scholarly journals GASIFICATION STUDY OF SARAWAK COALS

2017 ◽  
Vol 25 (1) ◽  
pp. 67-72
Author(s):  
Nor Fadzilah Othman ◽  
Mohd Hariffin Bosrooh
Keyword(s):  
Activation Energy ◽  
Kinetic Parameters ◽  
Arrhenius Equation ◽  
Preliminary Investigation ◽  
Reaction Model ◽  
Order Reaction ◽  
Low Rank ◽  
Heating Rates ◽  
First Order ◽  
Air Atmosphere

Thermogravimetry (TG) has been applied in a preliminary investigation, to the gasification of two low rank Sarawak coals. The coal samples, about 10 mg were investigated within the temperature range 30–900°C at different heating rate of 10, 20 and 30°C min-1, under a synthetic air atmosphere for the gasification study. The kinetic parameters were determined using Arrhenius type reaction model assuming a first-order reaction. The reactivity, RT values are fitted with Arrhenius equation at r2 = 0.83 - 0.98 for MP coal, while the RT values for MB coal are fitted with the Arrhenius equation at r2 = 0.99. The activation energy, EA for MP coal are in the range of 3.7 -4.7 kJ mol-1 and for MB coal are 7.6 - 25.6 kJ mol-1 at 3 different heating rates.  

scholarly journals Evaluation of Thermal Evolution Profiles and Estimation of Kinetic Parameters for Pyrolysis of Coal/Corn Stover Blends Using Thermogravimetric Analysis

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Abhijit Bhagavatula ◽  
Gerald Huffman ◽  
Naresh Shah ◽  
Rick Honaker
Keyword(s):  
Thermogravimetric Analysis ◽  
Kinetic Parameters ◽  
Corn Stover ◽  
Thermal Evolution ◽  
Reaction Model ◽  
Order Reaction ◽  
First Order Reaction ◽  
First Order ◽  
Temperature Regimes ◽  
Lignite Coal

The thermal evolution profiles and kinetic parameters for the pyrolysis of two Montana coals (DECS-38 subbituminous coal and DECS-25 lignite coal), one biomass sample (corn stover), and their blends (10%, 20%, and 30% by weight of corn stover) have been investigated at a heating rate of 5°C/min in an inert nitrogen atmosphere, using thermogravimetric analysis. The thermal evolution profiles of subbituminous coal and lignite coal display only one major peak over a wide temperature distribution, ~152–814°C and ~175–818°C, respectively, whereas the thermal decomposition profile for corn stover falls in a much narrower band than that of the coals, ~226–608°C. The nonlinearity in the evolution of volatile matter with increasing percentage of corn stover in the blends verifies the possibility of synergistic behavior in the blends with subbituminous coal where deviations from the predicted yield ranging between 2% and 7% were observed whereas very little deviations (1%–3%) from predicted yield were observed in blends with lignite indicating no significant interactions with corn stover. In addition, a single first-order reaction model using the Coats-Redfern approximation was utilized to predict the kinetic parameters of the pyrolysis reaction. The kinetic analysis indicated that each thermal evolution profile may be represented as a single first-order reaction. Three temperature regimes were identified for each of the coals while corn stover and the blends were analyzed using two and four temperature regimes, respectively.

scholarly journals Kajian Dehidroksilasi Termal Kaolin menjadi Metakaolin menggunakan Analisis Termogravimetri

2021 ◽  
Vol 17 (1) ◽  
pp. 105
Author(s):  
Aprilina Purbasari ◽  
Tjokorde Walmiki Samadhi
Keyword(s):  
Fourier Transform ◽  
Thermogravimetric Analysis ◽  
Fourier Transform Infrared ◽  
Reaction Model ◽  
Order Reaction ◽  
X Ray Diffraction ◽  
Exponential Factor ◽  
X Ray ◽  
First Order ◽  
Air Atmosphere

