Supported vanadium oxide in heterogeneous catalysis: elucidating the structure–activity relationship with spectroscopy

Abstract

In order to design the next generation of catalysts, it is crucial that the insights of researchers in heterogeneous catalysis, materials design and spectroscopy are merged. Since the scientific community started to realize that the molecular pattern of a catalyst at room temperature and in vacuum does by no means reflect the actual structure of the catalytic species under working conditions, new spectroscopic techniques have been developed to study the catalytic species "while doing the job" or in Latin, "operando". In this contribution, we give an overview of recent developments in-at first sight-the simple case of supported VO(x) species. In the last few years, many issues on the nature of the active sites in supported VO(x) species have been questioned again, and the observations and conclusions summarized in this paper present a clear case of the importance of structure-activity relationships in rational catalyst design.

Atomic Layer Deposition of Titanium and Vanadium Oxide on Mesoporous Silica and Phenol/Formaldehyde Resins – the Effect of the Support on the Liquid Phase Epoxidation of Cyclohexene

“…This observation is in agreement with general perspectives about supported metal oxide catalysts. [25,26] The reaction mechanism for the FDU-15-supported catalysts is depicted in Scheme 3 (b). Here, the metal oxide centres are supposed to be covalently bound by one single bond (or a double bond at most) as the hydroxyl-group density is lower than on the hydrophilic silica surface.…”

An IR spectroscopy assessment of the surface acidity of mesoporous VO –SiO2 catalysts

“…Supported vanadium oxides (VO x ) have also been studied as catalysts for many other reactions, such as methanol or carbon monoxide oxidation, volatile organic compounds decomposition, partial oxidation of hydrocarbons and ODH (Oxidative De-Hydrogenation) of light alkanes [1][2][3][4]. In particular, the latter reaction offers a potential alternative route to olefins production, because the overall reaction pathway is exothermic and the thermodynamic constraints of non-oxidative pathways are overcome [5][6][7][8].…”

“…Such reactive species are not observed with V-containing SBA-15: this could be IR difference spectra concerning NH 3 adsorption at r.t. on sample V-MCF outgassed at 150°C (a) and 500°C (b). IR difference spectra of NH3 adsorbed at r.t. on sample V-MCF-i outgassed at 500°C (c). (a-c): NH 3 equilibrium pressure in the range: 0.010-20.0 mbar.…”

Role of dispersion of vanadia on SBA-15 in the oxidative dehydrogenation of propane

“…[8] Complementary research has focused on the geometric structure of supported vanadia catalysts and especially how structure can be related to catalytic performance. [9][10][11][12] Despite all this effort, the exact nature of the active site remains the topic of controversial discussions.…”