With the PulseTA® technique a precisely defined quantity of gas is injected into the purge gas of the thermobalance (TGA) or the simultaneous thermal analysis instrument (STA).
This allows for a broader spectrum of measuring possibilities:
1) Injection of a gas which reacts chemically with solids
Changes in the solid phase and gas composition resulting from the injected pulse can be investigated.
Reduction, oxidation, and catalytic processes between solid catalyst and gaseous reactants can be investigated at desired temperatures.
Very slight processes in the reaction can be monitored, since gas-solid reactions occur only during the duration of a pulse when PulseTA® is used.
2) Injection of gas which adsorbs on the solid
The capability of simultaneously monitoring changes in mass and thermal effects allows PulseTA® to be applied in the investigation of adsorption phenomena occurring under atmospheric pressure at specific temperatures (chemisorption / physisorption processes).
3) Injection of inert gas
Injection of a known amount of gas into the carrier gas stream of the system during TA-EGA measurements allows for a more reliable quantitative calibration of the MS and FT-IR signals.
The calibration is achieved by determining the relationship between the amount of the injected gas and the intensity of the MS and/or FT-IR signal(s).
Sensitivities of less than 0.01 wt% can be easily achieved for the evolved species.
The humidity generator produces defined relative humidity by mixing wet and dry gas flows. A minimum humidity of 5% relative humidity at approx. 30°C (0.2% absolute humidity) can be achieved. The maximum humidity amounts to 90% relative humidity at 70°C (30% absolute humidity). Using a humidity generator requires a water vapor furnace for concentrations of ≥ 2% absolute humidity (100% relative humidity at 15°C). For low humidity (≤ 2%) any furnace can be used; however, condensation must be avoided. Humid atmosphere concentration is software-controlled (programmable ramps/steps). The system allows for easy refill while a measurement is running.
Water Vapor Generator
The water vapor generator produces steam by evaporating liquid water. Absolute humidity concentrations of approx. 5% to 100% can be achieved. Dilution by inert gas and evacuation prior to the measurement are possible. The water vapor generator requires a water vapor furnace.
Oxygen Trap System (OTS®)
The OTS® oxygen trap system for the STA 449 F1/F3 Jupiter® and DSC 404 F1/F3 Pegasus® systems removes traces of residual oxygen in the gas atmosphere inside the instrument. A residual oxygen content of <1ppm can be achieved. Thanks to the getter ring, it is possible to almost entirely eliminate the residual oxygen after evacuation. Such low oxygen concentrations cannot be achieved unless the instrument is vacuum-tight and equipped with an evacuation system.
Residual O2 level is a function of:
Vacuum tightness of the instrument
Desorption of O2 from the walls
Vacuum tightness of the gas supply
Purity of the purge gas
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