determined., Kinetika heterogene metanolize suncokretovog ulja je ispitivana na 60 °C korišćenjem CaO·ZnO katalizatora koji je sintetizovan mehanohemijskim putem. Analiziran je uticaj intenziteta mešanja, mase korišćenog katalizatora u sintezi i različitog molskog odnosa metanola i ulja na brzinu metanolize. Brzina procesa metanolize zavisi od dva otpora - otpora prenosu mase triglicerida do površine katalizatora i otpora brzini hemijske reakcije na površini katalizatora. Oba otpora određuju vrednost ukupnog zapreminskog koeficijenta prenosa mase triglicerida, kmt,TG, odnosno efektivne vrednosti konstante brzine hemijske reakcije pseudo-prvog reda, k. Ovi kinetički parametri određuju vrednost prividne konstante brzine procesa metanolize, kapp, koja se menja sa vremenom u zavisnosti od ostvareneog stepena konverzije triglicerida (TG). Predložen je odgovarajući model kojim je moguće definisati brzinu metanolize i određeni su odgovarajući parametri ovog modela.",
publisher = "Belgrade : Association of the Chemical Engineers of Serbia",
journal = "Chemical Industry and Chemical Engineering Quarterly",
title = "Kinetics of heterogeneous methanolysis of sunflower oil with CaO·ZnO catalyst: Influence of different hydrodynamic conditions, Kinetika heterogene metanolize suncokretovog ulja sa CaO·ZnO kao katalizatorom - uticaj različitih hidrodinamičkih uslova",
volume = "20",
number = "3",
pages = "425-439",
doi = "10.2298/CICEQ130514025L"
}

Lukić, I., Kesić, Ž., Maksimović, S., Zdujić, M., Krstić, J.,& Skala, D.. (2014). Kinetics of heterogeneous methanolysis of sunflower oil with CaO·ZnO catalyst: Influence of different hydrodynamic conditions. in Chemical Industry and Chemical Engineering Quarterly
Belgrade : Association of the Chemical Engineers of Serbia., 20(3), 425-439.
https://doi.org/10.2298/CICEQ130514025L

Lukić I, Kesić Ž, Maksimović S, Zdujić M, Krstić J, Skala D. Kinetics of heterogeneous methanolysis of sunflower oil with CaO·ZnO catalyst: Influence of different hydrodynamic conditions. in Chemical Industry and Chemical Engineering Quarterly. 2014;20(3):425-439.
doi:10.2298/CICEQ130514025L .

Lukić, Ivana, Kesić, Željka, Maksimović, Svetolik, Zdujić, Miodrag, Krstić, Jugoslav, Skala, Dejan, "Kinetics of heterogeneous methanolysis of sunflower oil with CaO·ZnO catalyst: Influence of different hydrodynamic conditions" in Chemical Industry and Chemical Engineering Quarterly, 20, no. 3 (2014):425-439,
https://doi.org/10.2298/CICEQ130514025L . .

TY  - JOUR
AU  - Lukić, Ivana
AU  - Kesic, Zeljka
AU  - Maksimović, Svetolik
AU  - Zdujić, Miodrag
AU  - Liu, Hui
AU  - Krstić, Jugoslav
AU  - Skala, Dejan
PY  - 2013
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/1180
AB  - The kinetics of heterogeneous methanolysis of sunflower oil and used vegetable oil were studied at different temperatures, ranging from 60 to 96 degrees C using CaO center dot ZnO as catalyst (2 wt% on the basis of oil) and methanol to oil molar ratio of 10:1. Heterogeneous CaO center dot ZnO catalyst was synthesized by mechanochemical treatment of CaO and ZnO powder mixture with the addition of water necessary for the formation of corresponding mixed hydroxides, and their calcination at 700 degrees C in air. It was shown that kinetics of overall process could be described as pseudo-first order reaction. For the sunflower oil methanolysis at 60 and 70 degrees C, the rate of process at the beginning of biodiesel synthesis was limited by triglycerides mass transfer to the catalyst surface, and after that it is governed by the rate of chemical reaction at catalyst surface. At higher temperatures the influence of mass transfer resistance is almost negligible implying that the rate of chemical reaction determines the overall kinetic of biodiesel synthesis. In the case of used vegetable oil, the influence of mass transfer resistance was not observed either at higher or lower temperature. The kinetic model that describes the whole process well was proposed, and it comprises both the triglycerides mass transfer and chemical reaction controlled regime. The overall volumetric mass transfer coefficient was defined, assuming that it depends on the conversion of triglycerides.
PB  - Elsevier Sci Ltd, Oxford
T2  - Fuel
T1  - Kinetics of sunflower and used vegetable oil methanolysis catalyzed by CaO center dot ZnO
VL  - 113
SP  - 367
EP  - 378
DO  - 10.1016/j.fuel.2013.05.093
ER  - 

