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1.
S. Xiu H. K. Rojanala A. Shahbazi E. H. Fini L. Wang 《Journal of Thermal Analysis and Calorimetry》2012,107(2):823-829
Pyrolysis and combustion characteristics of bio-oil derived from swine manure were investigated using thermogravimetry techniques.
Thermogravimetric analysis of the bio-oils were carried out in O2 and N2 atmosphere under different heating rates (5–20 °C/min) to a maximum temperature of 900 °C. The results indicate that the
combustion processes of bio-oil occurred in three stages, namely the water and the lighter compound evaporation, i.e., the
release of the volatile compounds, ignition and burning of the heavier compounds (mainly carbon), and finally decomposition
of the carbonate compounds. The effect of heating rate was also studied, and higher heating rates were found to facilitate
the combustion process. Different reaction kinetic mechanisms were used to treat TG data, and showed that diffusion models
are the best fit for describing the combustion of bio-oil in air. The kinetic parameters of the three stages were determined
using Coats–Redfern method. The study provided reliable basic data for the burning of bio-oil. 相似文献
2.
C. Li Y. Yamamoto M. Suzuki D. Hirabayashi K. Suzuki 《Journal of Thermal Analysis and Calorimetry》2009,95(3):991-997
TG and DTA experiments were performed to investigate the biomass tar combustion behavior in coexistence of dolomite and mayenite
at two different heating rates as 5 and 15°C min−1. Different reaction kinetic mechanisms with the classical Arrhenius model were used to treat TG data, and showed that the
first-order combustion model fitted the data well. Three stages combustion model was proposed and applied for the calculation
of kinetics parameters successfully. The starting temperature of high temperature combustion stage moved up near 100°C because
of the coexistence catalysts, and the combustion amount of biomass of the stage also improved nearly 10 mass%. By calculation
a uniform trend of decreasing activation energies was observed with the addition of dolomite and mayenite, and also greatly
improved the amount and speed of tar combustion process. 相似文献
3.
M. V. Kök 《Journal of Thermal Analysis and Calorimetry》2007,88(3):663-668
In this research, non-isothermal combustion and kinetics of Silopi (Turkey) asphaltite samples were investigated by differential
scanning calorimetry (DSC) and thermogravimetry (TG/DTG). A sample size of 10 mg, heating rates of 5, 10, 15 and 20°C min−1 were used in the temperature range of 20–600°C, under air atmosphere. Two reaction regions were observed in DSC curves. The
first region is due to the evaporation of moisture in asphaltite sample whereas, release of volatile matter and burning of
carbon is called the second region.
A general computer program was developed and the results of four different kinetic models (Arrhenius, Coats-Redfern, Ingraham-Marrier
and Horowitz-Metzger) are compared and discussed with regards to their accuracy and the ease of interpretation of the kinetics
of thermal decomposition. In general similar activation energy values were obtained when the kinetic models are compared with
each other. It was also observed that there was no general trend in the activation energy values from the point of heating
rates. 相似文献
4.
This research was aimed
to investigate the role of clay on the combustion and kinetic behavior of
crude oils in limestone matrix. For this purpose, simultaneous TG (thermogravimetry)
and DTA (differential thermal analysis) experiments were performed at three
different heating rates as 10–15 and 20°C min–1,
respectively. A uniform trend of decreasing activation energies was observed
with the addition of clay. It was concluded that clays surface area affects
the values of Arrhenius constant, while it is the catalytic properties of
clay, which lower the activation energies of all the reactions, involved in
the combustion process. 相似文献
5.
Kök M. V. Pokol G. Keskin C. Madarász J. Bagci S. 《Journal of Thermal Analysis and Calorimetry》2004,75(3):781-789
In this study the combustion characteristics of crude oils (Karakuę and Beykan) in the presence of a limestone matrix were
determined using the thermogravimetry (TG/DTG). Experiments were performed at a heating rate of 10°C min-1, whereas the air flow rate was kept constant at 10 L h-1 in the temperature range of 20-900°C. In combustion with air, three distinct reaction regions were identified in all crude
oil/limestone mixtures studied known as low temperature oxidation (LTO), fuel deposition (FD) and high temperature oxidation
(HTO). The individual activation energies for each reaction region may be attributed to different reaction mechanisms, but
they do not give any indication of the contribution of each region to the overall reactivity of the crude oils. Depending
on the characteristics, the mean activation energy of samples varied between 50.3 and 55.8 kJ mol-1.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
6.
