Study on Mechanism of Low Temperature Co-Pyrolysis of Duckweed and Flame Coal

2013 ◽  
Vol 724-725 ◽  
pp. 300-305
Author(s):  
Xuan Ming He ◽  
Jia Qi Fang ◽  
Ye Pan ◽  
Wei Li ◽  
Xiao Juan Wang
Keyword(s):  
Activation Energy ◽  
Low Temperature ◽  
Synergistic Effect ◽  
Kinetic Analysis ◽  
Kinetic Parameters ◽  
Pyrolysis Temperature ◽  
Light Component ◽  
Average Activation Energy ◽  
First Order ◽  
Pyrolysis Characteristics

Co-pyrolysis characteristics of long flame coal mixed with duckweed in different proportions were studied by using TG. And the kinetic parameters was also figured out by using the method of Coats-Redfern. It was exhibited significant synergistic effect created more the light component between duckweed and coal during co-pyrolysis, The pyrolysis rate of flame coal is much smaller than biomass, and the starting pyrolysis temperature of flame coal is higher than biomass. The kinetic analysis indicated that the pyrolytic processes can be described as first order reactions model. The average activation energy of duckweed and coal was 39.14kJ/mol and 46.43kJ/mol , and with the increasing of the duckweed proportion, pyrolysis activation energy was decreased.

Thermogravimetric Analysis of Glucose-Based and Fructose-Based Carbohydrates

2013 ◽  
Vol 805-806 ◽  
pp. 265-268 ◽  
Author(s):  
Fang Ming Cui ◽  
Xiao Yuan Zhang ◽  
Li Min Shang
Keyword(s):  
Activation Energy ◽  
Thermogravimetric Analysis ◽  
Kinetic Parameters ◽  
Degree Of Polymerization ◽  
Experiment Data ◽  
Pyrolysis Characteristics ◽  
The Difference ◽  
Kinetic Calculations

Thermogravimetric analysis (TGA) was employed to study the pyrolysis characteristics of four glucose-based and three fructose-based carbohydrates. Kinetic parameters were calculated based on the experiment data. The results indicated that the starting and maximal pyrolysis temperatures of the glucose-based carbohydrates were increased steadily as the rising of their degree of polymerization (DP). The fructose-based carbohydrates exhibited similar pyrolysis behaviors as the glucose-based carbohydrates, but the difference was smaller. Kinetic calculations revealed that the activation energy values of the glucose-based carbohydrates were higher than those of the fructose-based carbohydrates, indicating the glucose-based carbohydrates were more difficult to decompose than the fructose-based carbohydrates.

Fluidized Bed Kinetics for Hydrogen Production Through Steam Iron Oxidation

2013 ◽  
Author(s):  
Fotouh Al-Raqom ◽  
James F. Klausner
Keyword(s):  
Activation Energy ◽  
Hydrogen Production ◽  
Kinetic Analysis ◽  
Fluidized Bed ◽  
Time Scale ◽  
Graphical Representation ◽  
Iron Oxidation ◽  
Scale Analysis ◽  
First Order ◽  
Reduced Time

Kinetic analysis is essential for chemical reactor modeling. This study proposes a methodology to use available kinetic analysis methodologies, including conventional (modelistic) graphical representation, isoconversional (model free), models based on first principles and reduced time scale analysis (Sharp and Hancock procedure) to predict the kinetics of an investigated reaction. Even though these methods have some limitations, a methodology comprised of combining their results can help in determining the kinetic parameters for reaction. The isoconversional approach can be used to determine the activation energy without the need of using a reaction model. The modelistic graphical representation can aid is determining the group (i.e. diffusion, first order, phase boundary or nucleation) to which the reaction generally belongs. The reduced time scale analysis can guide in isolating the reaction kinetics in the early stages of the reaction when the conversion ranges between 0.15 and 0.5. This proposed methodology uses the various methods and applies them to experimental data for high temperature reactions in fluidized bed reactors. Particular attention is given to steam driven iron oxidation kinetics for hydrogen production. When only the modelistic approach is used, the activation energy computed using the selected models varies from 59–183 kJ/mol, depending on the model used. However, by combining the predictive capabilities of various approaches discussed in this study, the activation energy range narrows to 80–147 kJ/mol. It is also shown that the iron oxidation with steam under the studied conditions can be described by a combination of two models. The early stage of the reaction is represented by either a contracting volume or first order model. Later stages of reaction can be described by either a contracting volume, first order or 3-D diffusion model. In addition, when analyzing reaction kinetics using a fundamental approach, it is observed that the fluidized bed oxidation reaction of iron with pure steam can be best represented by a combination of two mechanisms, namely shrinking sphere surface area and diffusion controlled mechanisms and the estimated activation energy is 103 kJ/mol.

