Preparation of alumina–titania nanofibers by a pH-swing method

• Published in: Catalysis today 2008-04, Vol.133, p.113-119
• Main Authors: Muñoz-López, José Antonio, Toledo, José Antonio, Escobar, José, López-Salinas, Esteban
• Format: Article
• Language: English
• Subjects: Alumina; Alumina–titania support; Nanofibers; pH-swing method
• ISSN: 0920-5861; 1873-4308
• DOI: 10.1016/j.cattod.2007.12.044

Fibrillar Al 2O 3–TiO 2 were obtained by a pH-swing method by varying the pH from 2 to 8, and repeating this range (e.g. a cycle) several times, in combination with different ways to incorporate titanium oxisulfate. Depending on the stage in which Ti-oxisulfate is added to the alumina, large anatase aggregates or very dispersed TiO 2 domains were obtained on/in alumina nanofibers. Thus, when using a co-precipitation method in combination with pH-swing between pH 2 and 8, with six pH cycles, a high TiO 2 dispersion can be obtained, as indicated by Raman spectroscopy and X-ray diffraction. On the other hand, when adding Ti-oxysulfate at the end of the pH-swing procedure, though alumina nanofibers were formed, anatase was predominantly located as large particles in the interfibrillar voids. Specific surface area and total pore volume of nanofibrillar Al 2O 3–TiO 2 were around 300 m 2/g and 1 cm 3/g, respectively, after calcining at 500 °C. The highly disordered intertwined fibrils favored high pore volume values, even upon calcinations at 500 °C.