scholarly journals Kinetics of Transesterification of Croton megalocarpus Oil Using Alkaline Earth Catalysts with Conventional and Microwave Heating

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Anil Kumar ◽  
Henry K. Kiriamiti
Keyword(s):  
Microwave Irradiation ◽  
Alkaline Earth ◽  
Heterogeneous Catalysts ◽  
Methyl Esters ◽  
Chemical Properties ◽  
Reaction Rates ◽  
Conventional Heating ◽  
Reaction Rate Constants ◽  
Scanning Electron Micrography ◽  
Kinetics Of

Transesterification kinetics of Croton megalocarpus oil to produce fatty acid methyl esters (FAME) was studied using homogeneous NaOH and heterogeneous alkaline earth Nano MgO, MgO, Nano CaO, CaO, Reoxidized CaO, SrO, and BaO catalysts. Characteristic surface, bulk, and chemical properties of the heterogeneous catalysts were obtained which included surface area, pore properties, scanning electron micrography, X-ray diffraction, basic strength, and basicity. The catalyst porosity varied as Nano MgO > Nano CaO > MgO > CaO > CaO-RO > SrO > BaO and basicity as BaO > SrO > Nano CaO > CaO RO > CaO > Nano MgO > MgO. Catalysts NaOH, BaO, SrO, and Nano CaO gave a good FAME yield (>50%), and reaction order and rate constant have been reported for these catalysts, for both conventional heating and microwave irradiation. The overall reaction for NaOH was of 1st order for microwave irradiation with respect to triglyceride and of 2nd order with respect to triglyceride under conventional heating. For the heterogeneous catalysts, the overall reaction was of 3rd order, 2nd order with respect to triglyceride and 1st order with respect to methanol for both heating methods. Reaction rate constants for microwave irradiation were higher than those for conventional heating due to faster reaction rates under such heating. BaO was the most active heterogeneous catalyst, followed by SrO and Nano CaO, which was in accordance with their basicity.

scholarly journals Comparative kinetics of the alkali-catalyzed sunflower oil methanolysis with co-solvent under conventional and microwave heating with controlled cooling

2018 ◽  
Vol 7 (5) ◽  
pp. 441-452
Author(s):  
Biljana B. Beljic Durkovic ◽  
Jelena D. Jovanovic ◽  
Borivoj K. Adnadjevic
Keyword(s):  
Microwave Heating ◽  
Sunflower Oil ◽  
Conventional Heating ◽  
Controlled Cooling ◽  
Pseudo First Order Reaction ◽  
Reaction Rate Constants ◽  
Cooling Conditions ◽  
Exponential Factors ◽  
The Impact ◽  
Kinetics Of

Abstract The kinetics of the alkali-catalyzed transesterification of sunflower oil with methanol in the presence of co-solvent (TSMPC) were investigated. The kinetics curves of the alkali-catalyzed TSMPC, in the temperature range of 26°C–55°C, were measured for conventional heating (CH) and microwave heating with controlled cooling. The results showed that for both heating modes, the kinetics of the alkali-catalyzed TSMPC reaction can be described with the kinetic model of the pseudo first-order reaction with respect to the concentration of the triglycerides. The values of apparent reaction rate constants, activation energies, and pre-exponential factors are also calculated. The existence of a linear correlation (compensation effect) between the values of apparent kinetic parameters determined for CH and microwave heating with controlled cooling conditions is established. The results confirmed that the increase in the transesterification rate in the microwave heating with controlled cooling conditions is not caused by overheating nor by the existence of hotspots. The model of mechanism of the impact of microwave heating on the kinetics of transesterification is hereby proposed.