@article{
author = "Lukić, Ivana and Kesic, Zeljka and Maksimović, Svetolik and Zdujić, Miodrag and Liu, Hui and Krstić, Jugoslav and Skala, Dejan",
year = "2013",
abstract = "The kinetics of heterogeneous methanolysis of sunflower oil and used vegetable oil were studied at different temperatures, ranging from 60 to 96 degrees C using CaO center dot ZnO as catalyst (2 wt% on the basis of oil) and methanol to oil molar ratio of 10:1. Heterogeneous CaO center dot ZnO catalyst was synthesized by mechanochemical treatment of CaO and ZnO powder mixture with the addition of water necessary for the formation of corresponding mixed hydroxides, and their calcination at 700 degrees C in air. It was shown that kinetics of overall process could be described as pseudo-first order reaction. For the sunflower oil methanolysis at 60 and 70 degrees C, the rate of process at the beginning of biodiesel synthesis was limited by triglycerides mass transfer to the catalyst surface, and after that it is governed by the rate of chemical reaction at catalyst surface. At higher temperatures the influence of mass transfer resistance is almost negligible implying that the rate of chemical reaction determines the overall kinetic of biodiesel synthesis. In the case of used vegetable oil, the influence of mass transfer resistance was not observed either at higher or lower temperature. The kinetic model that describes the whole process well was proposed, and it comprises both the triglycerides mass transfer and chemical reaction controlled regime. The overall volumetric mass transfer coefficient was defined, assuming that it depends on the conversion of triglycerides.",
publisher = "Elsevier Sci Ltd, Oxford",
journal = "Fuel",
title = "Kinetics of sunflower and used vegetable oil methanolysis catalyzed by CaO center dot ZnO",
volume = "113",
pages = "367-378",
doi = "10.1016/j.fuel.2013.05.093"
}

Lukić, I., Kesic, Z., Maksimović, S., Zdujić, M., Liu, H., Krstić, J.,& Skala, D.. (2013). Kinetics of sunflower and used vegetable oil methanolysis catalyzed by CaO center dot ZnO. in Fuel
Elsevier Sci Ltd, Oxford., 113, 367-378.
https://doi.org/10.1016/j.fuel.2013.05.093

Lukić I, Kesic Z, Maksimović S, Zdujić M, Liu H, Krstić J, Skala D. Kinetics of sunflower and used vegetable oil methanolysis catalyzed by CaO center dot ZnO. in Fuel. 2013;113:367-378.
doi:10.1016/j.fuel.2013.05.093 .

Lukić, Ivana, Kesic, Zeljka, Maksimović, Svetolik, Zdujić, Miodrag, Liu, Hui, Krstić, Jugoslav, Skala, Dejan, "Kinetics of sunflower and used vegetable oil methanolysis catalyzed by CaO center dot ZnO" in Fuel, 113 (2013):367-378,
https://doi.org/10.1016/j.fuel.2013.05.093 . .

TY  - JOUR
AU  - Dokic, Marko
AU  - Kesic, Zeljka
AU  - Krstić, Jugoslav
AU  - Jovanović, Dušan M.
AU  - Skala, Dejan
PY  - 2012
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/949
AB  - A difficulty of biodiesel synthesis based on alkaline catalysts obviously exists if free fatty acids (FFAs) content in vegetable oil is above 0.5 wt.%. In this study, the ferric sulfate supported on silica (Fe-2(SO4)(3)/SiO2) was synthesized, activated (at different temperature: 120-600 degrees C) and tested for heterogeneous esterification of FFA (oleic acid) present in sunflower oil (5 wt.%). The catalyst samples were characterized by BET, TG/DTG, XRD and FTIR analyses. Obtained results showed that catalyst activated at 500 degrees C for 2 h in air atmosphere gave the maximal conversion of oleic acid (similar to 97%). Repeated use of catalyst without additional catalyst treatment or re-activation indicated that catalyst posses desired stability and activity. A pseudo-homogeneous kinetic model was proposed with good agreement between calculated and experimental data.
PB  - Elsevier Sci Ltd, Oxford
T2  - Fuel
T1  - Decrease of free fatty acid content in vegetable oil using silica supported ferric sulfate catalyst
VL  - 97
SP  - 595
EP  - 602
DO  - 10.1016/j.fuel.2012.03.039
ER  - 

@article{
author = "Dokic, Marko and Kesic, Zeljka and Krstić, Jugoslav and Jovanović, Dušan M. and Skala, Dejan",
year = "2012",
abstract = "A difficulty of biodiesel synthesis based on alkaline catalysts obviously exists if free fatty acids (FFAs) content in vegetable oil is above 0.5 wt.%. In this study, the ferric sulfate supported on silica (Fe-2(SO4)(3)/SiO2) was synthesized, activated (at different temperature: 120-600 degrees C) and tested for heterogeneous esterification of FFA (oleic acid) present in sunflower oil (5 wt.%). The catalyst samples were characterized by BET, TG/DTG, XRD and FTIR analyses. Obtained results showed that catalyst activated at 500 degrees C for 2 h in air atmosphere gave the maximal conversion of oleic acid (similar to 97%). Repeated use of catalyst without additional catalyst treatment or re-activation indicated that catalyst posses desired stability and activity. A pseudo-homogeneous kinetic model was proposed with good agreement between calculated and experimental data.",
publisher = "Elsevier Sci Ltd, Oxford",
journal = "Fuel",
title = "Decrease of free fatty acid content in vegetable oil using silica supported ferric sulfate catalyst",
volume = "97",
pages = "595-602",
doi = "10.1016/j.fuel.2012.03.039"
}

Dokic, M., Kesic, Z., Krstić, J., Jovanović, D. M.,& Skala, D.. (2012). Decrease of free fatty acid content in vegetable oil using silica supported ferric sulfate catalyst. in Fuel
Elsevier Sci Ltd, Oxford., 97, 595-602.
https://doi.org/10.1016/j.fuel.2012.03.039

Dokic M, Kesic Z, Krstić J, Jovanović DM, Skala D. Decrease of free fatty acid content in vegetable oil using silica supported ferric sulfate catalyst. in Fuel. 2012;97:595-602.
doi:10.1016/j.fuel.2012.03.039 .

Dokic, Marko, Kesic, Zeljka, Krstić, Jugoslav, Jovanović, Dušan M., Skala, Dejan, "Decrease of free fatty acid content in vegetable oil using silica supported ferric sulfate catalyst" in Fuel, 97 (2012):595-602,
https://doi.org/10.1016/j.fuel.2012.03.039 . .