Thermal Analysis Instrument coupled to a Mass Spectrometer

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The procurement of a setup consisting of a Simultaneous Thermal Analysis (STA) coupled to a Mass Spectrometer (MS) allows the acquisition of a mass change signal in combination with quantitative information about the exhaust gas composition. In this sense, the possibility to work at temperatures up to 1600 °C and to perform oxygen-sensitive measurements is especially necessary for the following studies: Derivation of material properties; studies of synthesis steps such as pyrolysis, selective desorption, carbon activation, reduction or oxidation; insights into changes during non-catalytic and catalytic processes. Although different groups at the TU Darmstadt already use this technique, there is currently no setup that can cover the temperature range up to 1600 °C while meeting the special requirements of an oxygen-free operation and long-term stable quantitative mass spectrometry measurements of the evolved gas. Especially for the pyrolysis of polymers at temperatures up to 1600 °C, the smallest amounts of residual oxygen are critical. A distorted picture can also be obtained when investigating the desorption behavior of surface functional groups, particularly for materials exhibiting only a small degree of functionalization. Likewise, residual oxygen can falsify investigations on the long-term stability of ionic liquids under inert gas. Until now, the inherently large dead volume of the thermogravimetric apparatus and the resulting unknown long purging time has been the major problem. However, by monitoring the oxygen content during the purging step of the apparatus ensures the subsequent oxygen-free operation without the contamination of the mass spectrometer, e.g. with water. The use of an automatic sample changer is furthermore not only necessary for an efficient use of the instrument and maximum throughput, but also allows the automated analysis of calibration substances during the measurement campaign. Due to the planned application of complex temperature and gas programs, a good software coupling of thermogravimetric and mass spectrometry analysis is necessary.