<p>Kaolin merupakan mineral yang banyak dimanfaatkan di berbagai industri. Kaolin dapat diubah menjadi metakaolin yang lebih reaktif melalui proses dehidroksilasi termal. Pada penelitian ini, proses dehidroksilasi termal kaolin dari Bangka Belitung menjadi metakaolin dikaji menggunakan analisis termogravimetri pada rentang suhu 30 – 900 °C dengan laju pemanasan 10 °C/menit dalam lingkungan atmosfer udara. Kaolin mengalami empat tahap dekomposisi dan dehidroksilasi kaolin menjadi metakaolin terjadi pada suhu sekitar 450 – 600 °C. Berdasarkan metode Coats dan Redfern, dehidroksilasi kaolin mengikuti model reaksi order satu dengan energi aktivasi 271,66 kJ/mol dan faktor pre-eksponensial 6,13×10<sup>15</sup> s<sup>-1</sup>. Hasil analisis menggunakan spektroskopi <em>X-ray diffraction</em> (XRD) dan <em>Fourier Transform Infrared </em>(FTIR) pada kaolin setelah dipanaskan pada suhu 550 °C selama 3 jam menunjukkan bahwa sebagian besar kaolin telah berubah menjadi metakaolin.</p><p><strong>Study of Thermal Dehydroxylation of Kaolin to Metakaolin using Thermogravimetric Analysis. </strong>Kaolin is a mineral that is widely used in various industries. Kaolin can be converted into metakaolin which is more reactive through thermal dehydroxylation processes. In this study, thermal dehydroxylation process of Bangka Belitung kaolin into metakaolin was studied using thermogravimetric analysis in a temperature range of 30 – 900 °C with a heating rate of 10 <sup>o</sup>C/min in an air atmosphere condition. Kaolin underwent four stages of decomposition and dehydroxylation of kaolin into metakaolin occured at temperatures around 450 – 600 °C. Based on the Coats and Redfern method, kaolin dehydroxylation followed first order reaction model with activation energy of 271.66 kJ/mol and pre-exponential factor of 6.13×10<sup>15</sup> s<sup>-1</sup>. The analysis using X-ray diffraction (XRD) dan Fourier Transform Infrared (FTIR) spectroscopy on kaolin after heating at temperature of 550 °C for 3 hours showed that most of the kaolin had turned into metakaolin.</p>

scholarly journals Effect of storage temperature on the decay of catechins and procyanidins in dark chocolate

2017 ◽  
Vol 35 (No. 4) ◽  
pp. 360-366 ◽  
Author(s):  
Pavlović Aleksandra N ◽  
Mrmošanin Jelena M ◽  
Krstić Jovana N ◽  
Mitić Snežana S ◽  
Tošić Snežana B ◽  
...  
Keyword(s):  
Activation Energy ◽  
Reaction Kinetics ◽  
Storage Stability ◽  
Arrhenius Equation ◽  
Storage Temperature ◽  
Order Reaction ◽  
Dark Chocolate ◽  
Total Flavonoids ◽  
Temperature Dependent ◽  
First Order

The storage stability of catechins, procyanidins, and total flavonoids in dark chocolate was investigated. The obtained results showed that the degradation of flavonoids followed first-order reaction kinetics. Temperature-dependent degradation was modelled on the Arrhenius equation. The activation energy for the degradation of dark chocolate flavonoids during storage was 61.2 kJ/mol. During storage, flavonoids degraded more rapidly at 35°C (k = 7.8 × 10<sup>–3</sup>/day) than at 22°C (k = 5.4 × 10<sup>–3</sup>/day) and 4°C (k = 2.2 × 10<sup>–3</sup>/day).

scholarly journals Co-Combustion Studies of Low-Rank Coal and Refuse-Derived Fuel: Performance and Reaction Kinetics

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3796
Author(s):  
Mudassar Azam ◽  
Asma Ashraf ◽  
Saman Setoodeh Setoodeh Jahromy ◽  
Sajjad Miran ◽  
Nadeem Raza ◽  
...  
Keyword(s):  
Activation Energy ◽  
Waste Management ◽  
Energy Demand ◽  
Power Plants ◽  
Combustion Process ◽  
Isoconversional Methods ◽  
Low Rank ◽  
Heating Rates ◽  
Average Activation Energy ◽  
Refuse Derived Fuel

In connection to present energy demand and waste management crisis in Pakistan, refuse-derived fuel (RDF) is gaining importance as a potential co-fuel for existing coal fired power plants. This research focuses on the co-combustion of low-quality local coal with RDF as a mean to reduce environmental issues in terms of waste management strategy. The combustion characteristics and kinetics of coal, RDF, and their blends were experimentally investigated in a micro-thermal gravimetric analyzer at four heating rates of 10, 20, 30, and 40 °C/min to ramp the temperature from 25 to 1000 °C. The mass percentages of RDF in the coal blends were 10%, 20%, 30%, and 40%, respectively. The results show that as the RDF in blends increases, the reactivity of the blends increases, resulting in lower ignition temperatures and a shift in peak and burnout temperatures to a lower temperature zone. This indicates that there was certain interaction during the combustion process of coal and RDF. The activation energies of the samples were calculated using kinetic analysis based on Kissinger–Akahira–Sunnose (KAS) and Flynn–Wall–Ozawa (FWO), isoconversional methods. Both of the methods have produced closer results with average activation energy between 95–121 kJ/mol. With a 30% refuse-derived fuel proportion, the average activation energy of blends hit a minimum value of 95 kJ/mol by KAS method and 103 kJ/mol by FWO method.

