(347f) Alumina-Titania Nanofibers Synthesis by pH Swing Method

A pH-swing method to form fibrillar alumina by using six cycles of pH variation from 2 to 8, in combination with different ways to incorporate titanium oxide has been examined. Depending on the stage in which Ti is added to the pH-swing alumina, large anatase aggregates or very disperses TiO2 domains can be obtained on/in alumina nano-fibers. Thus, when using a coprecipitation method in combination with pH-swing between pH 2 and 8, with six pH cycles, a high TiO2 dispersion can be obtained, as indicated by Raman and DRX. On the other hand, when adding Ti at the end of the pH-swing cycles (six), though alumina nano-fibers are formed, anatase is predominantly located as large particles in the interfibrillar voids. Specific surface area and total pore volume of nanofibrilar Al2O3-TiO2 are around 330 m2/g and 1 cm3/g, respectively, after calcining at 500°C. The highly disordered intertwined fibrils favor high pore volume values, even upon calcinations at 500°C