PREPARATION, CRYSTAL-STRUCTURE AND THERMAL-BEHAVIOR OF COBALT-ETHYLENEDIAMINE-VANADATE

A new cobalt-ethylenediamine-vanadate [Co(en)3]3+2V2O74-HVO42-.6H2O has been synthesized and structurally characterized. The unit cell is triclinic, space group P1, a = 8.782(3) angstrom, b = 8.967(3) angstrom, c = 12.562(2) angstrom, alpha = 89.89(2)-degrees, B = 105.30(2)-degrees, gamma = 116.01(3)-degrees, V = 850.1(3) angstrom3, Z = 1. The thermal decomposition has been studied by thermogravimetry and simultaneous mass spectrometry (TG/MS) in different atmospheres, i.e. H-2, 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.