Mechanochemical synthesis of double vanadate in Cu–Fe–V–O system and its physicochemical and catalytic properties

Mechanochemical synthesis has been successfully employed to prepare a Cu3Fe4(VO4)6 powder. The formation of designed compound (in α-polymorphic form) is due to the reactions of copper, iron and vanadium oxide precursors which were activated by high-energy ball milling (Activator 2S, Novosibirsk, Russia) for 8 h instead of heat energy required in the conventional multi-stage high-temperature process during 80 h forming β-polymorphic form.Catalytic properties of Cu3Fe4(VO4)6 compound, which has been prepared by two different mentioned above techniques, tested in the methanol steam reforming reaction are satisfactory and closely the same. However, α-, as well as, β-polymorphic forms of Cu3Fe4(VO4)6 are structural unstable during steam reforming of methanol and form a metallic copper beside V2O3 and iron oxides, which probably catalyze simultaneously undesired methanation reaction. The real chemical mechanism is still not clear.