Thermal decomposition of ammonium vanadyl oxalate supported on various oxides

✍ Scribed by X.S. Li; L.Y. Chen; C.Y. Xie; Y.F. Miao; D.M. Li; Q. Xin

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 557 KB
• Volume: 260
• Category: Article
• ISSN: 0040-6031
• DOI: 10.1016/0040-6031(95)90484-0

✦ Synopsis

The thermal decomposition of ammonium vanadyl oxalate supported on La,O,, MgO, SiO,, Al,O,, ZrO,, TiO,, SAPO-5, and ZSM-5 oxides in a dynamic atmosphere of dry air was compared by thermal gravimetric analysis (TG) and differential thermal analysis (DTA). The calcined catalysts were characterized by X-ray diffractometry (XRD). The TG and DTA results demonstrate that the surface acid-base properties of the oxides play a significant role in the decomposition behaviour of the supported ammonium vanadyl oxalate, i.e. the basic oxides exhibit an endothermic effect and the acidic oxides show an exothermic effect. Two mechanisms are suggested for thermal decomposition of ammonium vanadyl oxalate on basic and acidic oxides, respectively.

After transformation of the ammonium vanadyl oxalate to vanadia, subsequent rearrangement of the vanadia on the surface of the supports was also observed. During the thermal treatment or calcination in air, solid state reactions of vanadia with the surface of oxides such as La,O,, ZrO, and TiO, took place to form new phases.