Formation and surface characterization of thulium oxide catalysts

Thulium oxide, Tm2O3, was obtained as a final product of the thermal decomposition of Tm(CH3COO)(3). 4H(2)O. The decomposition steps up to 800 degrees C were characterized by TG, DTA, XRD, SEM, GC-MS and gas- and solid-phase IR spectroscopy. The results showed that Tm(CH3COO)(3). 4H(2)O dehydrates completely in two overlapping steps at 90 and 110 degrees C and decomposes to Tm2O3 at 540 degrees C through a non-crystalline intermediate Tm(OH)(CH3COO)(2) at 350 degrees C, Tm(O)(CH3COO) at 375 degrees C and Tm2O2CO3 at 400 degrees C. The oxides obtained at 600 and 800 degrees C were subjected to texture analysis and pyridine adsorption. The results revealed that the oxide obtained at 600 degrees C has a higher surface area of 49.7 g(-1) with larger pores than that obtained at 800 degrees C (S-BET=32.8 g(-1)). On the other hand, the oxide obtained at 600 degrees C has a basic surface character and contains at least two different Lewis acid sites as indicated from pyridine adsorption. The gaseous decomposition products as identified by gas-phase IR and GC-MS are water vapour, acetic acid, ketene, acetone and methane.