High pressure thermogravimetric analysis (HPTG) was used in order to study the oxidation of crude oil in a porous medium under pressurised conditions for simulation of in-situ combustion during oil recovery. Three distinct reaction regions were observed from the HPTG curves in an oxidising environment subjected to a constant heating rate. These were low temperature oxidation, fuel deposition and high temperature oxidation. The method of Coats and Redfern was used to obtain kinetic parameters and the results are discussed.The authors would like to express their appreciation for the financial support of TUBITAK (The Scientific and Technical Research Council of Turkey) and the Royal Society. 相似文献
7.
Kinetics of thermal degradation of wood biomass 总被引:1,自引:0,他引:1
Pyrolysis kinetics of a hardwood representative, beech (Fagus sylvatica), was investigated by two different kinetic approaches: model-free isoconversional method and model-fitting method. The model-free isoconversional method was used for the determination of apparent kinetic parameters, i.e. the activation energy and pre-exponential factor. The model fitting method was used for the optimization of kinetic parameters of the reaction pathways of three selected reaction mechanisms: one-step, two-step, and three-step one. In both approaches, thermo-gravimetric data were used at five heating rates: 2°C min?1, 5°C min?1, 10°C min?1, 15°C min?1 and 20°C min?1. As the most suitable mechanism, the three-step mechanism containing the intermediate degradation step was chosen. This selection was supported by experimental results from the 13C NMR analysis of solid residues prepared at the key temperatures within the range of 230–500°C. The progress of mass fraction values of each component in this mechanism was simulated. Conclusions from the simulation were confronted with experimental results from the 13C NMR. 相似文献
8.
In
this research, thermal characterization and kinetics of Karakus crude oil
in the presence of limestone matrix is investigated. Thermogravimetry (TG/DTG)
is used to characterize the crude oil in the temperature range of 20-900°C,
at 10°C min -1 heating rate using air
flow rate of 20 mL min -1. In combustion
with air, three distinct reaction regions were identified known as low temperature
oxidation (LTO), fuel deposition (FD) and high temperature oxidation (HTO).
Five different kinetic methods used to analyze the TG/DTG data to identify
reaction parameters as activation energy and Arrhenius constant. On the other
hand different f(α) models from literature
were also applied to make comparison. It was observed that high temperature
oxidation temperature (HTO) activation energy of Karakus crude oil is varied
between 54.1 and 86.1 kJ mol -1, while low
temperature oxidation temperature (LTO) is varied between 6.9 and 8.9 kJ mol -1. 相似文献
9.
Marcelo Kobelnilk Gustavo Guadagnucci Fontanari Douglas Lopes Cassimiro Clóvis Augusto Ribeiro Marisa Spirandeli Crespi 《Journal of Thermal Analysis and Calorimetry》2014,115(3):2045-2052
Coffee seeds are a source for obtaining oil which is used in the candy, soluble coffee, and cosmetics industries. The main purpose of this study was the investigation of the lipid profile and thermal behavior of the roasted and in nature coffee oil of Arabica and Robusta species, using thermogravimetry, differential thermal analysis, derivative thermogravimetry, differential scanning calorimetry (DSC), and modulated DSC. Details concerning the thermal decomposition as well as data of the kinetic parameters have been described here. The kinetic studies were evaluated from several heating rates with a sample mass of 10 mg in open crucible under nitrogen atmospheres. The obtained data were evaluated with the isoconversional kinetic method, where the values of activation energy (E a/kJ mol?1) were evaluated in function of the conversion degree (α). In addition, this oil was evaluated by modulated DSC from 25 to ?60 °C, where the transition phase behavior was verified. 相似文献
10.
