Water-soluble niobium peroxo complexes as precursors for the preparation of Nb-based oxide catalysts

In the frame of research aimed at developing new synthetic procedures of multimetallic Nb-based catalysts, peroxo complexes of niobium(V) of general formula A(3)(I)[Nb(O-2)(4)] and A(3)(I)[Nb(O-2)(x)(HyL)].nH(2)O (A(I): NH4+, CN3H6+ (gu); L: oxalate, tartrate, citrate) have been prepared and characterized on the basis of elemental and thermal analysis, FTIR and C-13-NMR spectra. The crystal structure of (gu)(3)[Nb(O-2)(4)] and (gu)(3)[Nb(O-2)(2)(C2O4)(2)].2H(2)O have been determined. The application of the obtained Nb complexes as precursors for the preparation of silica-supported Nb-Mo-O catalysts has been demonstrated. Combining Nb peroxo-carboxylato compounds with analogous Mo(VI) compounds in a silica-impregnation method carried out in aqueous medium leads to the formation of the supported Nb2Mo3O14 phase. (C) 2002 Elsevier Science B.V. All rights reserved.