Effect of Silanol Content in Gel and Mother Liquor on MFI-type Silicalite Synthesis from Crystalline Quartz Dissolved in High-concentration Sodium Hydroxide

Abstract

To improve the effective utilization of currently unused resources, we investigated the synthesis of MFI-type silicalite from crystalline quartz and quartz glass scraps, which are rarely used in the synthesis of zeolites and related compounds. MFI-type silicalite can be synthesized by first heating and dissolving crystalline quartz in a highly concentrated aqueous solution of sodium hydroxide. This study used analysis of variance and multiple regression analysis to investigate the effect of the silanol content in the gel and mother liquor on the synthesis of MFI-type silicalite from quartz. We found that the crystallinity of MFI-type silicalite decreased with higher surface silanol content in the gel and with higher proportion of dissolved monomeric silicate ions (corresponding to the silanol content) in the mother liquor. Furthermore, we found that the interaction between the gel and mother liquor positively affected the crystallinity of MFI-type silicalite.