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Alumina-Titania Nanofibers Synthesis by pH Swing Method

Jose Antonio Muñoz Lopez, Esteban Lopez Salinas, Jose Antonio Toledo Antonio, and Jose Escobar Aguilar. Instituto Mexicano del Petroleo, Eje Central Lázaro Cárdenas No. 152 Col. San Bartolo Atepehuacan, Mexico, Mexico

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