Thermal decomposition course of Eu(CH_3COO)_3·4H_2O and the reactivity at the gas/solid interface thus established

摘要

The thermal decomposition course of europium acetate tetrahydrate (Eu(CH_3COO)_3·4H-2O) was probed on heating up to 1000℃ in a dynamic atmosphere of air by thermogravimetry and differential thermal analysis. The solid- and gas-phase decomposition products were identified by X-ray diffractometry, ex-and in situ infrared spectroscopy and mass spectrometry. Results obtained showed the acetate to dehydrate stepwise at 145-283℃, and then decompose stepwise to yield eventually cubic-Eu_2C_3 at >663℃ encompassing the formation of intermediate oxycarbonate (Eu_2O(CO_3)_2/Eu_2O_2(CO_3) solid products (at 347-466℃)) and H_2O, (CH_3)_2CO and CO_2 as primary gaseous products. A considerable enhancement of the production of the primary gas phase products at 400-450℃ and the emergence of (CH_3)_2C=CH_2, CH_4 and CO molecules in the gas phase are ascribed to reactions occurring at the gas/solid interface at the expense of some of the primary products. These interfacial activities impart application-worthy adsorptive and catalytic functions for the associated solid products.