Phase transition in niobium pentoxide supported on silica-alumina

• Published in: Journal of thermal analysis and calorimetry Vol. 92; no. 3; pp. 851 - 855
• Main Authors: Braga, V. S., Garcia, F. A. C., Dias, J. A., Dias, Sílvia C. L.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.06.2008; Springer
• Subjects: Analytical Chemistry; Catalysis; Catalysts: preparations and properties; Chemistry; Chemistry and Materials Science; Exact sciences and technology; General and physical chemistry; Inorganic Chemistry; Measurement Science and Instrumentation; Physical Chemistry; Polymer Sciences; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; supported catalyst; niobium pentoxide; phase transition; silica-alumina; thermal analysis; Thermogravimetry; Transition metal; Differential thermal analysis; X ray diffraction; Silica; Phase transitions; Supported catalyst; Aluminium Oxides; Niobium Oxides; Raman spectrometry; Thermal analysis; Alumina
• ISSN: 1388-6150; 1588-2926; 1572-8943
• DOI: 10.1007/s10973-006-8325-4

Nb 2 O 5 supported on SiO 2 -Al 2 O 3 were prepared with a wide loading range (2, 5, 10, 15, 20 and 25 mass%) and analyzed by simultaneous thermogravimetric (TG) and differential thermal analysis (DTA). The materials presented a phase transition close to 1364°C. This phase transition was studied by XRD, FTIR and Raman spectroscopy. Amixture of orthorhombic (T) andmonoclinic (H andM) crystalline phases was evidenced in the supported samples, which is coverage dependent, in contrast to the formation of only the monoclinic phase (H and M) when pure Nb 2 O 5 is heated under the same conditions. These results indicate the stabilization of Nb 2 O 5 on silica-alumina surface.