Process regulation of microwave intensified synthesis of Y-type zeolite

Abstract

Abstract A rapid microwave heating method is proposed for the liquid phase synthesis of Y-type zeolite under high-temperature conditions. The effect of microwave heating temperatures, crystallization time and silica to alumina ratio on the synthesis of Y-type zeolite is systematically investigated. The synthesized samples are characterized by XRD, SEM, FT-IR, N2 sorption and particle size analysis. Microwave treatment was found to promote the high-temperature synthesis of Y-type zeolite with the advantages of shorter crystallization time and product properties of the produced Y-type zeolite. Specifically, under the optimized conditions, such as input ratio of Si/Al of 4, microwave heating temperature of 150 °C, crystallization time of 0.5 h, pure Y-type zeolite is synthesized with BET specific surface area of 645 m2/g and the total pore volume is 0.322 cm3/g. The evolution order of zeolites with crystallization temperature is as follows: amorphous phase, Y-type zeolite, and P2 zeolite. An extended crystallization time or increased ratio of Si/Al facilitated the formation of P2 zeolite and analcime-C. The synthesis process promoted by microwave is explained by the high-speed rotation of polar water molecules, the formation of isolated water molecules and the dispersion of initial aluminosilicate gel in the microwave field.