Synthesis of nano-fibers of aluminum hydroxide in novel rotating packed bed reactor

This paper presents a route of synthesizing nano-fibrillar aluminum hydroxide (AH) by carbonation in a novel rotating packed bed (RPB) reactor and thermal hydrolysis. Carbonation of sodium aluminate (SA) is conducted by introducing CO2 into RPB at room temperature to form AH gel which is subsequently treated by thermal hydrolysis for an optimum time of 30 min and temperature of 85(degree)C to yield nano-fibrillar pseudoboehmite (PB) of 1–10 nm in diameter and 50–300 nm in length. Factors affecting carbonation process such as high gravity level, Gas/Liquid ratio and SA solution concentration are discussed. Experimental results reveal that operating conditions have significant influences on the properties of PB and the morphology of PB is closely related to the unit structure of AH gel. The as-prepared PB is characterized by TEM and XRD and compared with those synthesized by conventional Stirred Tank Reactor (STR). Reaction time in RPB shortens for approximately a half compared with that in STR. It is proven that this route has obvious advantages over STR.