Effect of vanadia on physico-chemical and catalytic characteristics of dysprosia

Abstract

<span style="font-size:16.0pt;mso-bidi-font-size:12.0pt" lang="EN-IN">Physico-chemical characterization of <span style="mso-bidi-font-style:italic">Dy₂O₃/V₂O₂ systems prepared through wet impregnation method has been carried out using various techniques like EDX, XRD, FTIR, thermal studies, BET surface area, pore volume and pore size distribution analysis. The amount of vanadia incorporated has been found to influence the surface properties of dysprosia. The spectroscopic results combining with X-ray analysis reveal that vanadia species exist predominantly as isolated amorphous vanadyl units along with crystalline dysprosium orthovanadate. Basicity studies have been conducted by adsorption of electron acceptors and acidity and acid strength distribution by temperature programmed desorption of ammonia. Cyclohexanol decomposition has been employed as a chemical probe reaction to examine the effect of vanadia on the ac id base property of <span style="mso-bidi-font-style:italic">Dy₂O₃. Incorporation of vanadia titrates the Lewis ac id and base sites of <span style="mso-bidi-font-style:italic">Dy₂O₃, while an enhancement of Bronsted acid sites has been noticed. Data have been correlated with the catalytic activity of these oxides towards the vapour phase methylation of phenol.

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