Preparation and characterization of Keggin-type heteropolysalts, Co_xPMo₁₂O₄₀ (x = 0–1.5)

¹ Laboratoire de Chimie du Gaz Naturel, Faculté de Chimie, USTHB, BP. 32, El-Alia, 16111 Bab-Ezzouar, Alger, Algérie
² Département de Chimie, Faculté des Sciences, Université Mouloud Mammeri, Tizi-Ouzou, Algérie
³ ILV-UMR 8180 CNRS, Université de Versailles -St Quentin-en-Yvelines, Bâtiment Lavoisier, 45 avenue des Etats-Unis, 78035 Versailles Cedex, France

^a e-mail: tassa2002dz@yahoo.fr

Abstract

Polyoxometalates (POMs), based transition-metal oxide clusters, have received much attention in various fields such as catalysis, photochemistry, nonlinear optics, biology and medicine [1]. Their physico-chemical, acidic and oxidative properties can be adjusted according with the nature of constituent elements [2]. In the field of catalysis, the most studied POMs are those with the Keggin. They were tested in wide variety of reactions in homogeneous and heterogeneous phases. In the redox processes, the nature of counter- cation in the [PMo₁₂O₄₀]³⁻ system can play a significant role. Thus, it has been shown that using Fe(III), vanadyl(VO²⁺), antimony (Sb³⁺) or cobalt (Co²⁺) counter-cation develop a more favourable distribution of both reduced Mo(V) and oxidized Mo(VI) sites [3]. In the present work we report the synthesis and characterization using several techniques of Keggin-type heteropolysalts of composition H_3−2xCo_xPMo₁₂O₄₀(x = 0 − 1.5) denoted as Co_xPMo₁₂.