MCA Services - Porosimetry and Pore Size Distribution

MCA SERVICES

PORE SIZE DISTRIBUTION

Home

     Pore size distribution by
     Nitrogen Adsorption
     Isotherm

Pore size distribution by
Mercury Porosimetry

Pore sizes are often quoted in terms of their range - micropore, mesopore and macropore, the table below provides a guide for the categorisation of pore diameters within these designations.

Pore size classifications ^[1]

Classification	*Pore diameter range (nm)**	*Pore diameter range (μm)**	*Pore diameter range (Å)**
Micropores	< 2.0	< 0.002	< 20
Mesopores	2 – 50	0.002 – 0.05	20 – 500
Macropores	> 50	> 0.05	> 500

^[1] Pure and Applied Chemistry, 57, No 4, (1985), 603-619.

*These ranges refer to the diameter of a cylindrical pore or the width of a slit-shaped pore.

There is no single porosimetry technique for the determination of the pore size distribution of a sample throughout the entire pore size range. The most common techniques for porosimetry analysis are mercury porosimetry (for the meso and macro pore range) and gas adsorption (for the micro and meso pore range).

MCA Services offers these two porosimetry techniques for the determination of the pore size, pore area and pore volume distribution of sample materials. The choice of technique is dependent on the expected pore sizes within the sample.
For microporous and mesoporous materials the gas adsorption technique, using nitrogen gas, is applied using our Micromeritics TriStar apparatus. The pore size range covered by this technique is typically 0.55 nm to 360 nm and this forms our SC3 test from which pore size, pore area and pore volume data is reported.

porosity testing by nitrogn gas porosimetry showing pore size distribution

Porosimetry using nitrogen gas adsorption

For materials having larger pores mercury porosimetry is recommended and covers the approximate range 0.007 μm to about 600 μm (mesoporous to macroporous materials), depending on the nature of the material. This is conducted using a Micromeritics AutoPore mercury porosimeter and forms our SC11 test from which pore size, pore area and pore volume data is reported. Furthermore, this test can be combined with the measurement of bulk density and sample porosity.

An alternative method for the determination of the total pore volume of a sample is by the combination of mercury pycnometry and helium pycnometry. A description of this technique is provided on our density analysis pages under our SC8 analysis for porosity testing.

Naturally, each test can be conducted independently of the other, or both can be applied to a sample in order to gain data on a more complete range of pore sizes.

porosity testing by mercury porosimetry showing pore size distribution

Porosimetry by mercury intrusion porosimetry

For further information on each technique and the data provided as part of our standard report packages please follow the links below. Alternatively the staff at MCA Services may be contacted to discuss and advise on suitable techniques for the analysis of client samples.

Micropores