04-O-02-Preparation and catalytic properties of a novel type of zeolites with basic properties

Abstract

Publisher Summary This chapter discusses the preparation and catalytic properties of a novel type of zeolites with basic properties. Novel basic zeolite catalysts are obtained by the ammonia treatment of crystalline, microporous aluminosilicates at temperatures from 700°C to 900°C. The resulting materials are active catalysts in the Knoevenagel condensation of benzaldehyde with malononitrile, presumably because of the presence of nitrogen-containing species bound to the crystalline framework. As active sites of the new materials both, terminal -NH 2 and bridging -NH-groups can principally be envisaged. A decrease in catalytic activity is observed upon extended exposure to moisture due to the hydrolysis of the Si-NH 2 groups. The initial catalytic activity, however, can easily be restored by a new ammonia treatment.