A non-sodium synthesis of highly ordered V-MCM-41 and its catalytic application in isomerization

A rapid non-sodium process was developed to synthesize highly ordered V-MCM-41 mesoporous materials with atomic level dispersed vanadium species. NH₃•H₂O instead of NaOH was used to maintain the moderately basic synthesis condition. The characterization results of N ₂ physisorption and XRD showed that the synthesized samples had highly ordered hexagonal structure. UV-Vis, UV-Raman, and EPR spectra provided evidence that most vanadium ions were tetrahedrally incorporated into the framework of siliceous MCM-41. The NH₃-TPD proved the mild acidity of V-MCM-41 due to the incorporation of vanadium cations. The most important variables were structural order and vanadium loading which can be controlled easily by changing synthesis variables in such a way that collapse of the V-MCM-41structure did not occur. The synthesized V-MCM-41 catalysts successfully catalyzed the isomerization of heptene. High conversion and isomer selectivity were achieved with good catalytic stability. The structure of V-MCM-41 can be well preserved after reaction.