日本ゼオライト学会　刊行物 Publication of Japan Zeolite Association

It is expected that nanosized zeolites with the primary particle size of less than 100 nm exhibit improved properties based on the large external surface area-to-volume ratios and reduced mass transfer resistance, compared with micron-sized and submicron-sized zeolites. Since A-type zeolites having the highest Al/Si molar ratio (Al/Si=1) show the highest cationic exchange capacity among various types of zeolites, they are widely used as cationic exchangers (detergent builders). Thus, their production is the most among various types of zeolites, indicating that A-type zeolites should be the most important zeolites in the viewpoint of the industrial application. Many attempts have been made to reduce the primary particle size of A-type zeolites because of their improved properties (cationic exchange rate). However, to the best of our knowledge, no report has been published on synthesis of nanosized A-type zeolites from common starting materials such as sodium silicates and sodium aluminates. Here, we present high concentration and high yield synthesis method of nanosized A-type zeolites from the common starting materials by using a nonionic surfactant and polyethylene glycol as crystallization inhibitors. In addition, we show that the nanosized A-type zeolites exhibit excellent cationic exchange properties (cationic exchange rate), which should be due to their smaller primary particle size (nano-size) and their larger external surface area-to-volume ratios.