Structure, Stability, Electrochemical and catalytic properties of polyoxometalates 1 immobilized on choline-based hybrid mesoporous silica

Abstract

Polyoxometalate-based heterogeneous catalysts have been prepared by immobilization 12 of Keggin-type heteropolyacid on hybrid mesoporous silica nanoparticles with choline 13 hydroxide based ionic liquid. The immobilization process has been accomplished by a 14 simple acid-base reaction with phosphomolybdic acid. For comparison purposes, 15 additional supports (hybrid-SBA-15 and TiO2) have been also used in order to establish 16 the nature of the interactions between the heteropolyacid and the surface’s groups of 17 the support. To do this, electrochemical and 31P MAS-NMR studies have been carried 18 out finding the formation of moieties like (Chol)2[HPMo12O40] and/or (Chol)3[PMo12O40] 19 on the silica materials. Polyoxometalate-based heterogeneous catalysts have been 20 effectively tested for the oxidative desulfurization of DBT in model oil. Thus, complete 21 removal of sulphur (99.7 %) was achieved with polyoxometalate supported on the silica 22 after 2 h and using H2O2 as a green oxidant. Additionally, reusability and stability studies 23 of the most active catalyst have been performed.