Heating rate effect on the DSC kinetics of oil shales 总被引:1,自引:0,他引:1
M. V. Kök 《Journal of Thermal Analysis and Calorimetry》2007,90(3):817-821
This research was aimed to investigate the combustion and kinetics of oil shale samples (Mengen and Himmetoğlu) by differential
scanning calorimetry (DSC). Experiments were performed in air atmosphere up to 600°C at five different heating rates. The
DSC curves clearly demonstrate distinct reaction regions in the oil shale samples studied. Reaction intervals, peak and burn-out
temperatures of the oil shale samples are also determined. Arrhenius kinetic method was used to analyze the DSC data and it
was observed that the activation energies of the samples are varied in the range of 22.4–127.3 kJ mol−1 depending on the oil shale type and heating rate. 相似文献
11.
Pyrolysis of a wood chips mixture and main wood compounds such as hemicellulose, cellulose and lignin was investigated by
thermogravimetry. The investigation was carried out in inert nitrogen atmosphere with temperatures ranging from 20°C to 900°C
for four heating rates: 2 K min−1, 5 K min−1, 10 K min−1, and 15 K min−1. Hemicellulose, cellulose, and lignin were used as the main compounds of biomass. TGA and DTG temperature dependencies were
evaluated. Decomposition processes proceed in three main stages: water evaporation, and active and passive pyrolysis. The
decomposition of hemicellulose and cellulose takes place in the temperature range of 200–380°C and 250–380°C, while lignin
decomposition seems to be ranging from 180°C up to 900°C. The isoconversional method was used to determine kinetic parameters
such as activation energy and pre-exponential factor mainly in the stage of active pyrolysis and partially in the passive
stage. It was found that, at the end of the decomposition process, the value of activation energy decreases. Reaction order
does not have a significant influence on the process because of the high value of the pre-exponential factor. Obtained kinetic
parameters were used to calculate simulated decompositions at different heating rates. Experimental data compared with the
simulation ones were in good accordance at all heating rates. From the pyrolysis of hemicellulose, cellulose, and lignin it
is clear that the decomposition process of wood is dependent on the composition and concentration of the main compounds. 相似文献
12.
M. V. Kök 《Journal of Thermal Analysis and Calorimetry》2005,79(1):175-180
Differential scanning calorimetry (DSC) and thermogravimetry (TG/DTG) has been used to obtain information on the temperature-controlled combustion characteristics of seventeen coals of different origin from Thrace basin of Turkey. Experiments were performed in air atmosphere up to 600°C at a heating rate of 10°C min-1. The DSC/TG curves clearly demonstrate distinct transitional stages in the entire coal samples studied. Reaction intervals, peak and burn-out temperatures of the coal samples are also determined. Two different kinetic methods known as, Arrhenius and Coats-Redfern, were used to analyze the kinetic data and the results are discussed. 相似文献
13.
Adriana Fuliaş Titus Vlase Gabriela Vlase Nicolae Doca 《Journal of Thermal Analysis and Calorimetry》2010,99(3):987-992
The thermoanalytical curves (TA), i.e. TG, DTG and DTA for pure cephalexin and its mixtures with talc, magnesium stearate,
starch and microcrystalline cellulose, respectively, were drawn up in air and nitrogen at a heating rate of 10 °C min−1. The thermal degradation was discussed on the basis of EGA data obtained for a heating rate of 20 °C min−1. Until 250 °C, the TA curves are similar for all mixtures, up this some peculiarities depending on the additive appears.
These certify that between the pure cephalosporin and the excipients do not exists any interaction until 250 °C. A kinetic
analysis was performed using the TG/DTG data in air for the first step of cephalexin decomposition at four heating rates:
5, 7, 10 and 12 °C min−1. The data processing strategy was based on a differential method (Friedman), an integral method (Flynn–Wall–Ozawa) and a
nonparametric kinetic method (NPK). This last one allowed an intrinsic separation of the temperature, respective conversion
dependence on the reaction rate and less speculative discussions on the kinetic model. All there methods had furnished very
near values of the activation energy, this being an argument for a single thermooxidative degradation at the beginning (192–200 °C). 相似文献
14.
