Influences of synthesis conditions on preparation and characterization of Ti-MWW zeolite membrane by secondary hydrothermal synthesis

Abstract

Influences of synthesis conditions on the growth and catalytic performance of the Ti-MWW zeolite membrane are investigated in this work. Medium crystallization time, crystallization temperature, molar ratios of the precursor synthesis gels (TiO 2 /SiO 2 , H 2 O/SiO 2 and B 2 O 3 /SiO 2 ) are crucial to prepare the compact and good catalytic performance Ti-MWW zeolite membranes. High crystallization temperature and long crystallization time cause a hetero zeolite phase membrane on the mullite support. Excessive titanium in the precursor synthesis gel could easily arise TiO 2 particles and non-framework TiO 6 species on the membrane surface, which are greatly decreased the catalytic performance of the Ti-MWW zeolite membrane. Dilute precursor synthesis gel is not favor for preparing dense Ti-MWW zeolite layer. The as-synthesized Ti-MWW zeolite membrane is applied as catalytic membrane reactor for phenol hydroxylation by pervaporation in this study, the phenol conversion and benzenediol selectivity are 41.42% and 98.33%. • Excessive titanium of precursor synthesis gel cause TiO 2 particles and non-framework TiO 6 species. • High crystallization temperature and long crystallization time could lead to form a hetero phase Ti-MWW zeolite membrane. • Dilute precursor synthesis gel was not favor for preparing dense Ti-MWW zeolite layer. • Phenol conversion and benzenediol selectivity of Ti-MWW zeolite membrane are 41.42% and 98.33%.