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

• Published in: Materials research bulletin 1993-06, Vol.28 (6), p.575-590
• Main Authors: Aschwanden, S., Schmalle, H.W., Reller, A., Oswald, H.R.
• Format: Article
• Language: English
• ISSN: 0025-5408; 1873-4227
• DOI: 10.1016/0025-5408(93)90054-H

A new cobalt-ethylenediamine-vanadate [Co(en) 3] 3+ 2V 2O 7 4−HVO 4 2−·6H 2O has been synthesized and structurally characterized. The unit cell is triclinic, space group P1, a = 8.782(3) A ̊ , b = 8.967(3) A ̊ , c = 12.562(2) A ̊ , α = 89.89(2)°, β = 105.30(2)°, γ = 116.01(3)°, V = 850.1(3) A ̊ 3 , Z = 1. The thermal decomposition has been studied by thermogravimetry and simultaneous mass spectrometry (TG/MS) in different atmospheres, i.e. H 2, N 2 and O 2. As solid products elemental cobalt on V 2O 3, Co 2V 2O 7, Co 3V 2O 8 and VO x have been obtained, and depending on the actual atmosphere different volatile products such as NH 3, H 2O, NO and CO 2. Independent of the pretreatment, reoxidation of the product phases leads to the ternary oxides Co 2V 2O 7 and Co 3V 2O 8. 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.