THERMAL-DECOMPOSITION OF HOLMIUM OXALATE HEXAHYDRATE AND FORMATION OFA CATALYST FOR 2-PROPANOL DECOMPOSITION - THERMOANALYTICAL AND IN-SITU SPECTROSCOPIC STUDIES

Thermal events involved in the decomposition course of Ho-2(C2O4)3.6H( 2)O at 900 degrees C in air were monitored by nonisothermal gravimetry and differential thermal analysis at various heating rates. Determina tion of the corresponding activation energy values was thus facilitate d. Intermediate and final solid-phase products were characterized by X -ray diffractometry and infrared spectroscopy. The results indicated t hat following a stepwise dehydration at 100-400 degrees C, the product was noncrystalline and unstable to further heating. An oxycarbonate ( Ho2O2CO3) was obtained at 450 degrees C which decomposed near 600 degr ees C into crystalline Ho2O3 The oxide proportion and crystallinity im proved on increasing the temperature up to 900 degrees C. The oxide pr oduced at 900 degrees C was subjected to a preliminary test as a catal yst for the decomposition of 2-propanol vapor at 100-400 degrees C. Th e reaction gas phase was analyzed both qualitatively and quantitativel y using in situ infrared spectroscopy. The result revealed that Ho2O3 is a dual functioning catalyst at greater than or equal to 200 degrees C, and that the alcohol decomposes thereon via dehydration into prope ne (major product) and dehydrogenation into acetone. At greater than o r equal to 350 degrees C, the acetone was used up in a secondary surfa ce reaction, giving rise to gas phase CH4 and CO2.