Catalysts 2013, 3(4), 978-997; doi:10.3390/catal3040978
Article

Investigation of the Deactivation Phenomena Occurring in the Cyclohexane Photocatalytic Oxidative Dehydrogenation on MoOx/TiO2 through Gas Phase and in situ DRIFTS Analyses

Received: 16 August 2013; in revised form: 13 September 2013 / Accepted: 10 December 2013 / Published: 13 December 2013
(This article belongs to the Special Issue Advances in Catalyst Deactivation)
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: In this work, the results of gas phase cyclohexane photocatalytic oxidative dehydrogenation on MoOx/SO4/TiO2 catalysts with DRIFTS analysis are presented. Analysis of products in the gas-phase discharge of a fixed bed photoreactor was coupled with in situ monitoring of the photocatalyst surface during irradiation with an IR probe. An interaction between cyclohexane and surface sulfates was found by DRIFTS analysis in the absence of UV irradiation, showing evidence of the formation of an organo-sulfur compound. In particular, in the absence of irradiation, sulfate species initiate a redox reaction through hydrogen abstraction of cyclohexane and formation of sulfate (IV) species. In previous studies, it was concluded that reduction of the sulfate (IV) species via hydrogen abstraction during UV irradiation may produce gas phase SO2 and thereby loss of surface sulfur species. Gas phase analysis showed that the presence of MoOx species, at same sulfate loading, changes the selectivity of the photoreaction, promoting the formation of benzene. The amount of surface sulfate influenced benzene yield, which decreases when the sulfate coverage is lower. During irradiation, a strong deactivation was observed due to the poisoning of the surface by carbon deposits strongly adsorbed on catalyst surface.
Keywords: cyclohexane; gas phase analysis; DRIFTS analysis; deactivation
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MDPI and ACS Style

Vaiano, V.; Sannino, D.; Almeida, A.R.; Mul, G.; Ciambelli, P. Investigation of the Deactivation Phenomena Occurring in the Cyclohexane Photocatalytic Oxidative Dehydrogenation on MoOx/TiO2 through Gas Phase and in situ DRIFTS Analyses. Catalysts 2013, 3, 978-997.

AMA Style

Vaiano V, Sannino D, Almeida AR, Mul G, Ciambelli P. Investigation of the Deactivation Phenomena Occurring in the Cyclohexane Photocatalytic Oxidative Dehydrogenation on MoOx/TiO2 through Gas Phase and in situ DRIFTS Analyses. Catalysts. 2013; 3(4):978-997.

Chicago/Turabian Style

Vaiano, Vincenzo; Sannino, Diana; Almeida, Ana R.; Mul, Guido; Ciambelli, Paolo. 2013. "Investigation of the Deactivation Phenomena Occurring in the Cyclohexane Photocatalytic Oxidative Dehydrogenation on MoOx/TiO2 through Gas Phase and in situ DRIFTS Analyses." Catalysts 3, no. 4: 978-997.

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