The Vulcanization of Elastomers. XI. The Vulcanization of Natural Rubber with Sulfur in the Presence of Mercaptobenzothiazole. I

1957 ◽  
Vol 30 (3) ◽  
pp. 911-927 ◽  
Author(s):  
Otto Lorenz ◽  
Elisabeth Echte
Keyword(s):  
Activation Energy ◽  
Zinc Oxide ◽  
Natural Rubber ◽  
Kinetic Analysis ◽  
Rate Constants ◽  
Network Formation ◽  
Zinc Salt ◽  
Kcal Mole ◽  
Minimum Quantity ◽  
First Order

Abstract 1. The decrease of free sulfur occurs according to the first order law during the vulcanization of natural rubber accelerated by mercaptobenzothiazole in the presence of zinc oxide. The activating energy for this reaction amounts to 30.5 kcal./mole. 2. If zinc benzothiazolylmercaptide is used as an accelerator, one obtains the same rate constants for the sulfur decrease as in the presence of mercaptobenzothiazole. These seem to be equivalent as regards their effectiveness of acceleration. 3. A kinetic analysis of the reciprocal swelling, which represents a measure of network formation, indicates that the reaction is first order. Sulfur decrease and reciprocal swelling prove to be equal processes as regards rate. This is true where vulcanization is accelerated with mercaptobenzothiazole or with the zinc salt. 4. During vulcanization there occurs a decrease of accelerator concentration. This is dependent upon the temperature and is tied in with the combination sulfur with rubber. 5. If the quantity of the accelerator added is changed, the rate constants for sulfur decrease and for reciprocal swelling do not change, provided that a minimum quantity of accelerator is present. 6. In vulcanization accelerated with zinc benzothiazolylmercaptide, zinc oxide being absent, sulfur decrease again occurs according to the first order law but considerably faster, without thereby changing the activation energy. These investigations are being continued and the results will be discussed in detail in relation to other published contributions in this field.

Pyrolysis Characteristics and Kinetics of Cassava Residues

2014 ◽  
Vol 953-954 ◽  
pp. 325-329
Author(s):  
Jin Wei Jia ◽  
Di Yang ◽  
He Long Hui ◽  
Xing Min Fu ◽  
Lu Liu ◽  
...  
Keyword(s):  
Activation Energy ◽  
Kinetic Parameters ◽  
Fixed Bed ◽  
The Other ◽  
Fixed Bed Reactor ◽  
Biomass Feedstock ◽  
Pyrolysis Characteristics ◽  
Three Samples ◽  
Bio Oil ◽  
Kinetics Of

The aims of this work were to investigate the influence of feedstock properties of different part of cassava residues (cassava rhizome (CR), cassava stalk (CS) and cassava leaf (CL)) and operating temperatures on the pyrolysis characteristics and the kinetic parameters. Pyrolysis experiments of three selected biomass feedstock were conducted using a fixed-bed reactor. It was shown that the bio-oil yield of cassava stalk reached the maxima at 600°C, and the char yield reduced with the temperature, whereas the gas yield increased with temperature. The cassava rhizome presented higher thermochemical reactivity than the other samples. The activation energy of cassava stalks was 37.57 kJ / mol and that of cassava rhizome (39.42 kJ / mol) increased slightly. The activation energy of cassava leaf (22.85 kJ / mol) was lowest of the three samples.

The conformation and reorientation of enclathrated 1,2-dichloroethane

1979 ◽  
Vol 57 (6) ◽  
pp. 635-637 ◽  
Author(s):  
S. K. Garg ◽  
D. W. Davidson ◽  
S. R. Gough ◽  
J. A. Ripmeester
Keyword(s):  
Activation Energy ◽  
Low Temperature ◽  
Dihedral Angle ◽  
Line Shape ◽  
Guest Molecule ◽  
Spectral Simulation ◽  
Rigid Lattice ◽  
Average Activation Energy ◽  
Dielectric Absorption

The rigid-lattice nmr line shape of the four-proton system in 1,2-dihaloethanes has been obtained by spectral simulation as a function of dihedral angle [Formula: see text] and used to show that 1,2-dichloroethane is encaged in the structure II hydrate in a gauche configuration with [Formula: see text] Very broad low-temperature dielectric absorption is associated with an average activation energy of 0.87 kcal/mol for guest-molecule reorientation.

scholarly journals Thermal and kinetic analysis of pure and contaminated ionic liquid: 1-butyl-2.3-dimethylimidazolium chloride (BDMIMCl)

2016 ◽  
Vol 18 (2) ◽  
pp. 122-125 ◽  
Author(s):  
Ayyaz Muhammad
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Thermal Decomposition ◽  
Ionic Liquid ◽  
Thermal Degradation ◽  
Kinetic Analysis ◽  
Kinetic Parameters ◽  
Process Design ◽  
Research Work ◽  
Thermal Stability Of

Abstract In this research work, thermal decomposition and kinetic analysis of pure and contaminated imidazolium based ionic liquid (IL) has been investigated. As thermal decomposition and kinetics evaluation plays a pivotal role in effective process design. Therefore, thermal stability of pure 1-butyl-2,3-dimethylimidazolium chloride (BDMIMCl) was found to be higher than the sample of IL with the addition of 20% (wt.) NH4Cl as an impurity. The activation energy of thermal degradation of IL and other kinetic parameters were determined using Coats Redfern method. The activation energy for pure IL was reduced in the presence of NH4Cl as contaminant i.e., from 58.7 kJ/mol to 46.4 kJ/mol.

