Characteristics of helium adsorption on microporous solids under cryogenic conditions.

A new volumetric method using helium adsorption was proposed to make microporous solids with clear pore structures. Adsorption equilibria of helium on silica-alumina, activated carbon and zeolites were measured at a temperature around its boiling point. The helium adsorption isotherms obtained were compared with the nitrogen adsorption isotherms. As a result, the amounts of helium adsorbed on all adsorbents used were much greater than those of nitrogen adsorbed in the low relative pressure region, indicating that helium is a useful molecule to investigate microporous structures of such materials. Therefore, the possibility that this method be applied to micropore characterization was suggested. The results of B.E.T. specific surface areas also support this conclusion.