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

作者：Zamani S; Chiesa M; Meynen V; Xiao Y; Prelot B; Zajac J; Verpoort F; Cool P; Van Doorslaer S^*

来源：Journal of Physical Chemistry C, 2010, 114(30): 12966-12975.

DOI：10.1021/jp103794x

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 VO(2+) 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 (13)CO(2) and NH(3) to the vanadyl sites for both full-grown VS-1 and VS1-SBA15. Furthermore, two-cycle CO(2) and NH(3) adsorption experiments were performed. While the latter showed no chemisorption of CO(2) at 373 K for both materials, clear evidence was found for ligation of CO(2) to vanadyl in full-grown VS-1 by the detection of a strong (13)C hyperfine value. This strong binding was not detected for the vanadyl centers in VS1-SBA15. Chemisorption of NH(3) was detected for all samples both by two-cycle adsorption experiments and by EPR.

• 出版日期2010-8-5