Gravimetric dynamic vapor-sorption apparatus with mass spectrometer coupling

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A gravimetric, dynamic vapor sorption device with mass spectrometry coupling (DVS-MS) makes it possible to record a mass change signal in combination with quantitative information regarding the vapor-gas composition. The possibility to work at temperatures up to 300 °C as well as with water vapor, organic vapors, other gases and variable vapor-gas mixtures is especially necessary for the following investigations: Investigation of co-adsorption processes; studies on the behavior of electrode materials at elevated temperature and high relative humidity (85 °C; 85 % RH), insights into catalytic and non-catalytic processes in which organic vapors are used, and investigations to derive material properties. While several departments at the TU Darmstadt operate thermal analyzers, in some cases also with mass spectrometry coupling, a setup is still missing that can operate under parallel water vapor and organic vapor composition of the gas phase and that, in particular, meets the requirements regarding the avoidance of condensation at high relative humidities and the long-term stable quantitative measurement of the vapor-gas composition. A central requirement in this context is operation under technically relevant operating conditions. Only in this way insights into the behavior of the sample close to conditions of the applications can be obtained and thus important structure-activity relationships be derived. For example, membrane electrode assemblies (MEAs) of PEM fuel cells can be investigated with respect to water management under realistic operating conditions. This is similar for catalytically active materials whose activity and selectivity patterns can be influenced by water as a co-feed. Due to the planned application scenarios of the measurement setup (DVS-MS), a flexible dosing of steam-gas mixtures is necessary. Furthermore, a measurement of the vapor-gas composition with the online mass spectrometer as close to the sample as possible is aimed at in order to minimize the risk of potential measurement artifacts due to condensation phenomena.