SYNTHESIS OF COMPLEX OXIDES OF COBALT-NEODYMIUM FROM HETEROCOMPLEXES AND THEIR CATALYTIC ACTIVITY IN THE DE­COM­POSITION OF HYDROGEN PEROXIDE

Abstract

New heterometallic complexes of Сo(II) and Nd(III) with carboxylic acids (succinic, oxalic) and acetylacetone in the presence of phenanthroline or α,α'-dipyridyl have been synthesized. Their thermal properties and the ability to form complex oxides during thermal degradation have been studied. In the process of thermolysis of heterocomplexes, neodymium cobaltate NdCoO3 was obtained, which is confirmed by the results of X-ray powder diffraction. The research has established that the X-ray powder diffraction patterns of the products obtained by thermolysis of heterocomplex [Сo2Nd2(C4Н4O4)5·2Phen]·4Н2О to 1000 °С exhibits peaks at (2θ): 23.40, 33.74, 41.42, 48.32, 54.52, 59.94, 70.58°. This corresponds to the neodymium cobaltate NdCoO3. Neodymium cobaltate crystallizes in the cubic crystal system. The sample was obtained without extraneous phases inclusions. For the samples obtained by the termolysis of he­te­rocomplexes [Сo2Nd2(C2O4)5·2Phen]·4Н2О and NdCo(AA)5·2α,α'-dipy, in addition to the complex oxide NdCoO3, peaks of Nd2O3 were recorded, which crystallizes in the hexa­gonal crystal system. The X-ray powder diffraction patterns show peaks with 2θ values: 26.92, 29.75, 30.77, 40.54, 47.53, 53.63, 57.08°. The phase ratio of NdCoO3/Nd2O3 after termolysis for the sample of CoNd(AA)5·2α,α'-dipy is ~ 68.9/31.1%; for the sample of [Сo2Nd2(C2O4)5·2Phen]·4Н2О is ~ 50/50%; for the sample of [Сo2Nd2(C4Н4O4)5·2Phen]·4Н2О is NdCoO3 ~ 100%. The average crystallites size of complex oxides was calculated using the Scherer formula. It has been showed that neodymium cobaltate has an average particle size of ~33 nm, regardless of the complex precursor from which it was formed during thermolysis. The catalytic effect of neodymium cobaltates in the hydrogen peroxide decomposition reaction was studied. It was shown that all samples of complex oxides showed a quite high cataly­tic activity in the all of experiments in the hydro­gen peroxide decomposition reactions.