Thermal decomposition and creation of reactive solid surfaces: VI. thermal genesis course of titania catalyst from a novel ammonium titanyl oxalate precursor

Abstract

The thermal decomposition course of ammonium titanyl oxalate monohydrate (ATO), (NH 4) 2[TiO(C 2O 4) 2] · H 2O, was explored in view of its possible employment as a promising titania precursor in supported titania catalysts prepared by impregnation and subsequent calcination. The investigation implemented thermal analysis of ATO, and characterization of its gas and solid phase calcination products (at 100–800°C) by means of infrared spectroscopy and X-ray diffractometry, to elucidate the pathways of the solid state reactions involved. The results revealed the occurrence of four endothermic weight loss processes (at 145–290 ° C) leading to formation of amorphous (at ⩾ 200–300°C), anatase-structured (at 350–700 ° C) and rutile-structured (at ⩾ 800°C) titania, via weight-invariant exothermic processes (maximized at 337, 408 and 773°C). Non-isothermal kinetic parameters ( k, A and Δ E) were calculated on the basis of the temperature shifts experienced at various heating rates (5, 10, 20 and 30 °C min −1) by the thermal events encountered.