Authors:J. Liu, D. He, L. Xu, H. Yang, and Q. Wang
The combustion behavior of Shuangya Mountain (SYM) coal dust has been investigated by means of TG in this paper. The reaction fraction can be obtained from isothermal TG data. The regressions of g(), an integral function of
vs. t for different reaction mechanisms were performed. The mechanism of nucleation and nuclei growth is determined as the controlling step of the coal dust combustion reaction by the correlation coefficient of the regression, and the kinetic equation of the SYM coal dust combustion reaction has been established.
Authors:N. Mallikarjuna, A. Lagashetty, and A. Venkataraman
Cobalt ferrite was synthesised by the thermal decomposition of a citrate precursor through a novel self-propagating combustion
reaction (SPCR) and the progress of this reaction is explained. Cobalt ferrite obtained by this reaction is compared with
the products obtained by heat treatment of the citrate complex. The thermal behaviour and structures of the precursor, the
synthesised ferrite, and the other decomposition products are investigated.
Authors:Everton Fernando Zanoelo and Cristina Benincá
and k 2 is directly proportional to the rate constant of the slow combustionreaction of 5-CQA, as determined by Eq. 14 . This ratio reveals that the activation energy of the investigated reaction of oxidation is close to 77046 J mol −1 .
Authors:L. Peng, X. Jiangjun, M. Fangquan, L. Xi, and Z. Chaocan
The standard molar enthalpy of combustion of cholesterol was measured at constant volume. According to value of ΔrUmθ(−14358.4±20.65 kJ mol−1), ΔrHmθ(−14385.7 kJ mol−1) of combustion reaction and ΔfHmθ(2812.9 kJ mol−1) of cholesterol were obtained from the reaction equation. The enthalpy of combustion reaction of cholesterol was also estimated
by the average bond enthalpies. By design of a thermo-chemical recycle, the enthalpy of combustion of cholesterol were calculated
between 283.15∼373.15 K. Besides, molar enthalpy and entropy of fusion of cholesterol was obtained by DSC technique.
Authors:R. da Costa Lima, Magali Pinho, and T. Ogasawara
The focus of this work is the use of thermal analyses and Fourier Transform Infrared Spectroscopy (FTIR) for characterization
of the gel decomposition, resulting from the formation of Y-barium hexaferrite substituted by Zn ions (Zn-Y-barium hexaferrite).
Samples with Ba2Zn2Fe12O22 composition were synthesized by the citrate auto-combustion method. During the TG experiments the highest mass loss was attributed
to citrate decomposition owing to the self-combustion reaction, confirmed by the disappearance of –OH band, and the drastic
decrease of –CO2−and –NO3− bands. Zn substitution resulted in an X-band microwave absorber material.
Authors:S. Ramanathan, M. Kakade, P. Ravindran, B. Kalekar, K. Chetty, and A. Tyagi
Precursor powders for
yttrium aluminum garnet (YAG) were synthesized by solution combustion reactions
(nitrate–glycine reaction with stoichiometric and sub-stoichiometric
amount of fuel) and simple decomposition of nitrate solution. The TG-DTA,
FTIR and XRD analyses of the precursors and the typical heat-treated samples
were carried out to understand the processes occurring at various stages during
heating to obtain phase pure YAG. Precursors from all the reactions exhibited
dehydration of adsorbed moisture in the temperature range of 30 to 300°C.
The precursor from nitrate–glycine reaction with stoichiometric amount
of fuel (precursor- A) contained entrapped oxides of carbon (CO and CO2)
and a carbonaceous contaminant. It exhibited burning away of the carbonaceous
contaminant and crystallization to pure YAG accompanied by loss of oxides
of carbon in the temperature ranges of 400 to 600 and 880 to 1050°C. The
precursor from simple decomposition of nitrates (precursor-B) exhibited denitration
cum dehydroxylation and crystallization in the temperature ranges of 300 to
600 and 850 to 1050°C. The precursor from nitrate–glycine reaction
with sub-stoichiometric amount of fuel (precursor-C) contained entrapped carbon
dioxide and exhibited its release during crystallization in the temperature
range of 850 to 1050°C. This study established that, in case of metal
nitrate–glycine combustion reactions, crystalline YAG formation occurs
from an amorphous compound with entrapped oxides of carbon. In case of simple
decomposition of metal nitrates, formation of crystalline YAG occurs from
an amorphous oxide intermediate.
In this study, four oil-shale samples (Niğde-Ulukışla) excavated from Central Anatolia Turkey were analyzed where this region
is believed to have a high potential of oil in its shale rich outcrops. The samples (∼40 g) were combusted at 50 psi gas injection
pressure, at an air injection rate of 1.5 L min−1 in a combustion-reaction cell. All the experiments were conducted up to 600°C. The percentages of oxygen consumption and
carbon monoxide and carbon dioxide production were obtained instantaneously with respect to time. The combustion periods and
relative reaction rates were determined by examining the effluent gas concentration peaks. Activation energies of the samples
were determined using Weijdema’s approach. It was observed that the activation energies of the samples are varied between
22–103 kJ mol−1.
Authors:B. Zapata, J. Balmaseda, E. Fregoso-Israel, and E. Torres-García
Thermal degradation of orange peel was studied in dynamic air atmosphere by means of simultaneous TG-DSC and TG-FTIR analysis.
According to the obtained thermal profiles, the orange peel degradation occurred in at least three steps associated with its
three main components (hemicellulose, cellulose and lignin). The volatiles compounds evolved out at 150–400 °C and the gas
products were mainly CO2, CO, and CH4. A mixture of acids, aldehydes or ketones C=O, alkanes C–C, ethers C–O–C and H2O was also detected. The Eα on α dependence reveled the existence of different and simultaneous processes suggesting that the combustion reaction is
controlled by oxygen accessibility, motivated by the high evolution low-molecular-mass gases and volatile organic compounds.
These results could explain the non-autocatalytic character of the reactions during the decomposition process.
Authors:Robert Ianoş, Ioan Lazău, and Cornelia Păcurariu
The reactivity of LiNO3 and Al(NO3)3 with respect to urea and β-alanine was investigated. Experimental results proved that β-alanine is a more suitable fuel for
LiNO3, whereas urea seems to be more adequate for Al(NO3)3. Based on the different metal nitrate/fuel mixture reactivity, nanocrystalline γ-LiAlO2 powders were prepared by solution combustion synthesis using a fuel mixture of urea and β-alanine. This fuel mixture yielded
single-phase nanocrystalline γ-LiAlO2 (32.6 nm) directly from the combustion reaction. The resulted powder had a specific surface area of 3.2 m2/g and no supplementary annealing was required. On the other hand, pure γ-LiAlO2 could not be obtained by using a single fuel (urea, β-alanine) unless annealing at 900 °C for 1 h was performed.
In this research, the relationship between particle size and combustion kinetics and combustion properties of lignite samples
was examined by utilizing the thermogravimetric (TG/DTG) and differential thermal analysis (DTA) techniques. The lignite samples
separated into different size fractions were subjected to non-isothermal thermogravimetric analysis between ambient and 900�C
in the presence of 50 mL min−1 air flow rate. Activation energy (E) and Arrhenius constant (Ar) of combustion reaction of each size was evaluated by applying Arrhenius kinetic model to the resulting data. Combustion
properties of the samples were interpreted by careful examination of the curves. The apparent activation energies in major
combustion region were calculated as 41.03 and 53.11 kJ mol−1 for the largest size (−2360+2000 μm) and the finest size (−38 μm), respectively.