Reactivity of monolayer V2O5 films on TiO2(110) produced via the oxidation of vapor-deposited vanadium

Abstract

The growth, and reactivity of monolayer V 2 O 5 films supported on TiO 2 (110) produced via the oxidation of vapor-deposited vanadium were studied using X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD). Oxidation of vapor-deposited vanadium in 10 -7 Torr of O 2 at 600 K produced vanadia films that contained primarily V +3 , while oxidation in 10 -3 Torr at 400 K produced films that contained primarily V +5 . The reactivity of the supported vanadia layers for the oxidation of methanol to formaldehyde was studied using TPD. The activity for this reaction was found to be a function of the oxidation state of the vanadium cations in the film. AbstractThe growth, and reactivity of monolayer V 2 O 5 films supported on TiO 2 (110) produced via the oxidation of vapor-deposited vanadium were studied using X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD).Oxidation of vapor-deposited vanadium in 10 -7 Torr of O 2 at 600 K produced vanadia films that contained primarily V +3 , while oxidation in 10 -3 Torr at 400 K produced films that contained primarily V +5 . The reactivity of the supported vanadia layers for the oxidation of methanol to formaldehyde was studied using TPD. The activity for this reaction was found to be a function of the oxidation state of the vanadium cations in the film.

Relating methanol oxidation to the structure of ceria-supported vanadia monolayer catalysts

“…Also, Wang and Madix have studied the interaction of methanol with vanadia supported on a TiO2(110) single crystal prepared by chemical vapor deposition of H2O and VOCl3 [52]. A more detailed study performed by Wong et al addressed the oxidation state of vanadia deposits and how the oxidation state relates to the reactivity [53]. From methanol-pre-covered vanadia containing V 3+ , FA desorbed at ~ 615 K, while for the fully oxidized V 5+ this temperature was significantly lower (~ 485 K).…”

A study of the electronic structure and reactivity of V/TiO2(110) with metastable impact electron spectroscopy (MIES) and ultraviolet photoelectron spectroscopy (UPS)

“…Vanadia supported on transition metal oxides is highly reactive for selective oxidation [1,2], selective catalytic reduction (SCR) of nitric oxide [3,4] and oxidative dehydrogenation (ODH) reactions [5,6]. In particular, vanadia supported on titania has attracted considerable interest with respect to understanding the role of the TiO 2 support and the active chemical state of the vanadia [7][8][9][10][11].…”

“…In particular, vanadia supported on titania has attracted considerable interest with respect to understanding the role of the TiO 2 support and the active chemical state of the vanadia [7][8][9][10][11]. The active form of a titania-supported vanadia catalyst consists of a monolayer or submonolayer of an oxidized vanadium species [2] where vanadium donates electrons to titania [11]. Adsorbed vanadium reduces Ti 4+ to Ti 3+ and is believed to disrupt the titania structure.…”

“…In particular the reactivity of alcohols has been shown to be sensitive to the structure and oxidation state of vanadia supported on titania in partial oxidation and dehydrogenation of alcohols [2,12]. The catalytic conversion of ethanol to ethylene is a route to transform biomass to ethylene, an important feedstock in the chemical industry.…”

“…In the present study, the adsorption and decomposition of ethanol were investigated on V/TiO 2 (110) by metastable impact electron spectroscopy (MIES), ultraviolet photoelectron spectroscopy (UPS) and temperature programmed desorption (TPD) with the goal of understanding the structure and oxidation state of vanadia supported on titania [2,12]. Since MIES is highly sensitive to the change in the adsorbate-induced density of states (DOS) [18][19][20], it is an ideal technique for the study of the electronic properties of metal oxide surfaces.…”