Abstract: Under the guide of ternary diagram of AlCl3 —Al2O3—H2O, two new polyaluminum compounds which conformed as AlCl3•4Al(OH)3•7.5H2O and AlCl3•7Al(OH)3•18H2O have been made with aluminum powder, aluminum chloride and distilled water. According to adjusting the reaction temperature, configuration of raw materials and degree of basification, after evaporating and crystallizing, the polyaluminum acquired. The polyaluminum chloride is characterized by means of XRD, chemical analysis and IR. The aluminum hydrolysis process has been investigated using chemical analysis as the main testing method, we discovered that temperature plays an important part in the formation of products and its properties, at the same time, the change of reaction with the change of temperature is a reversible process. The experiment further proved that the optimal formation temperature of AlCl3•4Al(OH)3•7.5H2O and AlCl3•7Al(OH)3•18H2O is 75℃，the productivity rate of products were higher at this temperature and the crystallizability were better.

Key words: hydrolytic polymeric aluminum, Al5, Al9, synthesis, characterization