Ultrasonic Synthesis of Silica−Alumina Nanomaterials with Controlled Mesopore Distribution without Using Surfactants

Abstract

A novel sol-gel process has been developed for the synthesis of amorphous silica-aluminas with controlled mesopore distribution without the use of organic templating agents, e.g., surfactant molecules. Ultrasonic treatment during the synthesis enables production of precursor sols with narrow particle size distribution. Atomic force microscopy analysis shows that these sol particles are spherical in shape with a narrow size distribution (i.e., 13-25 nm) and their aggregation during the gelation creates clusters containing similar sized interparticle mesopores. A nitrogen physiadsorption study indicates that the mesoporous materials containing different Si/Al ratios prepared by the new synthesis method has a large specific surface area (i.e., 587-692 m 2 /g) and similar pore sizes of 2-11 nm. Solid-state 27 Al magic angle spinning (MAS) NMR shows that most of the aluminum is located in the tetrahedral position. A transmission electron microscopy (TEM) image shows that the mesoporous silica-alumina consists of 12-25 nm spheres. Additionally, high-resolution TEM and electron diffraction indicate that some nanoparticles are characteristic of a crystal, although X-ray diffraction and 29 Si MAS NMR analysis show an amorphous material.

Synthesis of MCM-41 from coal fly ash by a green approach: Influence of synthesis pH

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Effect of ultrasonic treatment on dispersibility of Fe3O4 nanoparticles and synthesis of multi-core Fe3O4/SiO2 core/shell nanoparticles

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A novel and template-free method for the spontaneous formation of aluminosilicate macro-channels with mesoporous walls

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