Preparation of Porous Consolidated Zeolite from Silica Fume and Characteristics of Humidity Conditioning

Abstract

Silica fume (SF) is a byproduct when purifying silicon materials used for semiconductors and so on. The development of effective utilization of SF has been paid attention to, accompanied by increase in production of SF due to increase in the demand for semiconductor. Zeolite is one of functional materials with ability toward to catalysts, ion exchange and reversible dehydration, because of a crystalline structure which has same size micropores of molecular and exchangeable cations. In general, zeolite is produced as the fine powders of several microns by a hydrothermal synthesis method. It is difficult to handle the fine powder of zeolite, therefore a binder is added to mold it. However, the addition of a binder causes the decrease of zeolite content and degradation of performance for micropores in zeolite, resulting in reduction of the function of zeolite. Our research group has reported that zeolite could be synthesized as a consolidated body by using a geopolymer reaction. In this study, the possibility of the usage of SF as a raw material for a functional material, especially consolidated zeolite, was investigated to suggest high-value application of SF. It was revealed that consolidated zeolite can be synthesized with SF as a raw material. It was also proved that foamed zeolite was obtained by adding Si powder and zinc stearate. The foamed zeolite exhibited better humidity conditioning characteristics than the unfoamed zeolite. Thus, the possibility of effective utilization of SF was suggested for a functional material.