scholarly journals Current Issues in Sol-Gel Reaction Kinetics

1990 ◽  
Vol 180 ◽  
Author(s):  
Roger A. Assink ◽  
Bruce D. Kay
Keyword(s):  
Reaction Kinetics ◽  
Sol Gel ◽  
Early Time ◽  
Acid Catalyst ◽  
Reaction Rates ◽  
Reaction Conditions ◽  
Reaction Rate Constants ◽  
Condensation Reactions ◽  
Experimental Findings ◽  
Kinetics Of

ABSTRACTThis paper surveys a few of the current issues in sol-gel reaction kinetics. Many times seemingly modest changes in reactants or reaction conditions can lead to substantial differences in the overall reaction rates and pathways. For example, qualitative features of the reaction kinetics can depend on catalyst concentration. At very high acid-catalyst concentrations, reverse reactions are significant for TMOS solgels, while for moderate acid-catalyst concentrations, reverse reactions are substantially reduced. The reaction kinetics of two similar tetraalkoxysilanes: tetramethoxysilane (TMOS) and tetraethoxysilane (TEOS), can be markedly different under identical reaction conditions. Under acid-catalyzed reaction conditions, a TMOS sol-gel undergoes both water- and alcoholproducing condensation reactions while a TEOS sol-gel undergoes only water-producing condensation. The early time hydrolysis and condensation reactions of a TMOS sol-gel are statistical in nature and can be quantitatively described by a few simple reaction rate constants while the reaction behavior of a TEOS sol-gel is markedly nonstatistical. A comprehensive theory of sol-gel kinetics must address these diverse experimental findings.

scholarly journals Effects of Microwave Irradiation on Activation Energy and Reaction Rate of Synthesis of Dodecylmethyldihydroxyl Ammonium Bromide

2011 ◽  
Vol 396-398 ◽  
pp. 1044-1047 ◽  
Author(s):  
Tao Yan Mao ◽  
Cheng Zheng ◽  
Jimmy Yu
Keyword(s):  
Activation Energy ◽  
Microwave Irradiation ◽  
Reaction Rate ◽  
Conventional Heating ◽  
Irradiation Condition ◽  
Ammonium Bromide ◽  
Reaction Conditions ◽  
First Order ◽  
Conventional Condition ◽  
Kinetics Of

The reaction kinetics of the synthesis of quaternary ammonium salt under two sets of different reaction conditions, including microwave irradiation condition and conventional heating condition, were studied. In order to make sure that the microwave would not be interrupted, the reaction temperature was maintained at the boiling point of reaction solvents. The results showed that the reaction was a first-order reaction under both set of conditions and microwave irradiation changed the value of the activation energy of the reaction, indicating a change in the reaction mechanism. The activation energy was 41.44 kJ/mol under microwave irradiation condition, and 61.21 kJ/mol under conventional condition.

Kinetics of transesterification of palm oil under conventional heating and microwave irradiation, using CaO as heterogeneous catalyst

Fuel ◽  
2016 ◽  
Vol 180 ◽  
pp. 574-579 ◽  
Author(s):  
Wei Ye ◽  
Yujie Gao ◽  
Hui Ding ◽  
Mingchao Liu ◽  
Shejiang Liu ◽  
...  
Keyword(s):  
Microwave Irradiation ◽  
Heterogeneous Catalyst ◽  
Palm Oil ◽  
Conventional Heating ◽  
Kinetics Of

Effect of Hydration-Dehydration Activation on the Basic Strength of Nano Structured Alkaline Earth Metal Calcium Oxide

2011 ◽  
Vol 383-390 ◽  
pp. 3835-3839 ◽  
Author(s):  
Hidayah Mohd Aziz ◽  
Noor Idayu Masrom ◽  
Nur Fatin Sulaiman ◽  
Mohd Khairul Asyraf Amat Mustajab ◽  
Abdul Rahim Yacob
Keyword(s):  
Alkaline Earth ◽  
Heterogeneous Catalysts ◽  
Surface Defects ◽  
Chemical Properties ◽  
Earth Metal ◽  
Titration Method ◽  
Activation Temperature ◽  
Back Titration ◽  
Surface Cavity ◽  
Basic Strength

