BET

The method of Brunauer, Emmet, and Teller is employed to determine surface area on a model of adsorption which incorporates multilayer coverage.

Application

1. PURPOSE

The Micromeritics Tri Star 3000 Surface Area and Porosity Analyzer is used for N2 adsorption measurements.

2. SCOPE

Calculation of specific surface area from adsorption and desorption isotherm branch according to BET or single point method
Calculation of pore volume and pore size distribution from adsorption and desorption isotherm branch according to BJH method.

3. TARGET GROUP

Solid state materials, micro-, mesoporous materials

4. DEFINITIONS AND ABBREVIATIONS

Adsorption - adhesion (binding) of a species (adsorptive) to an interface (adsorbent) Desorption – reverse to adsorption process Specific surface area - the accessible internal and external surface to an adsorptive for 1 gram of solid.

Total pore volume – the volume of the accessible pores to an adsorptive for 1 gram of solid Adsorption isotherm – plot of the amount of gas adsorbed vs. pressure (p/po) BET – model developed by Brunauer, Emmett and Teller describing molecular adsorption, can be used to measure (BET) surface area of materials.

BJH - model developed by Barrett, Joyner & Halenda describing molecular adsorption, can be used to calculate pore size distribution of materials.

Single point approach – method for calculation surface area based on the point on isotherm which correspond to the formation of the statistic monolayer on the surface.