Brunauer Emmet Teller (BET) analyzer

Instrument details:
Type: Gas Sorption System
Make: Quantachrome Instruments
Model No: Autosorb-IQ-C-MP (Model: 7 ASiQWin Version: 5.2x)
Essential specification:
Measurement range: Pore Size range(0.35 to 500 nm (3.5 to 5000 Å)
Temperature Range: 20 – 320 K
Temperature ranges:: Room temperature to 300 degree Celsius
Ultimate vacuum, analysis (MP/XR): 5x10-10 mbar
P/Po range (XR):: <1 x 10-8 – 0.999
Chemisorption furnace, max temperature : 1100°C
Software:: ASiQwin
Sample Type:: Solid in powdered form (dry)
Minimum sample volume: 25mg to 2 g
Accuracy: 0.1/1 torr transducer accuracy (MP/XR)<0.15% of reading(0.05%)
Precision / Repeatability:
Result: Specific surface area in m²/g or m²/cm³
Working principle:
The autosorb iQ operates on the BET theory (abbreviated from Brunner-Emmett-Teller theory) is used to measure the surface area of solid or porous materials. It gives important information on their physical structure as the area of a material’s surface affects how that solid will interact with its environment. Many properties such as dissolution rates, catalytic activity, moisture retention, and shelf life are often correlated to a material’s surface area. Using the BET theory, the true or specific surface area, including surface irregularities and pore walls, of a particle is determined at an atomic level by adsorption of an unreactive gas. Because most gases and solids interact weakly, the solid material must be cooled, typically using a cryogenic liquid. The temperature of the solid sample is kept constant, or under isothermal conditions, while the pressure or concentration of the adsorbing gas is increased. As the relative pressure is increased, more and more molecules adsorb on the surface. A thin layer will eventually cover the entire in a single or mono-layer. The number of gas molecules in the monolayer is recorded from the volume adsorbed. Since the cross-sectional area of the adsorbate is known, the area of the accessible surface may be calculated.