Surface species structure and activity in NO decomposition of an anatase-supported V–O–Mo catalyst

• Published in: Catalysis today Vol. 137; no. 2; pp. 273 - 277
• Main Authors: Kornelak, P., Su, D.S., Thomas, C., Camra, J., Wesełucha-Birczyńska, A., Toba, M., Najbar, M.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 30.09.2008; Elsevier Science
• Subjects: Anatase-supported V–O–Mo catalyst; Catalysis; Chemistry; Exact sciences and technology; General and physical chemistry; NO decomposition; Surface interstitial V ions; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Vanadia surface species; Surface interstitial V ions; Anatase-supported V–O–Mo catalyst; Vanadia surface species; NO decomposition; Nitrogen oxide; Air pollution control; Anatase; Support; Transition element compounds; Ions; Decomposition; Surface structure; Chemical reduction; Heterogeneous catalysis; Anatase-supported V-O-Mo catalyst; Vanadium oxide; Catalyst; Environmental protection
• ISSN: 0920-5861; 1873-4308
• DOI: 10.1016/j.cattod.2008.03.002

The paper concerns the evolution of surface species of a V–O–Mo/anatase catalyst in the course of its thermal treatment in oxidising and/or reducing conditions. The catalyst was obtained by the sol–gel method. The structure of its surface was investigated by XPS and Raman spectroscopy. The fresh catalyst consists of anatase nanocrystallites with some vanadium and molybdenum ions substituted for titanium ones and molybdenum oxide islands on their surfaces. A V/Mo 5O 14 solid solution-containing V atoms in its channels, as well as MoO 3 and anatase with some surface vanadia species are present on the catalyst surface. The reduction of anatase to TiO 2− x and of MoO 3 to Mo 5O 14, accompanied by inward vanadium diffusion occurs during the catalyst interaction with ammonia at 523 K. The oxidation of the TiO 2− x but not Mo 5O 14 and V reappearance in the surface channels take place during the interaction of the reduced catalyst with molecular oxygen. However, the oxidation of Mo 5O 14 to MoO 3 occurs under the influence of atomic oxygen, formed by NO decomposition at 423 K. It is accompanied by the surface vanadia species formation. The activity of V ions of these species in NO decomposition is lower than of the surface interstitial ones.