Document Type : Research Paper
Department of Chemical Technologies, Iranian Research Organization for Science and Technology (IROST), Tehran, I. R. Iran
In this study, preparation of nano-sized gamma alumina with high specific surface area and high yield by thereaction between aluminum nitrate and sodium carbonate, without using any surfactant is reported. Bohemite (Aluminum oxyhydroxide) was prepared as a precursor by strict control of pH and reaction temperature. The gel produced was purified by washing followed by centrifugation. The specific thermal program was applied for calcination. This resulted in a leaf flower shaped gamma alumina in 91% yield, with 413 m2/g specific surface area and average pore volume 1.624 cm3/g. The flower like micro sheets of gamma alumina contained spherical particles with an average size of about 38 nanometers. Elemental analysis and FTIR spectra showed that sodium and carbonate ion impurities were completely removed from the prepared gamma alumina. X-ray diffraction pattern and TG/DTA analysis confirmed that bohemite and gamma alumina phase were formed. XRD, SEM and BET data of synthesized catalyst were compared with commercial catalyst. Dehydration of methanol was conducted by the synthesized gamma alumina. The catalyst evaluations were performed at different temperatures and different weights hourly space velocities. The commercial catalyst and the synthesized catalyst were compared in this work and the results showed that the performance of nanosized catalyst was better than the commercial one.