Coupling of the deoxygenation of benzoic acid with the oxidation of propylene as a new tool to elucidate the architecture of Mo-based oxide catalysts

• Main Author: Dury, Frédéric
• Format: Others
• Language: en
• Published: Universite catholique de Louvain 2005
• Subjects: Characterization; Active site; Benzoic acid; Propylene; Oxidation
• Online Access: http://edoc.bib.ucl.ac.be:81/ETD-db/collection/available/BelnUcetd-11222005-193414/

This work aimed to develop in a two-step strategy the deoxygenation of benzoic acid as a new probe reaction of the oxidation catalysts "at work". This choice was based on the experimental fact that the distribution of the potential main products, namely benzaldehyde, toluene and benzene depends on the presence and the mutual disposition of oxygen vacancies at the surface of the oxide catalysts. Indeed, it is claimed in the literature that single oxygen vacancies selectively produces benzaldehyde, twin oxygen vacancies (i.e. two oxygen vacancies separated by about 2Å) induce the formation of toluene while the benzene production does not need the presence of any oxygen vacancies. Two molybdenum based catalytic systems were chosen to test the new probe reaction : the molybdenum (sub)oxides and the metal molybdates. By the way of a new and original coupling between the probe reaction and the oxidation of propylene, we planned to correlate in real time the formation of the superficial oxygen vacancies monitored by the deoxygenation of benzoic acid and the activity in an oxidation reaction. Such an experimental coupling is a promising and a powerful tool which allows the fine characterization of the active catalytic site at work in an oxidation reaction.