Aluminophosphate-based tubular mesoporous materials containing framework silicon, vanadium and manganese have been successfully synthesized. X-ray diffraction and transmission electron microscopy reveal that these solid products possess disordered arrays of tubular mesoporous channels which mimic the hexagonal MCM-41 structure. N2 adsorption further suggests that these materials are relatively thermally stable, have an average free mesopore diameter of 35 Å and have high BET specific surface areas up to 700 m2/g. Electron probe microanalysis reveals that the overall P/Al ratio of these materials is less than unity and 27Al and 31P MAS NMR shows that both tetrahedral and octahedral aluminum occur as well as tetrahedral phosphorous and hydroxylated phosphorus species, indicating a nonideal aluminophosphate framework. Incorporation of silicon results in a less disordered mesoporous structure and substantial increases in the relative amounts of tetrahedral aluminum and tetrahedral phosphorus. Transition metal ions can be incorporated up to V/Al = 0.10 for vanadium and Mn/Al = 0.20 for manganese. Electron spin resonance and diffuse reflectance ultraviolet-visible spectroscopies reveal that both vanadium and manganese are present as isolated species and suggest framework locations for these ions.
|Number of pages||8|
|Journal||Studies in Surface Science and Catalysis|
|Publication status||Published - 1 Jan 1998|