Gas adsorption (BET)

Information obtained

  • Surface area of a powder
  • Porosity, pore size distribution, average pore size
  • With certain set ups, one can determine the change in enthalpy of adsorption (ΔHads) for volatile compounds, such as water, ethanol etc.

Principle

BET is named for Brunauer, Emmett and Teller, the three physicists who developed this technique. It relies on the analysis of the amount of nitrogen, krypton or any other gas that adsorbs onto the surface of a dry solid as function of pressure.

BET_better_2_1_505px_copie
Typical BET plot obtained for gas adsorption, to determine the surface area of the powder sample. In this case, surface area is about 1 m2 per gram of the powder.