The non-parametric kinetics (NPK) method has been recently developed for the kinetic treatment of thermoanalytical data. The
most significant feature of this method is its ability to provide information about the reaction kinetics without any assumptions
either about the functionality of the reaction rate with the degree of conversion or the temperature. This paper presents
the results of the application of the method to adiabatic calorimetry. Some data have been obtained by numerical simulation,
but also the thermal decomposition of DTBP, a well known first order reaction, has been studied, being the obtained results
in good agreement with literature.
Authors:A. Aboulkas, K. El Harfi, A. El Bouadili, M. Chanâa, and A. Mokhlisse
The pyrolysis of oil shale and plastic wastes is being presently considered as an alternative means of partial substitution
of fossil fuels to generate the necessary energy to supply the increasing energy demand and as well as new technology to reduce
the negative environment of plastic wastes. However, Knowledge of pyrolysis kinetics is of great imponrtance for the design
and simulation of the reactor and in order to establish the optimum process conditions.
In this study, the thermal decomposition of polypropylene, oil shale and their mixture was studied by TG under a nitrogen
atmosphere. Experiments were carried out for various heating rates (2, 10, 20, 50 K min−1) in the temperature range 300–1273 K. The values of the obtained activation energies are 207 kJ mol−1 for polyethylene, 57 kJ mol−1 for the organic matter contained in the oil shale and 174 kJ mol−1 for the mixture. The results indicate that the decomposition of these materials depends on the heating rate, and that polypropylene
acts as catalyst in the degradation of the oil shale in the mixture.
Thermal analysis is increasingly being used to obtain kinetic data relating to sample decomposition. In this research differential
scanning calorimeter (DSC) was used to determine the combustion kinetics of three (an, Himmetoglu and Mengen) oil shale samples
by ASTM and Roger & Morris methods. On DSC curves two reaction regions were observed on oil shale sample studied except an
oil shale. In DSC experiments higher heating rates resulted in higher reaction temperatures and higher heat of reactions.
Distinguishing peaks shifted to higher temperatures with an increase in heating rate. Three different kinetic models (ASTM
I-II and Rogers & Morris) were used to determine the kinetic parameters of the oil shale samples studied. Activation energies
were in the range of 131.8-185.3 kJ mol-1 for ASTM methods and 18.5-48.8 kJ mol-1 for Rogers & Morris method.
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 20-900C,
at 10C 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.
The kinetics and mechanism of the dehydration and decomposition of heteropolyacids of molybdenum, tungsten and vanadium (H3+xYx+M12O40mH2O;
Y=Si, P; M=Mo, W) were studied. The data obtained on the dehydration kinetic parameters correlate with the expected structures,
of these crystal hydrates, the IR data and X-ray phase analysis.
Cadmium carbonate used in the study was prepared from cadmium chloride, ammonium carbonate and ammonia. The X-ray powder diffraction,
infrared spectral and chemical analysis conducted on the product show that the sample is of analytically acceptable purity.
The thermal decomposition kinetics of cadmium carbonate was then studied by using the isothermal thermogravimetric method
under a flow of dry nitrogen gas. The decomposition kinetics is best described by a two-dimensional phase boundary reaction
mechanism (R2). An activation energy (Ea) of 135.006 kJ·mol−1 and natural logarithm of the frequency factor (lnZ) of 16.754 were obtained in the range of 9 temperatures (400, 390, 380, 370, 360, 350, 340, 330 and 320°C).
Mechanism of the processes in condensed phase are very often unknown or too complicated to be characterised by a simple kinetic
model. They tend to occur in multiple steps that have different rates. To describe their kinetics, the single-step kinetics
approximation is often applied which resides in substituting a generally complex set of kinetic equations by the sole single-step
kinetics equation. The main contribution of the single-step kinetics approximation is that it enables a mathematical description
of the kinetics of solid-state reactions without a deeper insight into their mechanism. The single-step kinetics approximation
is based on the assumption that the temperature and conversion functions are separable. In the paper, some consequences originating
from ignoring the function separability are discussed.
Thermal decomposition of different inorganic sulphates are presented. A number of techniques, but mainly TG and DTA, are used to prove the mechanism and kinetics of CaSO4, BaSO4, FeSO4·xH2O, Al2(SO4)3·xH2O under various gas atmospheres. It is shown how the partial pressure of gas components and heating rate may effect the mechanism and kinetic parameters. There are also examples on the effects of some additives and initial treatment on the thermal processes.
On the base of the results obtained some recommendations are given concerning the precautions to be taken into account in the thermal decomposition studies and the sulphur recovering.