The study of physicochemical properties such as surface area, particle size and basicity of heterogeneous catalysts is in great interest nowadays. CaO yield a number of surface defects centers and these were important especially for heterogeneous catalyst. In this study, nano structured CaO was synthesized via hydration-dehydration method. The basic strength of the prepared CaO was also studied using simple back titration method with respect to the activation temperature. This result revealed that, the basic strength increases with the increasing of activation temperature. As the nano structured CaO were prepared, more surface cavity and defect were expected to be present and thus, exposing more O2- sites, which influences the basic strength. Finally it was found that nano structured CaO was successfully prepared, while compared to the commercial CaO have a better chemical properties for catalytic chemical reactions.

scholarly journals Microwave-Assisted Noncatalytic Esterification of Fatty Acid for Biodiesel Production: A Kinetic Study

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2167
Author(s):  
Hoang Chinh Nguyen ◽  
Fu-Ming Wang ◽  
Kim Khue Dinh ◽  
Thanh Truc Pham ◽  
Horng-Yi Juan ◽  
...  
Keyword(s):  
Microwave Irradiation ◽  
Microwave Power ◽  
Reaction Model ◽  
Biodiesel Production ◽  
Conventional Heating ◽  
Molar Ratio ◽  
Reaction Rate Constants ◽  
Microwave Assisted ◽  
Reaction Conversion ◽  
Biodiesel Synthesis

This study developed a microwave-mediated noncatalytic esterification of oleic acid for producing ethyl biodiesel. The microwave irradiation process outperformed conventional heating methods for the reaction. A highest reaction conversion, 97.62%, was achieved by performing esterification with microwave irradiation at a microwave power of 150 W, 2:1 ethanol:oleic acid molar ratio, reaction time of 6 h, and temperature of 473 K. A second-order reaction model (R2 of up to 0.997) was established to describe esterification. The reaction rate constants were promoted with increasing microwave power and temperature. A strong linear relation of microwave power to pre-exponential factors was also established, and microwave power greatly influenced the reaction due to nonthermal effects. This study suggested that microwave-assisted noncatalytic esterification is an efficient approach for biodiesel synthesis.

scholarly journals Kinetics of N<sub>2</sub>O production and reduction in a nitrate-contaminated aquifer inferred from laboratory incubation experiments

2010 ◽  
Vol 7 (1) ◽  
pp. 503-543 ◽  
Author(s):  
D. Weymann ◽  
H. Geistlinger ◽  
R. Well ◽  
C. von der Heide ◽  
H. Flessa
Keyword(s):  
Field Measurements ◽  
Reaction Rates ◽  
15N Tracer ◽  
Autotrophic Denitrification ◽  
N2o Production ◽  
Reaction Rate Constants ◽  
Laboratory Incubation ◽  
In Situ Conditions ◽  
Kinetics Of ◽  
Heterotrophic Denitrification