Thermogravimetric Study on the Co-Pyrolysis Characteristics of Bituminous Coal and Wheat Straw

2014 ◽  
Vol 1070-1072 ◽  
pp. 146-151
Author(s):  
Xin Ping Yan ◽  
Ji Song Bai ◽  
Xiong Zhou ◽  
Shun Hong Lin
Keyword(s):  
Activation Energy ◽  
Thermogravimetric Analysis ◽  
Wheat Straw ◽  
Bituminous Coal ◽  
Synergistic Effects ◽  
Order Reaction ◽  
Pyrolysis Process ◽  
First Order ◽  
Pyrolysis Characteristics ◽  
Apparent Kinetic Parameters

In this work, the pyrolysis behavior of bituminous coal (BC) wheat straw (WS) and the blends were investigated by thermogravimetric analysis. It was found that the main thermal degradation stage of BC and WS lies in different temperature range and there is nearly no overlapping. Interaction was observed during the co-pyrolysis process of BC and WS. At high temperatures, the volatile releasing is slightly inhibited by WS addition. Coats-Redfern method was used to analyze the apparent kinetic parameters. The results indicated that both the two reaction stages during pyrolysis process are well correlated by first-order reaction. The variation trend of activation energy value further confirm the synergistic effects between BC and WS. The experimental results may provide useful data for co-thermochemical utilization of biomass with coal.

scholarly journals Pyrolytic and Kinetic Analysis of Two Coastal Plant Species:Artemisia annuaandChenopodium glaucum

2013 ◽  
Vol 2013 ◽  
pp. 1-7
Author(s):  
Lili Li ◽  
Xiaoning Wang ◽  
Jinsheng Sun ◽  
Yichen Zhang ◽  
Song Qin
Keyword(s):  
Activation Energy ◽  
Kinetic Analysis ◽  
Plant Species ◽  
Energy Production ◽  
Artemisia Annua ◽  
Frequency Factor ◽  
Distributed Activation Energy Model ◽  
First Order ◽  
Coastal Plant ◽  
Simplified Mathematical Model

The large amount of coastal plant species available makes them ideal candidates for energy production. In this study, thermogravimetric analysis was used to evaluate the fuel properties of two coastal plant species, and the distributed activation energy model (DAEM) was employed in kinetic analysis. The major mass loss due to devolatilization started at 154 and 162°C at the heating rate of 10°C min−1forArtemisia annuaandChenopodium glaucum, respectively. The results showed that the average activation energies ofArtemisia annuaandChenopodium glaucumwere 169.69 and 170.48 kJ mol−1, respectively. Furthermore, the activation energy changed while the conversion rate increased, and the frequency factork0decreased greatly while the activation energy decreased. The results also indicated that the devolatilization of the two coastal plant species underwent a set of first-order reactions and could be expressed by the DAEM. Additionally, a simplified mathematical model was proposed to facilitate the prediction of devolatilization curves.

Study of Co-pyrolysis Characteristics of Lignite and Rice Husk in a TGA and a Fixed-Bed Reactor

2013 ◽  
Vol 11 (1) ◽  
pp. 479-488 ◽  
Author(s):  
Wenju Wang ◽  
Xiaobing Zhang ◽  
Yunhua Li
Keyword(s):  
Synergistic Effect ◽  
Rice Husk ◽  
Fixed Bed ◽  
Kinetic Studies ◽  
Order Reaction ◽  
Fixed Bed Reactor ◽  
First Order Reaction ◽  
First Order ◽  
Pyrolysis Characteristics ◽  
Exponential Factors

Abstract Co-pyrolysis characteristics of lignite and rice husk blend were determined in TGA and a fixed-bed reactor. From TGA results, the weight loss rate of lignite and rice husk blend increases at 250–400°C. In a fixed bed at programmed temperature condition, the synergistic effect to produce more volatiles is appeared at 500–700°C, and the maximum synergistic effect exhibits with a rice husk blending ratio of 0.8. The gas yield of co-pyrolysis of lignite and rice husk blend was higher than that of the sum of lignite and rice husk individually. The kinetic studies were performed according to Coats–Redfern method for first-order reaction. It was found that the pyrolysis process of lignite and rice husk could be described by one first-order reaction and two consecutive first-order reactions, respectively. However, for lignite and rice blends, this process can be described by three consecutive first-order reactions. The estimated kinetic parameters, viz., activation energies and pre-exponential factors for lignite, rice husk and their blends, were found to be in the range of 63.5–477.8 kJ/mol and 1.4 × 103–6.5 × 1047 min−1, respectively.

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