Synthesis of ETS-10-like vanadosilicates using 2,6-dimethylpiperidinium cation derivatives as organic templates

Systematic vanadosilicate syntheses were performed using derivatives of 2,6-dimethylpiperidine as organic structure-directing agents (SDAs). Physicochemical analyses of the vanadosilicate materials obtained were carried out by X-ray diffraction (XRD), Raman spectroscopy, infrared (IR) spectroscopy, UV-visible (UV-Vis) spectroscopy, and solid-state NMR spectroscopy (Si-29 and V-51 MAS NMR). The experimental results indicated that the presence of the organic templates had different effects on the final phases of the synthesized vanadosilicates. The XRD results showed that 1,1,2,6-tetramethylpiperidinium (SDA 1) favored synthesis of the known AM-6 vanadosilicates, isostructural to the ETS-10 titanosilicate, while the other organic templates 1,1-diethyl-2,6-dimethylpiperidinium (SDA 2), 6,10-dimethyl-5-azoniaspiro[4.5]clecane (SDA 3), and 1,5-dimethyl-6-azoniaspiro[5.5]undecane (SDA 4) directed the formation of vanadosilicates with different phases, such as EVS-10. Strong Raman bands at 870 and 1035 cm(-1) indicated vibrational modes associated with the highly symmetric vanadia octahedra. Chemical shifts at -96 ppm (Si-29 MAS NMR), - 610, and - 570 ppm (V-51 MAS NMR) provided further evidence of the incorporation of vanadium into the structures of the vanadosilicates prepared using these novel derivatives of 2,6-dimethylpiperidinium cations as SDAs.