459971 Olefin Metathesis By Supported WOx/SiO2 Catalysts

Thursday, November 17, 2016: 2:50 PM
Franciscan B (Hilton San Francisco Union Square)
Soe Lwin1,2 and Israel E. Wachs2, (1)Idaho National Laboratory, Idaho Falls, ID, (2)Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, PA

The kinetics of propylene metathesis by supported WOx/SiO2 catalysts were studied using in situ XAS (XANES/EXAFS), temperature programmed surface reaction (TPSR) and steady-state experiments. The in situ XAS experiments with well-defined catalysts provide information about the reducibility of different WOx phases (surface dioxo and mono-oxo WOx species and WO3 crystalline nanoparticles). Various TPSR experiments and steady-state partial pressure experiments allow for derivation of kinetic equations and determination of important kinetic parameters. Although WO3 crystals are more reducible upon contact with olefins, and thus reduce desorption activation energy (Ed), they do not contribute to metathesis reactivity and increase apparent activation energy (Eapp). The steady-state propylene partial pressure experiments show the first-order dependence of reactivity on propylene partial pressure. This is also confirmed by C3= or C2=/C4 TPSR experiments which provide the same peak temperature (Tp) value. Ethylene (C2=) cannot create sites unlike propylene (C3=) or 2-butene (C4=).

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See more of this Session: Catalytic Hydrocarbon Processing
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