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Development and characterization of thermally stable supported V–W–TiOcatalysts for mobile NH–SCR applications

Beale, AM; Lezcano-Gonzalez, I; Maunula, T; Palgrave, RG; (2015) Development and characterization of thermally stable supported V–W–TiOcatalysts for mobile NH–SCR applications. Catalysis, Structure & Reactivity , 1 (1) pp. 25-34. 10.1179/2055075814Y.0000000005. Green open access

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Abstract

Vanadium based catalysts supported on a mixture of tungsten and titanium oxide (V2O5/WO3–TiO2) are known to be highly active for ammonia selective catalytic reduction (NH3–SCR) of NOx species for heavyduty mobile applications. However they are also known to be sensitive to high temperatures which leads to both sintering of the anatase TiO2 support and a first order phase transition to rutile at temperatures .600uC. Here we report our attempts to use SiO2 to stabilize the TiO2 anatase phase and to compare its catalytic activity with that of a non-stabilized V2O5/WO3–TiO2 catalyst after thermal aging up to 800uC. Detailed characterization using spectroscopic (Raman, UV–vis, X-ray absorption spectroscopy), scattering and techniques providing information on the catalytic surface (Brunauer–Emmet–Teller, NH3 adsorption) have also been performed in order to understand the impact of high temperatures on component speciation and the catalytic interface. Results show that non-stabilized V2O5/WO3–TiO2 catalysts are initially stable after thermal aging at 600uC but on heating above this temperature a marked drop in catalytic activity is observed as a result of sintering and phase transformation of Anatase into Rutile TiO2 and phase segregation of initially highly dispersed WO3 and polymeric V2O5 into monoclinic WO3 and V2O3 crystallites. Similar behavior was observed for the 4–5 wt-% of SiO2-stabilised sample after aging above 700uC, importantly therefore, offset by some y100uC in comparison to the unstabilised sample.

Type: Article
Title: Development and characterization of thermally stable supported V–W–TiOcatalysts for mobile NH–SCR applications
Open access status: An open access version is available from UCL Discovery
DOI: 10.1179/2055075814Y.0000000005
Publisher version: http://dx.doi.org/10.1179/2055075814Y.0000000005
Language: English
Additional information: This is an Accepted Manuscript of an article published by Taylor & Francis in Catalysis, Structure & Reactivity on 3 October 2014, available online: http://www.tandfonline.com/10.1179/2055075814Y.0000000005.
Keywords: V–W–TiO2, NH3–SCR, Thermal deactivation, Stability, Spectroscopy
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry
URI: https://discovery.ucl.ac.uk/id/eprint/1473186
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