mikroporøse

Mikroporöse materials are solids that contain a network of pores predominantly smaller than 2 nanometers in diameter. The resulting high internal surface area enables selective adsorption and separation of small molecules. By IUPAC convention, pores below 2 nm are micropores; pores between 2 and 50 nm are mesopores; larger pores are macropores.

Common examples include zeolites, activated carbons, microporous silica, metal-organic frameworks (MOFs) with microporous channels, covalent organic frameworks, and certain porous polymers. Each class offers different chemical environments and stability.

Characterization commonly uses gas adsorption isotherms, especially nitrogen at 77 K, to determine surface area by the BET method and pore size distribution by methods such as t-plot or Horvath-Kawazoe for micropores. Ultrafine pores may be probed with CO2 adsorbed at 273 K to reveal sub-nanometer pores.

Applications include catalytic supports, gas separations (such as CO2 capture and hydrocarbon separations), hydrogen storage, environmental remediation, and sensors. The small pore size provides selectivity but can limit diffusion of larger molecules.

Microporous materials are synthesized by hydrothermal or solvothermal routes, templating, or chemical vapor deposition, depending on the material class. Challenges include thermal and chemical stability, pore blocking by impurities, and diffusion limitations for larger molecules.