Mercury Intrusion Porosimetry Combined With Pore Size Distributions Calculated from Gas Adsorption Isotherms

MicroActive 2.0 and MicroActive for 3Flex include a powerful utility for including the pore size distribution from mercury porosimetry analyses with pore size distributions calculated from gas adsorption isotherms. This new import function enables users to rapidly view micro, meso, and macro pore size distributions in one easy to use application.

A new import function has been added that enables users to rapidly include pore size distributions from other devices to be included into the standard Micromeritics sample file. From a simple text file, the pore size data from the external source such as a mercury porosimeter is imported. The first line of a text file includes a description, size units, quantity units, and type of data with the following format.

The porosimetry data then follows with the pore width in the first column and the quantity in the second column. An example of the format is given in Figure 1. The intrusion data must be strictly increasing and extrusion data must be strictly decreasing.

Example file format for importing mercury porosimetry data.

Figure 1. Example file format for importing mercury porosimetry data.

The cumulative or incremental data is available from the Micromeritics AutoPore 9500 application. The data may be copied by right-clicking on either the cumulative or incremental pore volume graphs generated by the AutoPore reports and then using the Copy as text option.

A file that needs to be imported is restricted to extrusion or intrusion data. However, multiple files may be imported to allow the inclusion of both intrusion and extrusion data.

Importing Pore Volume Data

Using the Import function located on the report options tab in the advanced tab of the SMP file, the pore volume data may be integrated into a sample file (SMP file)as seen in Figure 2.

The import utility is found on the Advanced tab of the SMP file.

Figure 2. The import utility is found on the Advanced tab of the SMP file.

Figure 3 shows the import file selector listing each pore size by description

The import file selector lists each pore size distribution by description.

Figure 3. The import file selector lists each pore size distribution by description.

In case there is an error while importing the mercury porosimetry data, a descriptive message is displayed that includes a description of the correct file format as shown in Figure 4.

Error message for improperly formatted pore volume data file.

Figure 4. Error message for improperly formatted pore volume data file.

The imported data may then be used as an overlay with cumulative, differential, or log differential pore size distributions. The overlay is selected by editing the options for the BJH, Dollimore-Heal, Horvath-Kawazoe, and DFT pore size reports. Each report has the option for including an overlay and the imported data may be selected as seen in Figure 5.

Imported data may be used as an overlay in cumulative, differential, and log-differential pore size distributions.

Figure 5. Imported data may be used as an overlay in cumulative, differential, and log-differential pore size distributions.

Example

Commercial catalysts are analyzed commonly using nitrogen adsorption to measure the porosity and surface area. The pore size distribution may then be calculated from the nitrogen adsorption isotherm using BJH.

Normally mercury porosimetry is employed to determine the pore volume distribution of catalysts and the pore volume distribution may be overlaid with the distribution calculated from the nitrogen adsorption isotherm.

The Micrometrics chemisorptions reference material is 0.5 wt% platinum on alumina. The sample was characterized using nitrogen adsorption and mercury porosimetry. The nitrogen desorption and adsorption isotherms were used to determine the pore size distribution using the BJH method. Both mercury intrusion and extrusion data were imported into the gas adsorption SMP file as shown in Figure 6.

Overlay of BJH desorption, mercury intrusion, and mercury extrusion log differential pore size distributions for alumina pellets

Figure 6. Overlay of BJH desorption, mercury intrusion, and mercury extrusion log differential pore size distributions for alumina pellets

Summary

The MicroActive version 2.0 offers novel and unique capabilities for integrating pore volume data from mercury intrusion analyses with the pore size distributions calculated from gas adsorption isotherms.

The MicroActive software is compatible with SMP files from Micromeritics broad range of gas adsorption instruments and offers a new capability for examining new or historical pore volume distributions.

This information has been sourced, reviewed and adapted from materials provided by Micromeritics Instrument Corporation.

For more information on this source, please visit Micromeritics Instrument Corporation.

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