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Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC)

The materials characterization laboratory is equipped with a Thermogravimetric Analysis and Simultaneous Difference Thermal Analysis (TGA/SDTA) unit (Figure 1). The system includes a METTLER TGA/SDTA851e thermobalance and its STARe software.

In thermogravimetry (TGA), weight changes of a substance that occur during a controlled temperature program and in a defined gas atmosphere are measured. In the Difference Thermal Analysis (DTA), temperature changes of a substance (in relation to a reference temperature) that occur during a controlled temperature program and in a defined gas atmosphere are measured.

Figure 1: Systems for Thermogravimetric Analysis and a Differential Scanning Calorimetry.

At CAMMP, the TGA/SDTA unit is used to measure weight changes of zeolite and zeotype samples (Figure 2). Moisture and organic contents in a zeolite sample can be determined in a single experiment.

Figure 2: TGA patterns for calcined zeolite NH4-Beta (Si/Al=12.5) after contact with (a) saturated solution of (R,R)-(+)-hydrobenzoin in water and (b) saturated solution of racemic hydrobenzoin in water. Since zeolite Beta adsorbed more from the racemic mixture (weight loss of 8.9 with an error of 0.2% in the 220-620 C temperature range) than from single enantiomer solution (weight loss of 5.9 with an error of 0.3% in the 220-620 C temperature range) and the solution concentration and ratio of solution to solid adsorbent were the same in these experiments, these adsorption results suggest that some pores in zeolite Beta are not accessible to both enantiomers of hydrobenzoin, and the enantiomorphs of polymorph A of zeolite Beta can discriminate the enantiomers of hydrobenzoin (Manning et al., Proceedings: 14th International Zeolite Conference, 2004, 1957-1960).

The materials characterization laboratory is also equipped with a Differential Scanning Calorimetry (DSC) unit. The system includes a METTLER DSC822e model thermal analyzer and its STARe software (also in Figure 1).

The thermal analyzer is an instrument for performing dynamic differential calorimetry measurements and is based on the well-proven Boersma or heat flux principle. The amount of energy (heat) absorbed or released by a substance, which occurs during a controlled temperature program and in a defined gas atmosphere, is measured.

At CAMMP, the DSC unit is used jointly with thermogravimetric analysis (TGA) to measure heat and temperature associated with the evaporation of moisture and organic molecules from a zeolite sample (Figure 3).

Figure 3: DSC patterns for (a) as received and (b) purified (S,S)-(-)-hydrobenzoin. The lower melting point (139.1 with an error 0.3 C) and broader DSC peak of as received hydrobenzoin indicate that the sample contains impurities. Multiple recrystallization from ethanol followed by drying in dry nitrogen at 100 C increased purity of hydrobenzoin, as indicated by a sharper DSC peak and the melting point (146.2 with an error of 0.3 C) identical within experimental error to the melting point of pure hydrobenzoin (146 C) (Karahan, Ph.D. Thesis, 2003, Northeastern University, Boston, MA, USA).