Thermoanalytical study of vanadyl and vanadium acetoacetonates

Abstract

The thermal decomposition reactions of vanadyl and vanadium acetoacetonates in dry nitrogen have been thoroughly studied. Thermal processes occurring throughout the decomposition range (100–500°C) were monitored by means of TG, DTA and IR spectroscopic analysis of the gaseous products. These processes were characterized on the basis of the solid product analyses using X-ray diffractometry and IR spectroscopy. The results showed that VO(C 5H 7O 2) 2 had completely decomposed to V 2O 3 at 325°C through the intermediates VO(CH 3COO)(C 5H 7O 2) at 290°C, VO(CH 3COO) 2 at 300°C and V 2O(CO 3) 2 at 315°C. In contrast, V(C 5H 7O 2) 3 decomposed via the acetate at 280°C and the carbonate at 292°C as intermediates. The carbonate decomposed immediately to give V 2O 5 at 305°C. Part of the V 2O 5 underwent a reduction process through an endothermic effect at 325°C. The ultimate solid products at 400°C were V 2O 3 and V 2O 5. Gas phase products included propyne, acetone, carbon oxides, methane and isobutene. Methane and isobutene resulted from interfacial reaction involving the initial product (acetone).