Surface analysis
BET Surface Area and Porosity Analysis
BET gas adsorption analysis evaluates specific surface area and can support pore-volume and pore-size characterization of porous solids.
BET analysis uses a gas adsorption isotherm, commonly nitrogen at cryogenic temperature, to calculate specific surface area over an appropriate relative-pressure region. RNDgrid coordinates degassing conditions, sample mass, adsorptive, and requested pore analysis with partner laboratories. Degassing must remove adsorbed moisture or volatiles without changing the material.
When this method is useful
- Catalysts, activated carbon, adsorbents, battery materials, powders, ceramics, pigments, and porous solids
- Comparing synthesis, activation, heat treatment, ageing, or surface modification
- Surface-area, pore-volume, and mesopore distribution studies where the selected model is appropriate
What the report can include
- Adsorption/desorption isotherm and BET specific surface area
- Total pore volume at a stated relative pressure when requested
- Optional BJH or other model-based pore-size distribution within suitable ranges
Sample preparation and scoping
- Provide enough dry, representative material and disclose thermal stability and volatile components.
- Agree degassing temperature and duration using prior thermal knowledge where possible.
- Very low-area samples may require more mass or a different gas/instrument configuration.
Limitations to consider
- BET assumptions and chosen fitting range affect the calculated result.
- Nitrogen at 77 K may not characterize every microporous material adequately; carbon dioxide or argon may be preferable.
- Pore-size models have defined applicability ranges and should not be interpreted beyond them.
Capabilities, detection limits, accreditation scope, and turnaround vary by method and partner laboratory. Confirm the final scope in the quotation before sending samples.
Questions to answer before booking
- Is the priority total surface area, microporosity, mesoporosity, or comparative quality control?
- What degassing temperature can the sample tolerate without changing?
- Would nitrogen, carbon dioxide, or another adsorptive best match the pore range?
Related methods
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