Merging Pore Size Distributions from CO2 and N2 Adsorption Measurements

Hierarchical carbons are used in industries ranging from energy and gas storage to separations and catalysis. For these materials, knowing the full micro- and mesopore size distribution is crucial to understanding application success. The Anton Paar Nova series can measure the micropore size distribution of these materials using CO2 adsorption at 273 K, and the mesopore size distribution using N2 adsorption at 77 K, without the need for higher end vacuum and measuring components. These results are processed in the Kaomi for Nova software, where the user can cleanly merge these two distributions into one micro / mesopore size distribution.


More and more researchers are interested in synthesizing and characterizing carbon materials that contain a “hierarchical” pore network of connected micropores (< 2 nm) and mesopores (2-50 nm). These hierarchical carbon materials are advantageous for transport applications in batteries and electrochemical energy storage, in catalysis, biomedical applications, and gas storage and separation, among others. 


One efficient way to characterize the pores in these different size ranges includes the use of CO2 adsorption for micropore analysis and N2 adsorption for mesopore analysis. Traditional low pressure N2 micropore analysis is very time consuming, whereas CO2 (273 K) micropore measurements are much faster due to the higher experimental temperature and smaller kinetic diameter of CO2.  In addition, CO2 measurements do not require low pressure transducers or turbomolecular vacuum pumps, which means that they can be easily run on an instrument with the capabilities of the Anton Paar Nova series.

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