Pore wall of a mesoporous molecular sieve derived from kanemite

The pore diameters and pore wall thicknesses of the mesoporous molecular sieves FSM-16 derived from a layered silicate (kanemite) were estimated by X-ray diffraction, physisorption, transmission electron micrographs, Si-29 MAS NMR, and modeling and simulation. The XRD simulation with a simple model of a hexagonal array of cylinders gave reasonable values coinciding with those obtained by TEM and nitrogen adsorption, with some corrections. As-synthesized FSM-16 material had pore walls 0.4 nm thick, corresponding to the slightly less wrinkled single SiO4 tetrahedral layer observed in the crystalline layered silicate minerals, and an apparent pore diameter of 4.2 nm. Surfactant-free FSM-16, formed by calcination and exchange for H+, had thicker pore walls of 0.8 and 0.9 nm corresponding to double SiO4 tetrahedral layers and pore diameters of 3.4 and 3.7 nm.