A Removal Of Trace Silicon Impurity From Aluminum Isopropoxide

Aluminum isopropoxide [Al (OPri) 3] is an important precursor for preparing high-purity and nanometer alumina. Some special and potential applications of the alumina products have led to a further purification of this alkoxide. Iron and silicon are the key trace impurities in aluminum isopropoxide, which dramatically affect the photophysical properties of alumina-containing materials and obscure the other intrinsic properties, such as an abnormal grain growth of alumina stimulated by SiO2. An efficient elimination of trace iron from aluminum isopropoxide has been reported recently. Although silicon belongs to the most important impurity in aluminum isopropoxide, there are relatively few references in the literature regarding the removal of trace silicon impurity from this alkoxide system. In this paper, two sides will be shown:1. The method of removing trance silicon impurityAn unprecedented method is presented to remove the silicon impurity in aluminum isopropoxide. By interacting lanthanum oxide with the silicon impurity in aluminum isopropoxide, an involatile silicon-containing compound is formed. The mass ratio of lanthanum oxide and aluminum is 1:100 and the reactive time is only 6 h, the effect of removal of silicon is excellent. After a vacuum distillation the silicon content in aluminum oxide can be reduced from more than 60 ppm to less than 10 ppm.2. The reactive mechanism of silicon impurity in aluminum isopropoxideThe study suggests that the possible reactant in aluminum metal is Al-Si eutectoid. The silicon product may be Al-Si double alkoxide. The molecular formula of this double alkoxide has been supposed to be Al C Si(OPri)5 ) 3. These two results will be described and discussed.