PHYSICAL GAS ADSORPTION

In physical gas adsorption an inert gas as nitrogen (or argon, krypton, carbon dioxide) is adsorbed on a solid material. Prior to the measurement the sample is pretreated at elevated temperature in vacuum or flowing gas to remove any contaminants.
Two different techniques can be distinguished:
The flow technique uses a TCD detector to obtain information on the amount of physisorbed gas only resulting in a BET surface area and/or total pore volume. The volumetric technique provides more information, since many adsorption and/or desorption points are measured to give a full isotherm.

The flow measurements are performed on a Qsurf M3 analyzer and the report consists of a single value for the BET surface area and/or total pore volume. The volumetric adsorption measurements are performed on a Quantachrome Autosorb-6B (N2), Quantachrome NOVA 1200 (CO2) or Micromeritics ASAP 2010 (Ar) and the report can be a single value for surface area up to a full report on isotherm, surface area, total pore volume and pore size distribution