EPR Studies of the Coverage Effects in TiO2(B)-Supported Vanadia Catalysts for Toluene Ammoxidation

Jansen, Susan (författare)

Tu, Yanping (författare)

Palmieri, Michael J (författare)

Sanati, Mehri (författare): Lund University,Lunds universitet,Ergonomi och aerosolteknologi,Institutionen för designvetenskaper,Institutioner vid LTH,Lunds Tekniska Högskola,Ergonomics and Aerosol Technology,Department of Design Sciences,Departments at LTH,Faculty of Engineering, LTH

Andersson, Arne (författare): Lund University,Lunds universitet,Avdelningen för kemiteknik,Institutionen för processteknik och tillämpad biovetenskap,Institutioner vid LTH,Lunds Tekniska Högskola,Division of Chemical Engineering,Department of Process and Life Science Engineering,Departments at LTH,Faculty of Engineering, LTH

(creator_code:org_t)

Elsevier BV, 1992
1992
Engelska.
Ingår i: Journal of Catalysis. - : Elsevier BV. - 1090-2694 .- 0021-9517. ; 138:1, s. 79-89

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Abstract Ämnesord

Stäng

EPR spectroscopy has been employed to determine the nature of vanadium (+4) species in the TiO2(B)-supported vanadia catalysts. IR and EPR studies show that multiple vanadia species are observed as a function of loading. At coverages greater than 3.5 theoretical layers, the EPR signal is reminiscent of bulk V205. At lower coverages, a different magnetic species dominates the resonance and may be attributable to tetrahedral states of vanadium at the oxide interface. The spin concentration and (g) suggest two distinct vanadia phases as a function of coverage. In this study, we have also analyzed catalysts after use in ammoxidation of toluene. These samples show strikingly different features compared with the freshly prepared samples. Changes in both the g-anisotropy and hyperfine coupling were observed relative to the fresh catalysts. Though EPR is not surface sensitive, inference into the nature of the catalytic surface can be made by comparison of catalysts of different coverage and studies of monolayer samples. A study of the TiO2(B)-vanadia interface was made by comparing monolayer catalysts prepared from slightly different technique. Our measurements show strikingly different features in V4+ species as a function of preparation.

Av författaren/redakt...: Jansen, Susan; Tu, Yanping; Palmieri, Michae ...; Sanati, Mehri; Andersson, Arne

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