Abstract. Knowledge of the kinetics of N2O production and reduction in groundwater is essential for the assessment of potential indirect emissions of the greenhouse gas. In this study, we investigated this kinetics using a laboratory approach. The results were compared to field measurements in order to examine their transferability to the in situ conditions. The study site was the unconfined, predominantly sandy Fuhrberger Feld aquifer in Northern Germany. A special characteristic of the aquifer is the occurrence of the vertically separated process zones of heterotrophic denitrification in the surface groundwater and of autotrophic denitrification in the deeper groundwater, respectively. The kinetics of N2O production and reduction in both process zones was studied during long-term anaerobic laboratory incubations of aquifer slurries using the 15N tracer technique. We measured N2O, N2 and NO3− concentrations as well as parameters of the aquifer material that were related to the relevant electron donors, i.e. organic carbon and sulfur. The anaerobic incubations showed a low denitrification activity of heterotrophic denitrification with initial rates between 0.0002 and 0.0133 mg N kg−1 day−1. The process was carbon limited due to the poor availability of its electron donor. In the autotrophic denitrification zone, initial denitrification rates were considerably higher, ranging between 0.0303 and 0.1480 mg N kg−1 d−1 and NO3− as well as N2O were completely removed within 60 to 198 days. N2O accumulated during heterotrophic and autotrophic denitrification, but maximum concentrations were substantially higher during the autotrophic process. The results revealed a satisfactory transferability of the laboratory incubations to the field scale for autotrophic denitrification, whereas the heterotrophic process less reflected the field conditions due to considerably lower N2O accumulation during laboratory incubation. Finally, we applied a conventional model using first-order-kinetics to determine the reaction rates of the NO3−-to-N2O step and the N2O-to-N2 step, and evaluated the reaction rate constants for both steps. The model yielded fits to the experimental data that were of limited goodness, indicating that a more sophisticated approach is essential to describe the investigated reaction kinetics satisfactorily.

scholarly journals Estimation of Reaction Rates of Transesterification Pathways

2021 ◽  
Vol 3 ◽  
Author(s):  
Mario Alberto Pérez-Méndez ◽  
Gladys Jiménez-García ◽  
Rafael Huirache-Acuña ◽  
Rafael Maya-Yescas
Keyword(s):  
Sodium Hydroxide ◽  
Fatty Acid Methyl Esters ◽  
Reaction Rate ◽  
Methyl Esters ◽  
Reaction Rates ◽  
Reaction Engineering ◽  
Reaction Pathways ◽  
Chemical Reactors ◽  
Acid Methyl ◽  
Kinetics Of

Experimental estimation of reaction rates is a common aspect of reaction engineering because reaction kinetics are the base of the design of chemical reactors. However, it is not easy to follow complex reactions as it is the case of transesterification of triglycerides in presence of sodium hydroxide. Identifying the possible reaction pathways taking place as ionic and sequential, starting with the inorganic formation of methoxide, and followed by each one of the three organic transesterification steps of virgin soybean oil, deeper understanding about kinetics of this reacting path has been obtained. Reaction rate evaluations were performed by following the solution’s pH, based on a 24–1 design of experiments, making possible to estimate the rate constants. Additionally, it was observed that there is an optimum amount of sodium hydroxide feed to the process, therefore it is possible to minimize its addition, which favors diminishing the volume of leaching water. The best yield to fatty acid methyl esters, using the minimum amount of sodium hydroxide, was 98.84 wt%, which is highly competitive.

Evaluation of microwave irradiation effects on nutritive value of broom sorghum grain using an in vitro gas production technique

2009 ◽  
Vol 2009 ◽  
pp. 182-182
Author(s):  
F Parnian ◽  
A Taghizadeh
Keyword(s):  
Microwave Irradiation ◽  
Nutritive Value ◽  
Gas Production ◽  
Conventional Heating ◽  
Production Technique ◽  
Heating Rates ◽  
Broom Sorghum ◽  
Sorghum Grain ◽  
Kinetics Of

In Iran various varieties of sorghum (Sorghum vulgare) are planted mainly for broom production but also for use in animal nutrition. There appears to be no documented research about nutritive value of microwave processed sorghum grain. With microwave irradiation, heat is generated throughout the material, leading to faster heating rates and shorter processing times compared to conventional heating, where heat is usually transferred from the surface to the interior (Fakhouri and Ramaswamy, 1993). In the in vitro gas production method for predicting nutritive value, the kinetics of fermentation can be studied on a single sample and therefore a relatively small amount of sample is required or a larger number of samples can be evaluated at any one time. Gas production measurement provides useful data on digestion kinetics of both soluble and insoluble fractions of feedstuffs (Getachew et al., 1998). The purpose of this study was to evaluate effects of microwave irradiation on nutritive value of broom sorghum grain using the in vitro gas production technique.

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