Propertiesmicroporosity

Propertiesmicroporosity refers to the characteristics and behaviors of microporosity in porous materials. Microporosity consists of pores with diameters below 2 nanometers. Materials with microporosity typically have very high internal surface areas and strong adsorption affinities for small molecules, which influence storage, separation, and catalytic performance. In practice, microporosity often coexists with larger pores, creating hierarchical structures that affect diffusion and accessibility.

Characterization of microporosity relies on adsorption measurements. Nitrogen adsorption at 77 Kelvin is commonly used to estimate surface area (via the BET method) and to probe pore structure. Micropore volume and size distribution are often obtained with methods such as the t-plot, the Dubinin-Radushkevich equation, or NLDFT-based analyses, which help distinguish micropores from mesopores and macropores.

Materials emphasizing microporosity include zeolites, activated carbons, metal-organic frameworks, and covalent organic frameworks. The degree of microporosity is tuned during synthesis, aging, activation, or templating, and it can be modified post-synthesis by chemical treatments. Microporosity governs selectivity for small molecules, diffusion rates, and overall adsorption capacity.

Applications span gas storage and separation, catalysis, and environmental remediation. While high microporosity enhances adsorption, it can also limit access for larger molecules and slow diffusion, so many materials employ hierarchical porosity to balance capacity and transport.