Physisorption with different gases using nitrogen cooling: the cryoTune is the solution!
In our laboratory for contract measurements (LabSPA), extensive investigations on the physisorption of various sample gases (see table below) using nitrogen cooling are currently being carried out. The cryoTune, an option for almost all commercially available physisorption devices, is used for this purpose. The cryoTune provides the experimental basis for sorption investigations and offers the following advantages:
- Economical – The cryoTune provides a cost-effective substitution of expensive, other liquid gases by the economical and efficient consumption of low-cost liquid nitrogen for cooling.
- Precise – In contrast to boiling point temperature control, the temperature control of the measuring cell is independent of air pressure. In addition, the cold zone of the measuring cell is reduced to a minimum and remains constant over the entire measuring period.
- Flexible – The cryoTune can be used with all common sorption instruments and opens a wide temperature measuring range that is otherwise difficult to access.
Inside the cryoTune, the measuring cell for temperature control is not directly immersed in liquid nitrogen, but is located in a heat conducting block that can be heated close to the sample and allows heat transfer between measuring cell and liquid nitrogen. Through controlled heating, a temperature range above the boiling point of nitrogen as the measuring temperature can be precisely set and thus different temperatures can be maintained. When using the innovative cryoTune technology, it is possible to use a wide range of adsorptives for texture characterization: the following table shows the different gases, their boiling temperature, liquid density, the space requirement of the adsorptive, the saturation vapor pressure and the non-ideality factor of the adsorptive.
|Adsorptive||Boiling point T [K]||ρLiquid [g/cc]||am for BET surface [nm2] from ρLiquid *4||p0 [kPa]||Non-ideality factor Fni of the adsorptives *3 [10-5]|
*2…p0 and ρLiquid of the undercooled liquid
*3…mean value from van der Waals- und Bethelot equations
*4…calculated according to: