The Novel and Effective Method of Removing of Trace Iron Impurity from Aluminum Isopropoxide for Nano-alumina

Aluminum isopropoxide (AIP) is an important precursor in preparing high-purity and nano-alumina. The iron impurity in AIP has bad effect on the application of nano-alumina. In order to prepare the iron-free AIP, chelate organic ligand is added to this reaction system together with Al and isopropanol to form the high boiling point complex of the iron impurity in AIP by chelation. It has been revealed that phenolphthalein (P), an O-containing organic ligand, can form a stable, non-volatile chelate complex with iron element in the presence of AIP. By adding P into the reaction system and undergoing vacuum distillation after the reaction, 80% of the total product gives a high purity value with Fe content being less than 10 ppm (by Al₂O₃) that satisfies the need of luminous materials when mass ratio of P: Al is 1:500. A feasible mechanism about removal of trace iron impurity from AIP has been presented.