Continuous synthesis of high-surface-area aluminum hydroxide methoxide nano- and microparticles in supercritical methanol and their conversion into gamma-Al2O3

Abstract

High-surface-area aluminum hydroxide methoxide (CH4Al2O4) nano- and microparticles are synthesized continuously in supercritical methanol (scMeOH). The properties of the particle synthesized in scMeOH are compared with those synthesized in supercritical water (scH(2)O). The XRD analysis reveals that the particles synthesized in scMeOH retain aluminum hydroxide methoxide crystalline structure while the particles synthesized in supercritical water retain boehmite (AlOOH) crystalline structure. Plate-shape particles are synthesized in scH(2)O while highly porous, flake-like particles are synthesized in scMeOH. Due to the porous structure, the CH4Al2O4 particles have much higher BET surface area (314 m(2)/g) than that of the boehmite particles (35.9 m(2)/g). The FT-IR analysis indicates that aliphatic, carbonyl, and hydroxyl groups are present on the surface of the CH4Al2O4 particles. When heat treated at 800 degrees C, the CH4Al2O4 phase is converted to gamma-Al2O3 phase with a BET surface area of 164 m(2)/g. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.