RMN du 31P et mesure du temps de relaxation de l'acide 12-tungstophosphorique incorporé par synthèse directe dans une charpente silicique mésoporeuse

The catalytic function of heteropoly compounds has attracted much attention because of their variety and high potential as catalysts. Supported heteropoly acids are generally prepared by impregnation of the active phase by a solution. In this work, we present a new concept for the preparation of a new solid catalyst by direct incorporation of tungstophosphoric species (HPW) into organized mesoporous silica. Synthesis of organized mesoporous silica containing PW was carried out with a mixture of two surfactants, a non ionic one and a cationic one. Taking into account the instability of the tungstophosphate species, the pH domain was restricted to 4-6. The presence of PW species incorporated in the solids was evidenced by solid state 31P NMR. The relaxation times of these solids indicate a weaker mobility of PW in comparison with the impregnated ones.