How To Find Activation Energy for Single-Step Decomposition Process From TG experiments
Required:
NETZSCH Proteus Analysis software version 9.10 (or higher)
Kinetics Lite option
Introduction
For kinetic analysis it is necessary to open in NETZSCH Protes Analysis software at least 3 experimental curves measured at different temperature conditions, more measurements are recommended. Usually, segments with different heating rates or segments with different isothermal conditions are used for kinetic analysis. For Thermogravimetric measured data it is possible also use the experimental curve with connected segments having heating and isothermal segments together.
This example presents the first decomposition step of Calcium Oxalate Monohydrate, where step with water release is analyzed as the single-step reaction.
Importing TG Data from NETZSCH Proteus Analysis
- In NETZSCH Protes Analysis software open at least 3 experimental thermogravimetry curves measured at different temperature conditions
- For each experimental curve evaluate the mass loss for the temperature (or time) range of interest. The evaluation ranges can be different for different curves.
- Select curves with mass change evaluation (click and ctrl+click on each curve or single click on TG axis):
Figure 1. Proteus Analysis software with TG data for kinetic analysis
4. In NETZSCH Protes Analysis select Kinetics Lite from Extras menu Item.
Figure 2. Selection of Kinetic Lite Option in NETZSCH Proteus Analysis software
Result: Kinetics Lite is started, where selected curves are automatically loaded from Proteus Analysis into Kinetics Lite. Only selected ranges are imported, file names can be seen in Legend if File Name is selected in View ribbon.
Figure 3. Experimental curves are automatically loaded from Proteus Analysis into Kinetics Lite.
5. In Project Panel click on Add New to create single-step kinetic model.
Result: new single-step kinetic model is created. The reaction type is found automatically, for decomposition it is usually n-th order reaction, however, decomposition with autocatalysis sometimes is present.
In the Properties panel you can find kinetic equation and kinetic parameters, including activation energy in kJ/mol. In the bottom of Properties Panel the fit quality R² can be found as well as the possibility to export kinetic equation with kinetic parameters to external txt file.
Figure 4. Experimental data (symbols) and simulated curves for single-step kinetic model.