scholarly journals N.M.R. studies of ligand exchange on acetylacetonatotrimethylplatinum(IV)

1975 ◽  
Vol 28 (4) ◽  
pp. 759 ◽  
Author(s):  
NS Ham ◽  
JR Hall ◽  
GA Swile
Keyword(s):  
Activation Energy ◽  
Quantitative Analysis ◽  
Ligand Exchange ◽  
Variable Temperature ◽  
Order Reaction ◽  
First Order Reaction ◽  
First Order ◽  
Cdcl3 Solution ◽  
Made In

A quantitative analysis of the variable-temperature 1H N.M.R. spectra of acetylacetonatotrimethyl-platinum(IV) has been made. In CDCl3 solution the exchange of acetylacetonate ligands is a first-order reaction and proceeds predominantly by dissociation of the dimer into two separated five-coordinate activated complexes. The activation energy is 61.5 � 0.8 kJ mol-1.

Kinetics of Cs adsorption/desorption on granite by a pseudo first order reaction model

2007 ◽  
Vol 275 (3) ◽  
pp. 555-562 ◽  
Author(s):  
Shih-Chin Tsai ◽  
Tsing-Hai Wang ◽  
Yuan-Yaw Wei ◽  
Wen-Chun Yeh ◽  
Yi-Lin Jan ◽  
...  
Keyword(s):  
Reaction Model ◽  
Order Reaction ◽  
First Order Reaction ◽  
Pseudo First Order Reaction ◽  
First Order ◽  
Pseudo First Order ◽  
Adsorption Desorption ◽  
Kinetics Of

Pseudo-Homogenous Kinetics Model for the Synthesis of Dimethyl Carbonate from Urea and Methanol with Heterogeneous Catalyst

2011 ◽  
Vol 233-235 ◽  
pp. 481-486
Author(s):  
Wen Bo Zhao ◽  
Ning Zhao ◽  
Fu Kui Xiao ◽  
Wei Wei
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Dimethyl Carbonate ◽  
Side Reaction ◽  
Order Reaction ◽  
Zero Order ◽  
Kinetics Model ◽  
First Order ◽  
Zero Order Reaction ◽  
Kinetics Of

The synthesis of dimethyl carbonate (DMC) from urea and methanol includes two main reactions: one amino of urea is substituted by methoxy to produce the intermediate methyl carbamate (MC) which further converts to DMC via reaction with methanol again. In a stainless steel autoclave, the kinetics of these reactions was separately investigated without catalyst and with Zn-containing catalyst. Without catalyst, for the first reaction, the reaction kinetics can be described as first order with respect to the concentrations of methanol and methyl carbamate (MC), respectively. For the second reaction, the results exhibit characteristics of zero-order reaction. Over Zn-containing catalyst, the first reaction is neglected in the kinetics model since its rate is much faster than second reaction. After the optimization of reaction condition, the macro-kinetic parameters of the second reaction are obtained by fitting the experimental data to a pseudo-homogenous model, in which a side reaction of DMC synthesis is incorporated since it decreases the yield of DMC drastically at high temperature. The activation energy of the reaction from MC to DMC is 104 KJ/mol while that of the side reaction of DMC is 135 KJ/mol.

Generation and Dissociation of Iron-Boron Pairs in Silicon

1989 ◽  
Vol 163 ◽  
Author(s):  
Masashi Suezawa ◽  
Koji Sumino
Keyword(s):  
Activation Energy ◽  
Electron Paramagnetic Resonance ◽  
Reaction Kinetics ◽  
Order Reaction ◽  
Migration Energy ◽  
Paramagnetic Resonance ◽  
First Order ◽  
Pair Generation ◽  
Electron Paramagnetic ◽  
Fe Impurity

AbstractThe generation and dissociation processes of Fe-B pairs in Si crystal are investigated by means of the measurements of electron paramagnetic resonance of Si crystals of various B concentrations doped with Fe. Fe-B pairs are generated due to annealing of the crystals at temperatures around 300 K obeying to the first order reaction kinetics. The activation energy for pair generation is determined to be about 0.65 eV which is almost equal to the migration energy of Fe impurity in a Si crystal. Fe-B pairs are found to be dissociated at tempeatures higher than 150°C leading to the precipitation of Fe.

