Disordered Molecular Sieve with Branched Mesoporous Channel Network

Abstract

A disordered mesoporous silica material has been prepared using polymerization of silicate anions surrounding surfactant micelles in the presence of organic salts. The local structure of the material has been investigated using a transmission electron micrograph image of platinum wire grown inside the mesopores. This micrograph imaging technique, developed in the present work, clarifies that the pore structure is a three-dimensional, disordered network of short wormlike channels while the channel widths are uniform. The fully disordered channel branching similar to a three-dimensional fractal with truly uniform channel widths distinguishes the present material with respect to the recently found ordered mesoporous molecular sieve MCM-41. The branching channel structure has a remarkable advantage for adsorption and catalytic applications, compared with the MCM-41. The structure also exhibits outstanding hydrothermal stability. The recognition of the disordered, branching structure with uniform channel widths is expected to open a new class of noncrystalline molecular sieves, and the unique structures with good stability will provide new opportunities for rational design of heterogeneous catalysts, adsorbents, and other related materials.