Assessment of textural consequences on products of thermal decomposition of samarium acetylacetonate

Abstract

Textural consequences of the thermal decomposition of Sm(C 5H 7O 2) 3·2H 2O in dry nitrogen have been assessed by the analysis of nitrogen sorption isotherms, measured at −196°C, for their decomposition products obtained at different temperatures (300, 450 and 800°C), using a number of widely accepted methods. Sunsequently, a correlation was made of the results with physicochemical properties of the decomposition products and with the processes occurring during the course of the decomposition reaction. Thermal processes occurring throughout the decomposition range (100–800°C) were monitored by thermogravimetry, differential thermal analysis and infrared (IR) spectroscopic analysis of the gaseous products. These processes were characterized on the basis of the solid products analyzed using X-ray diffractometry and IR spectrometry. The results showed that Sm(C 5H 7O 2) 3 had completely decomposed to Sm 2O 3 at 750°C, via the amorphous and unstable intermediates Sm(CH 3COO)(C 5H 7O 2) 2 at 150°C, Sm(CH 3COO) 2(C 5H 7O 2) at 235°C, Sm(CH 3COO) 3 at 270°C, Sm 2O(CH 3COO) 3 at 500°C and Sm 2O 2(CO 3) at 650°C. The gases evolved in the gas phase included propyne, acetone, carbon oxides, methane and isobutene. Methane and isobutene resulted from an interfacial reaction involving the initial product (acetone). The final solid product Sm 2O 3 at 800°C is a crystalline porous material, having a surface area of 47 m 2 g −1.