American Chemical Society
jp103794x_si_001.pdf (501.81 kB)

Accessibility and Dispersion of Vanadyl Sites of Vanadium Silicate-1 Nanoparticles Deposited in SBA-15

Download (501.81 kB)
journal contribution
posted on 2010-08-05, 00:00 authored by S. Zamani, M. Chiesa, V. Meynen, Y. Xiao, B. Prélot, J. Zajac, F. Verpoort, P. Cool, S. Van Doorslaer
Vanadium silicalite-1 (VS-1) nanoparticles dispersed onto the mesoporous walls of SBA-15 silica have characteristics different from those of the full-grown VS-1. In particular, the vanadium-binding site differs extensively. Here, we monitor the local environment of VO2+ with different electron paramagnetic resonance (EPR) techniques to obtain information about the heterogeneity of the vanadyl sites, the effect of a calcination/reduction cycle, and the subsequent adsorption of 13CO2 and NH3 to the vanadyl sites for both full-grown VS-1 and VS1-SBA15. Furthermore, two-cycle CO2 and NH3 adsorption experiments were performed. While the latter showed no chemisorption of CO2 at 373 K for both materials, clear evidence was found for ligation of CO2 to vanadyl in full-grown VS-1 by the detection of a strong 13C hyperfine value. This strong binding was not detected for the vanadyl centers in VS1-SBA15. Chemisorption of NH3 was detected for all samples both by two-cycle adsorption experiments and by EPR.