High pH promoting the synthesis of V Silicalite 1 with high vanadium content in the framework and its catalytic performance in selective oxidation of styrene.
It is difficult to synthesize a Silicalite 1 molecular sieve with a high vanadium content in the framework, because heteroatoms significantly affect the formation of V Silicalite 1. Here, V Silicalite 1 with a high vanadium content in the framework of the molecular sieve was successfully synthesized by controlling the pH at high levels. In the process of hydrothermal synthesis, OH ions effectively promoted the entry of vanadium atoms into the framework of the molecular sieve. Samples of V Silicalite 1 with different vanadium contents were characterized by XRD, FTIR, UV vis, XPS, EPR, ICP, FE SEM, elemental mapping, N2 adsorption desorption, and TPR, which confirmed that vanadium atoms successfully replaced silicon atoms in the framework. V Silicalite 1 exhibited good catalytic performance in the selective oxidation of styrene at different temperatures, with a styrene conversion of up to 84.89% and a selectivity of 91.04% for styrene oxide at 25 degC and a styrene conversion of 97.47% and a selectivity of 80.97% for benzaldehyde at 85 degC. This study provided a new idea for the synthesis of molecular sieves with high vanadium contents in the framework. Besides, it also enabled the direct application of vanadium doped molecular sieves for the catalytic oxidation of styrene in industry.
Dalton transactions