Metathesis of 2-butene to propylene over W-mesoporous molecular sieves: A comparative study between tungsten containing MCM-41 and SBA-15

摘要

Mesoporous silica (MCM-41 and SBA-15) having tungsten oxide in the framework was synthesized by hydrothermal crystallization process using CTAB and P123 as structure directing agents, respectively Tungsten oxide was supported on the MCM-41 and SBA-15 by wet impregnation method for a compar- ative study. The synthesized materials were characterized by XRD, N2 adsorption-desorption, NH3-TPD, pyridine-FT-IR, UV-vis DRS and Raman spectroscopy techniques. The catalysts were used to perform metathesis reaction of 2-butene in a fixed-bed reactor at different temperatures and under atmospheric pressure. It was observed that catalysts having tungsten oxide in the framework of mesoporous silica exhibited higher activity as compared to tungsten oxide impregnated catalysts. The results revealed that WO3-MCM-41(30) catalyst has much higher activity at a low temperature (450 °C) as compared to WO3-SBA-15(30).At550°C.WO3-MCM-41(30) and WO3-SBA-15(30)showed comparable activity with highest propylene yield of 39 mol% and 37 mol%, respectively. The higher metathesis activity of WO3-MCM-41 catalysts can be related to the well-dispersed active tetrahedral tungsten oxide species as evidenced from XRD, UV-vis DRS and Raman spectroscopy results.