Postsynthesis of Ti-UZM-35 titanosilicate as efficient catalyst for phenol hydroxylation reaction

Abstract

Abstract The MSE-type aluminosilicate UZM-35 was efficiently prepared via adding a rational amount of MCM-68 as seed and using commercially available dimethyldipropylammonium hydroxide (DMDPAOH) as the structure-directing agent. The operation window of Si/Al ratio was widened significantly and the synthetic system was less sensitive to the Na+/K+ ratio, compared to the synthetic systems of MCM-68 and traditional UZM-35 without seed. The crystallization time was also shortened to 4 days, compared to MCM-68 (14 days) and traditional UZM-35 (7 days). Moreover, the framework of UZM-35 kept intact after the dealumination process including high temperature calcination and acid treatment. Tetrahedrally coordinated Ti4+ ions were introduced into the framework of highly dealuminated UZM-35 via solid-gas reaction with TiCl4 vapor and the obtained Ti-UZM-35 exhibited comparable catalytic activity to Ti-MCM-68 in the phenol hydroxylation reaction. The H2O2 feeding style was adjusted in present work to improve the H2O2 utilization efficiency up to 70%. In addition, the Ti-UZM-35 catalyst was stable in the regeneration-reuse cycles.