The heating rate effect on the thermal behavior of clays from Arumetsa and Kunda deposits (Estonia) and an illitic clay from Füzérradvány (Hungary) was studied. Experiments were carried out under dynamic heating condition up to 1050 °C at the heating rates of 1.25, 2.5, 5 and 10 °C min?1 in a stream of gas mixture containing 79 % of Ar and 21 % of O2 with Setaram Labsys 1600 analyzer. Two different ashes were used as additives: the electrostatic precipitator ash from the first field and the cyclone ash formed, respectively, at circulating fluidized bed combustion (temperatures 750–830 °C) and pulverized firing (temperatures 1200–1400 °C) of Estonian oil shale at Estonian Power Plant. For calculation of kinetic parameters, the TG data were processed by the differential isoconversional Friedman method. The results of thermal analysis and the variation of the value of activation energy E along the reaction progress α indicated the complex character of decomposition of clays and their blends with Estonian oil shale ashes, and the certain differences in thermal behavior of different clays depending on their origin. 相似文献
15.
A kinetic study on the thermal behaviour of chitosan 总被引:1,自引:0,他引:1
F. A. López A. L. R. Mercê F. J. Alguacil A. López-Delgado 《Journal of Thermal Analysis and Calorimetry》2008,91(2):633-639
The thermal behaviour of chitosan was studied by means of thermogravimetry, mass spectrometry and infrared spectrometry. Kinetic
parameters were obtained by advanced kinetic evaluation (differential isoconversional analysis) from DSC curves, in non-isothermal
conditions, at several heating rates, between 5 and 30°C min−1. The results showed that the decomposition of chitosan does not follow a single mechanism because both the activation energy
and the pre-exponential factor are not constant during the course of the reaction. A comparison with the results obtained
by applying different conventional calculating methods is also shown. 相似文献
16.
Research of thermal decomposition kinetic characteristic of emulsion explosive base containing Fe and Mn elements 总被引:1,自引:0,他引:1
X. H. Wang X. J. Li H. H. Yan Y. D. Qu G. L. Sun X. H. Xie Y. J. Zhang 《Journal of Thermal Analysis and Calorimetry》2008,91(2):545-550
The kinetic characteristic of thermal decomposition of the Emulsion Explosive Base Containing Fe and Mn elements (EEBCFM)
which was used to prepare nano-MnFe2O4 particles via detonation method was investigated by means of non-isothermal DSC and TG methods at various heating rates of
2.5, 5 and 7.5°C min−1respectively under the atmosphere of dynamic air from room temperature to 400°C.
The results indicated that the EEBCFM was sensitive to temperature, especially to heating rate and could decompose at the
temperature up to 60°C. The maximum speed of decomposition (dα/dT)m at the heating rate of 5 and 7.5°C min−1 was more than 10 times of that at 2.5°C min−1 and nearly 10 times of that of the second-category coal mine permitted commercial emulsion explosive (SCPCEE). The plenty
of metal ions could seriously reduce the thermal stability of emulsion explosive, and the decomposition reaction in the conversion
degree range of 0.0∼0.6 was most probably controlled by nucleation and growth mechanism and the mechanism function could be
described with Avrami-Erofeev equation with n=2. When the fractional extent of reaction α>0.6, the combustion of oil phase primarily controlled the decomposition reaction. 相似文献
17.
Simon H. Vincze Z. Marthi K. Lévai G. Pokol G. Fogassy E. Kozma D. 《Journal of Thermal Analysis and Calorimetry》2004,75(3):787-793
A non-isothermal experimental study using thermogravimetry (TG) and differential scanning calorimetry (DSC) was conducted
for investigation the oxidation reactivity of natural phosphate and its demineralised products. The analyses were carried
out in oxygen atmosphere and at different heating rate (5, 10, 20, 30, 50, 60°C min-1) up to 1000°C. The results indicated that the material washed with HCl from the original phosphate, mainly apatite and carbonates
of calcium and magnesium, as well as with HCl/HF, silicates minreals, had an inhibition effect during oxidation reactions
of organic material. The increase of the heating rate shifted the reactions to higher temperatures. In addition, kinetic parameters
were determined by assuming a single first-order kinetic model, using the Coats-Redfern method. The influences of demineralization
process of natural phosphate and the heating rate were examined and discussed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
18.
