Titanosilicate porous thin film on silicon substrate as catalyst for hydroxylation of phenol in continuous flow reactor

Abstract

This research investigated the preparation of titanium silicalite-1 and metal titanium silicalite-1 materials. The synthesized materials were applied into 2 parts as powder and thin film forms. Both titanium silicalite-1 form and metal titanium silicalite-1 thin film were synthesized by seeding together with hydrothermal method, while metal titanium silicalite-1 powder was prepared by hydrothermal method. The silicon wafer is used as substrate for synthesizing thin film material. The interested metals in this research were vanadium and iron. All synthesized materials were characterized by X-ray powder diffraction, DR-UV spectrophotometry, N2 adsorption-desorption, scanning electron microscopy and inductively coupled plasma mass spectrometry. All prepared materials showed characteristic of MFI structure. The smaller particle size was resulted from the higher seed loading as 10 wt.% base on silica source. After metal addition, the crystallinity of synthesized materials was decreased. The catalytic activities of synthesized materials were investigated in phenol hydroxylation with hydrogen peroxide. All powder synthesized materials were carried out in batch reactor. The influence of reaction parameter, including mole ratio of phenol/ hydrogen peroxide and reaction temperature were examined. Among several of particle size of titanium silicalite-1 catalysts, the titanium silicalite-1 seed illustrated the highest phenol conversion at 30.36% due to the smallest of particle size. The iron titanium silicalite-1 demonstrated high phenol conversion and highest catechol selectivity as 43.46 and 64.5%, respectively. In the continuous flow reactor at 4 µl/min displayed the highest phenol conversion when titanium silicalite-1 thin film was used. The phenol conversion of iron titanium silicalite-1 thin film was lower than titanium silicalite-1 thin film due to the thinner film thickness. However, iron titanium silicalite-1 provided the high selectivity to catechol same as in batch reaction.