Technical comments
Prediction of the Progress of Solid-State Reactions under Different Tempreature Modes
Using a computational method (AKTS-TA-Software) for solid-state kinetic analysis, the calculations of the progress of solid-state reactions were achieved employing temperature conditions different from those at which the experiments were carried out. The prediction of the solid-state reaction extent is illustrated by the results obtained during decomposition of hydromagnesite (component of some pharmaceuticals) …
Computational aspects of kinetic analysis: Part A: The ICTAC kinetics project-data, methods and results
Part A of this series of papers (Parts B to E follow) presents the data and methods used, as well as the results obtained by participants in the ICTAC Kinetics Project. The isothermal and non-isothermal data sets provided were based on a hypothetical simulated process as well as on some actual experimental results for the thermal decompositions of ammonium perchlorate and calcium carbonate. The participants applied a variety of computational methods. Isoconversional and multi-heating rate methods were particularly successful in correctly describing the multi-step kinetics used in the simulated data …
Computational aspects of kinetic analysis.: Part E: The ICTAC Kinetics Project—numerical techniques and kinetics of solid state processes
The hyphenated thermal analysis-mass spectrometry technique (TA-MS) was applied for the investigation of the thermal behavior of reference and aged parchment samples. The kinetic parameters of the process were calculated independently from all recorded TA and MS signals. The kinetic analysis showed the distinct dependence of the activation energy on the reaction progress. Such behavior is characteristic for the multistage mechanism of the reaction …
Influence of mass transfer on interaction between thermoanalytical and mass spectrometric curves measured in combined thermoanalyser-mass spectrometer systems
The convective and diffusional mass transfer occurring in combined thermoanalyser-mass spectrometer systems can cause significant deviation between measured thermoanalytical and mass spectrometric curves. Based on experimental studies of the decomposition of CaCO3, a model has been developed which allows to interrelate the thermoanalytical (DTG) and mass spectrometric curves and provides a criterion defining under which conditions (carrier gas-flow rate and diffusivity of evolved gas) the disguising mass-transfer influences can be neglected. The criterion relates the total residence time τtot of the gas in the experimental system to the characteristic time tN of the gravimetrically recorded decomposition process and allows to quantify the agreement between the thermoanalytical and mass spectrometric curves …
Influence of experimental conditions on the kinetic parameters of gas-solid reactions—parametric sensitivity of thermal analysis
The influence of experimental conditions on the kinetic parameters of gas-solid reactions has been investigated using the reduction of nickel oxide by hydrogen as a model reaction. The experimental parameter studied were heating rate, sample mass, total gas flow and hydrogen concentration. For arbitrarily chosen “standard conditions” the kinetic parameters best describing the course of the reaction were calculated using the global cruves analysis method. Experiments were carried out with different heating reates, in the range 1.3-10.6 K min-1. Twenty two kinetic models of solid-state reactions proposed in the literature were tested using numeric integration methods …