Yi-Bo Li Jin-Zhou Zhao Wan-Fen Pu Hu Jia Huan Peng Dong Zhong Sheng-Kui Wang 《Journal of Thermal Analysis and Calorimetry》2013,113(2):579-587
This research aimed at the investigation of the effect of different metallic additive on the combustion and kinetic behavior of crude oil. For this purpose, the thermal behavior of the oil-only and oil–metallic salts mixtures were studies by the thermogravimetry (TG)/derivative thermogravimetry and differential scanning calorimetry (DSC) on heating rate at 10 °C min?1. The result shows that Dagang crude oil exhibited apparent low temperature oxidation (LTO), fuel deposition, and high temperature oxidation processes. With the addition of metallic salts, the LTO process has been shortened and samples added CuSO4, CrCl3·6H2O, and AlCl3·6H2O achieved a much lower peak temperature than that of oil. Based on the Arrhenius model, metallic additives were proven to have obvious influence on the combustion activation energy. And, by comprehensive analysis of TG/DSC profile and activation energy, ZnSO4 exhibited a positive influence on light crude oil combustion during the high pressure air injection process. 相似文献
19.
In the present work, kinetics of thermal decomposition of 2,2-dinitropropyl acrylate–styrene copolymer (DNPA/St) and 2,2-dinitropropyl acrylate–vinyl acetate copolymer (DNPA/VAc) was investigated by differential scanning calorimetry (DSC). The influence of the heating rate (5, 10, 15, and 20 °C min?1) on the DSC behavior of the copolymer was verified. The results showed that, as the heating rate was increased, decomposition temperature of the copolymer was increased. Also, the kinetic parameters such as activation energy and frequency factor of the copolymer were obtained from the DSC data by the isoconversional methods proposed by Kissinger–Akahira–Sunose (KAS) and Flynn–Wall–Ozawa (FWO). Average activation energy obtained by KAS and FWO methods for the thermal decomposition reaction of DNPA/St and DNPA/VAc are 157.38 ± 0.27 and 147.67 ± 0.57 kJ mol?1, respectively. The rate constants for thermal decomposition calculated from the activation parameters showed the structural dependency. The relative stability of two copolymers under 50 °C was in this order: DNPA/St > DNPA/VAc. The results of thermogravimetry (TG) analysis revealed that the main mass changes for DNPA/St and DNPA/VAc occurred in the temperature ranges of 200–270 °C. The DSC-FTIR analysis of DNPA/St indicates that the band intensity of nitro and other groups increased haphazardly from 230 °C due to thermal decomposition. 相似文献
20.
Yingli Wang YuYing Zhao Yongquan Zuo Liping Chang 《Journal of Thermal Analysis and Calorimetry》2013,111(3):1939-1945
Eight kinds of Radix Codonopsis (RC) from different origins in China were selected as the experimental samples fort his study. Their pyrolysis processes were researched by the method of thermogravimetry analysis, in which the heating course was set in the ways of programming temperature from room temperature to 500 °C at different heating rates. Research results show that the process in the heating period of RC includes three stages: water loss, fast pyrolysis, and medium rate decomposition. For cultivated RC, the average initial decomposition temperature in the fast pyrolysis stage is 115 °C, whereas the peak temperature of the fast pyrolysis stage is changed from 189 to 225 °C, in which stage the alcohol-soluble substances are mainly decomposed. It is required to control the operational temperatures of drying and concocting processes according to initial decomposition temperature. Kissinger–Akahira–Sunose model can be used to describe the process mechanism of RC pyrolysis, and the kinetic analyses based on the fast pyrolysis stage thermogravimetric data show that the activation energies change from 141 to 207 kJ mol?1 for cultivated RC samples and 122 to 131 kJ mol?1for wild RC samples. The alcohol-soluble extract (ASE) content of wild RC samples is lower than that of cultivated RC samples; their thermal stability is also relatively poor. 相似文献