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High-Visible-Light Photoactivity of Plasma-Promoted Vanadium Clusters on Nanozeolites for Partial Photooxidation of Methanol Mohamad El-Roz,*,† Louwanda Lakiss,† Igor Telegeiev,† Oleg I. Lebedev,‡ Philippe Bazin,† Aurelie Vicente,† Christian Fernandez,† and Valentin Valtchev† †
Normandie Université, ENSICAEN, UNICAEN, CNRS, Laboratoire Catalyse et Spectrochimie, 14050 Caen, France Normandie Université, ENSICAEN, UNICAEN, CNRS, Laboratoire CRISMAT, 14050 Caen, France
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S Supporting Information *
ABSTRACT: Cold VCl3−plasma is employed for the preparation of highly dispersed vanadium oxide clusters on nanosized zeolite. Different types of zeolites, such as EMT, FAU (z.X), and Beta, are used. The activity of the prepared catalysts is studied in the selective photooxidation of methanol under polychromatic visible and UV irradiations. The physicochemical properties and catalytic performance of plasma-treated zeolite Beta (P-V2O5@Beta) catalyst is compared with zeolite Beta (V2O5@Beta) and amorphous silica (V2O5@SiO2) impregnated vanadium oxide catalysts. Pure V2O5 is used as a reference material. The set of catalytic data shows that plasma-prepared zeolite Beta based catalyst displays the highest activity. Complementary characterization techniques including XRD, N2-sorption, FTIR, ionic exchange, pyridine adsorption, Raman, NMR, TPR, and EDX-TEM are used to study the impact of the preparation approach on the physicochemical properties and catalytic performance of photocatalysts. KEYWORDS: photocatalysis, zeolite, selective oxidation, methanol, vanadium oxide
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zeolite wafer (50−70 μm) situated in the middle of the reactor.8 The physicochemical analysis proved a high and homogeneous dispersion of titanium clusters in zeolite. A chemical interaction between the clusters and the support has been demonstrated, and a partial substitution of aluminum for titanium was observed.8 Synergetic enhancement of the accessibility and photocatalytic activity of the active sites with a decrease of the particles size ( 450 nm with respect to supported vanadium oxide based samples. The absorbance spectra of supported vanadium oxide samples are similar in the visible region, showing the presence of typical V2O5 species. However, in the UV region, two main bands at around 275 and 340 nm are clearly observed for the P-VOx@Beta sample. These bands are even more pronounced in the plasma treated sample with lower vanadium loading (
