The evidence of NMR diffusometry on pore space heterogeneity in activated carbon

With the advent of nanoporous materials with hierarchical pore structure, pore space exploration becomes an increasingly complex task which depends on the successful inclusion of novel techniques of sample characterization, in addition to the established ones. We present the results of an in-depth pulsed field gradient (PFG) NMR study of guest diffusion in an activated carbon with a two-modal pore structure (MA2). The pronounced distribution of the local diffusivities is taken as an indication of notable sample heterogeneities. The options of their further characterization by intentionally varying the parameters and conditions of the diffusion measurements are discussed.

Pulsed field gradient NMR diffusion study reveals heterogeneous structure of activated carbon.Figure optionsDownload as PowerPoint slideResearch highlights
► Diffusive mass transport in an activated carbon material with a hierarchical pore structure is studied using pulsed field gradient NMR.
► The distribution of the local diffusivities obtained is assigned to result from a sample heterogeneity.
► The correlation length of the heterogeneities is estimated to exceed 10 μm.