Synthesis of ethyl-6-aminohexanoate from caprolactam and ethanol in near-critical water

2014 ◽  
Vol 68 (2) ◽  
Author(s):  
Zhi Hou ◽  
Li Luo ◽  
Chun Liu ◽  
Yuan Wang ◽  
Li Dai
Keyword(s):  
Activation Energy ◽  
Reaction Mechanism ◽  
Kinetic Equation ◽  
Residence Time ◽  
Reaction Temperature ◽  
Arrhenius Equation ◽  
Order Reaction ◽  
Initial Ratio ◽  
Second Order Reaction ◽  
Water Ph

AbstractThe reaction between caprolactam and ethanol was performed in near-critical water. The primary product (ethyl-6-aminohexanoate) was identified by GC-MS. The influences of the reaction temperature, residence time, initial ratio (reactant/water), pH, and additives on the yields of ethyl-6-aminohexanoate are discussed. The results showed that the yield of ethyl-6-aminohexanoate could be as high as 98 % with SnCl2 as an additive in near-critical water. At the same time, the reaction between caprolactam and ethanol was estimated by a lumped kinetic equation as a second-order reaction in near-critical water, and the activation energy was evaluated according to the Arrhenius equation under acidic and basic conditions. Based on the results, the reaction mechanism between caprolactam and ethanol in near-critical water is proposed.

scholarly journals Kinetika Reaksi Penurunan Kafein dan Asam Klorogenat Biji Kopi Robusta melalui Pengukusan Sistem Tertutup

2018 ◽  
Vol 38 (1) ◽  
pp. 105
Author(s):  
Sapto Kuncoro ◽  
Lilik Sutiarso ◽  
Joko Nugroho Wahyu Karyadi ◽  
Rudiati Evi Masithoh
Keyword(s):  
Chlorogenic Acid ◽  
Arrhenius Equation ◽  
Order Reaction ◽  
First Order Reaction ◽  
Chlorogenic Acids ◽  
First Order ◽  
Robusta Coffee ◽  
Coffee Beans ◽  
Energy Activation ◽  
Acid Reduction

This study was aimed to examine the correlation between temperature and duration of steaming on caffeine and chlorogenic acid reduction as well as to determine energy activation (Ea) according to Arrhenius equation. About 750 g of Robusta coffee was steamed by autoclaving at 100, 110, 120 °C for 1, 2, 3, 4, 5, 6 and 7 hours. The study was conducted in 3 replications. Analyses of caffeine and chlorogenic acid were performed using HPLC.  Steaming coffee beans at 100, 110 and 120 °C resulted in the highest decrease of caffeine and chlorogenic acids content for 7 hours by 13%, 18% and 25% for caffeine; and by 37%, 50% and 59% for chlorogenic acids. At all temperatures investigated, decaffeination and chlorogenic acid reduction followed first order reaction. The decaffeination equation at 100 °C, 110 °C and  120 °C followed equation of  y = -0.019x + 0.862, y = -0.023x + 0.820, and y = -0.033x + 0.759, respectively. Meanwhile, the chlorogenic acid reduction at 100 °C, 110 °C,  and 120 °C followed equation of y = -0.071x + 1.421, y = -0.089x + 1.271, and y = -0.120x + 1.201. Activation energies of decaffeination and chlorogenic acid reduction were 33,543.66 kJ/mol K and 31,934.91 kJ/mol K, respectively. ABSTRAKPenelitian ini bertujuan untuk mengkaji hubungan antara suhu dan lama pengukusan terhadap penurunan kandungan kafein dan asam klorogenat serta menentukan energi aktivasi (Ea) dengan pendekatan persamaan Arrhenius. Biji kopi Robusta masing-masing seberat 750 g dikukus dalam autoklaf (sistem tertutup) pada suhu 100, 110, dan 120 °C masing-masing selama 1, 2, 3, 4, 5, 6, dan 7 jam. Penelitian dilakukan dengan 3 kali ulangan. Analisis kafein dan asam klorogenat dilakukan menggunakan HPLC. Pengukusan biji kopi pada suhu 100, 110, dan 120 °C, menghasilkan penurunan kandungan kafein dan asam klorogenat tertinggi pada pengukusan selama 7 jam. Penurunan kandungan kafein selama 7 jam pada suhu pengukusan 100, 110, dan 120 °C berturut-turut 13%, 18%, dan 25%. Kandungan asam klorogenat mengalami penurunan 37%, 50%, dan 59% berturut-turut pada suhu 100, 110, dan 120 °C.  Pada semua suhu yang diuji, penurunan kafein dan asam klorogenat mengikuti reaksi orde satu. Penurunan kafein mengikuti persamaan y = -0,019x + 0,862,  y = -0,023x + 0,820, dan y = -0,033x + 0,759, sedangkan untuk asam klorogenat mengikuti persamaan y = -0,071x + 1,421,  y = -0,089x + 1,271, dan y = -0,120x + 1,201. Besarnya energi aktivasi penurunan kafein dan asam klorogenat berturut turut adalah 33.543,66 kJ/molK dan 31.934,91 kJ/Mok.

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