Synthesis and characterization of mesoporous V-MCM-41 molecular sieves with good hydrothermal and thermal stability

Abstract

Stable V-MCM-41 mesoporous materials have been synthesized by hydrothermal method, using hexadecyl-trimethyl-ammonium bromide as template, and industrial Na 2O·(3.3–3.5)SiO 2 as the source of much cheaper silica instead of conventional expensive organic precursors. Several modern techniques like XRD, N 2 adsorption, FT-IR, UV–vis and SEM have been utilized to characterize the framework structure and texture of the samples. The results of N 2 adsorption and X-ray diffraction showed that the synthesized samples had a high ordered hexagonal structure, good hydrothermal stability and thermal stability. The selective oxidation of styrene using hydrogen peroxide as oxidant over V-MCM-41 samples showed a good catalytic performance of partial oxidation, the phenylacetic acid was the principal product (the selectivity value was 49.4%). Even after a thermal treatment at 900 °C in air for 12 h or a hydrothermal treatment in boiling water for 8 days, each of the two resultant materials could retain the ordered channels and a high BET surface area. UV–vis spectra provided strong evidences that most of vanadium ions were incorporated into the framework of siliceous MCM-41 sample.