SYNTHESIS, CHARACTERIZATION, AND CATALYTIC PROPERTIES OF SIO2-ATTACHED ONE-ATOMIC-LAYER NIOBIUM OXIDE CATALYSTS

One-atomic-layer niobium oxide catalysts were prepared on SiO2 surface by using two-stage attaching reactions between Nb(OC2H5)5 and silanols and were characterized by X-ray diffraction (XRD), electron probe microanalysis (EPMA), X-ray fluorescence (XRF), and extended X-ray absorption fine structure (EXAFS). The EXAFS analysis revealed the growth of one-atomic-layer niobium oxide structure on SiO2, showing the existence of Nb-Si bond at 0.327 +/- 0.003 nm. The niobium oxide one-atom layers on SiO2 were found to be more active and selective for C2H4 formation (intramolecular dehydration) from C2H5OH in the temperature range 373-573 K than a conventional impregnation Nb2O5/SiO2 catalyst and Nb2O5 bulk.