2019-Sustainable Industrial Processing Summit
SIPS2019 Volume 10: Vayenas Intl. Symp. / Physical Chemistry and its applications for sustainable development

Editors: Vayenas Intl. Symp. / Physical Chemistry and its applications for sustainable development Edited by: F. Kongoli, E. Aifantis, C. Cavalca, A. de Lucas Consuegra, A. Efstathiou, M. Fardis, D. Grigoriou, A. Lemonidou, S.G. Neophytides, Y. Roman, M. Stoukides, M. Sullivan, P. Vernoux, X. Verykios, I. Yentekakis
Publisher:Flogen Star OUTREACH
Publication Year:2019
Pages:249 pages
ISBN:978-1-989820-09-4
ISSN:2291-1227 (Metals and Materials Processing in a Clean Environment Series)
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    Characterization of WOx-ZrO2/MWCNT: An Aqueous Phase Acid Catalyst for Alcohol Dehydration

    Patrick Kelleher1; Cyril Thomas2; Hui Shi3; Gary Haller1;
    1YALE UNIVERSITY, New Haven, United States; 2SORBONNE UNIVERSITé, Paris, France; 3DEPARTMENT OF CHEMISTRY, CATALYSIS RESEARCH CENTER, TECHNISCHE UNIVERSITäT MüNCHEN, Garching, Germany;
    Type of Paper: Regular
    Id Paper: 32
    Topic: 53

    Abstract:

    Tungstated zirconia supported on multi-walled carbon nanotubes (WOx-ZrO2/MWCNT) has been characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), NOx temperature programmed desorption (NOx-TPD) and probe reaction of cyclohexanol dehydration in liquid water. TEM and XRD establish that the ZrO2 grafted to MWCNT are tetragonal crystalline nanoparticles of about 2 nm [1]. XAS and thermal gravimetric analysis indicates that the tungstated zirconia nanoparticles are hydrothermally stable at 200°C and NOx-TPD [2] was used to measure the interaction of impregnated WOx with ZrO2/MWCNT; the WOx preferentially interacts with the surface of ZrO2 until about a monolayer (~4 W/nm2) of coverage is reached when a WO3 particulate phase develops. At a coverage of 8 W/nm2, WO3 can be detected by XRD. The turnover frequencies (TOF) normalized per W atom for cyclohexanol dehydration at 215°C at W surface densities of 2, 4 and 8 W/nm2 are 0.043, 0.029 and 0.027, respectively, compared to a commercial bulk WOx-ZrO2 with W surface density of 5 W/nm2, where it is 0.021. Thus, the TOF of the WOx-ZrO2/MWCNT at 2 W/nm2 is about twice that of unsupported WOx-ZrO2 and exceeds the bulk WOx-ZrO2 even when the W density is greater than that of unsupported WOx-ZrO2. Dividing the bulk 15.5 wt% WOx-ZrO2 TOF (based on acid site density) by the TOF (based on a W atom normalization) indicates that on average it requires 3.3 W atoms per acid site. Because the acid site is a hydronium ion in all cases [3], a better interpretation is that fewer W atoms per acid site are required on the low W density WOx-ZrO2/MWCNT. Thus we estimate that about 1.6 W atoms per acid site are required on the 2 W/nm2 WOx-ZrO2/MWCNT.

    Keywords:

    Multi-walled carbon nanotubes; Tungstated zirconia; Liquid phase acid catalysis

    References:


    [1] C. Lui, S. Lee, D. Su et al., J. Phys. Chem. C, 116 (2012) 21742.
    [2] H. Y. Law, J. Blanchard, X. Carrier et al., J. Phys. Chem. C, 114 (2010) 9731.
    [3] H. Shi, S. Eckstein, A. Vjunov et al., nature Commun., 8 (2017) 15442.

    Cite this article as:

    Kelleher P, Thomas C, Shi H, Haller G. (2019). Characterization of WOx-ZrO2/MWCNT: An Aqueous Phase Acid Catalyst for Alcohol Dehydration. In Vayenas Intl. Symp. / Physical Chemistry and its applications for sustainable development Edited by: F. Kongoli, E. Aifantis, C. Cavalca, A. de Lucas Consuegra, A. Efstathiou, M. Fardis, D. Grigoriou, A. Lemonidou, S.G. Neophytides, Y. Roman, M. Stoukides, M. Sullivan, P. Vernoux, X. Verykios, I. Yentekakis (Eds.), Sustainable Industrial Processing Summit SIPS2019 Volume 10: Vayenas Intl. Symp. / Physical Chemistry and its applications for sustainable development (pp. 220-221). Montreal, Canada: FLOGEN Star Outreach