Preparation, crystal structure and thermal behaviour of cobalt-ethylenediamine-vanadate

Article abstract of DOI:10.1016/0025-5408(93)90054-H

A new cobalt-ethylenediamine-vanadate [Co(en)₃]³⁺₂V₂O₇^4- HVO₄^2-·6 H₂O has been synthesized and structurally characterized. The unit cell is triclinic, space group P1, a = 8.782(3) angstroms, b = 8.967(3) angstroms, c = 12.562(2) angstroms, α = 89.89(2)°, β = 105.30(2)°, γ = 116.01(3)°, V = 850.1(3) angstroms³, Z = 1. The thermal decomposition has been studied by thermogravimetry and simultaneous mass spectrometry (TG/MS) in different atmospheres, i.e. H₂, N₂ and O₂. As solid products elemental cobalt on V₂O₃, Co₂V₂O₇, Co₃V₂O₈ and VO_x have been obtained, and depending on the actual atmosphere different volatile products such as NH₃, H₂O, NO and CO₂. Independent of the pretreatment, reoxidation of the product phases leads to the ternary oxides Co₂V₂O₇ and Co₃V₂O₈. The microstructures have been studied by scanning electron microscopy (SEM). The product formed in hydrogen has been tested with respect to its catalytic activity for the reduction of NO with CO.