The influence on SCR activity of the atomic structure of V2O5/TiO2 catalysts prepared by a mechanochemical method

A catalyst prepared by a mechanochemical method enables changes in physico-chemical properties such as surface area, particle size and phase. Accordingly, after preparing the catalyst by synthesizing V2O5 and anatase TiO2 with the mechanochemical method, a study on the selective catalytic reduction (SCR) reactive properties of NH3 was performed. The dry ball milling method was shown to be compatible with the dry synthesis method of the SCR catalyst by combining V2O5 and TiO2. The properties of the catalyst were studied using physio-chemical analyses, including BET surface area, X-ray diffraction (XRD), Raman spectroscopy, H2 temperature programmed reduction (H2-TPR), diffuse reflectance UV–VIS spectroscopy and X-ray photoelectron spectroscopy (XPS). The V2O5 crystallite peak decreased with increased milling time, and the monomeric species was formed. The maximum reducing temperature (Tmax) decreased by H2-TPR. Improvements in the redox capacity were identified by experiments in which O2 was introduced and subsequently removed as well as by reoxidation analysis. Additionally, the presence of non-stoichiometric vanadium and an increased number of surface atoms were identified through the milling effect. A correlation was identified between the ratio of (V4+ + V3+)/V5+ and the catalyst NOx conversion rate.

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► Dry ball milling method can be applied as a dry synthesis method of SCR catalyst.
► The structure of V species transformed from the crystallite V2O5 to monomeric.
► (V4+ + V3+)/V5+ ratio and NOx conversion have a proportional relationship.