Exploring the practical conditions for synthesis of [B, Ti]-ZSM-۵ zeolite using tetrapropylammonium bromide

Since the first synthesis of Ti containing zeolite (titanosilicate) with ZSM-۵ structure in ۱۹۸۳, there have been many investigations into synthesis, characterization, and catalytic applications of titanosilicates [۱]. Titanosilicates have usually been synthesized in alkali-free conditions due to the formation of extra-framework species in the presence of alkali ions. This requiers the use of large quantities of costly tetrapropylammonium hydroxide (TPAOH) template for the synthesis of ZSM-۵ type titanosilicates, which can simultaneously adjst the pH of reaction to the desired values [۲]. To avoid using TPAOH, some authors suggested crystallization of titanosilicates from gels containing mixtures of ammonia or amines and tetrapropylammonium bromide (TPABr) [۳, ۴]. In this regards, we investigated the synthesis of borotitanosilicate ([B, Ti]-ZSM-۵) zeolite using TPABr under optimised conditions. The XRD patterns and FT-IR spectra revealed the succesful synthesis of crystalline ZSM-۵ zeolite without any TiO۲ impurities in which Ti ions are incorporated in tetrahedral positions. The coffin-shaped morphology was observed for zeolite particles in SEM images.

کلیدواژه ها:

ZSM-۵ ، Borotitanosilicate ، Tetrapropylammonium bromide ، Coffin-shaped