Elucidation of Detailed Pore Structure of (NH4)4SiW12O40 Sponge Crystal

Abstract

Pore structure of (NH4)4SiW12O40 sponge crystal was successfully elucidated by means of Ar adsorption isotherm analysis combined with molecular probe method and molecular modeling. The pores consist of spherical voids or “cages” with diameter of ca. 12 Å and these are connected by smaller “windows”. These “cages” and “windows” are clearly resolved in the pore size distribution analysis for the first time. Molecular probe method elucidated the diameter of the “windows” is larger than 8.5 Å and smaller than 10.2 Å, being consistent with molecular modeling.