Studies on the Non - Spontaneous Crystallization Kinetics of MAP Zeolite

Pure phase of MAP zeolite ( GIS type ) was synthesized in the highly basic solution with water glass and aluminum sulfate as raw material by seeding with NaP, an isotopic silica rich GIS type zeolite. The molar ratios of the reactant composition were Na2O: Al2O3 : SiO2 :H2O =(2.4~5.4):1.0:2.0:102.6. The crystallization of the zeolite was carried out at the temperature of 70℃, 80℃, 90℃ and100℃, respectively. The influence of the ratio of Na2O/SiO2, the reaction temperature, and the reaction time was investigated. A process for transformation zeolite A to zeolite MAP was observed in the reactant with XRD. The crystallinity of the zeolite prepared was high when increasing the synthesis temperature. The crystallization kinetic curves were determined in the reactant with or without seeding at differentreaction temperature. The apparent energy of crystallization activation is 59. 6kJ·mol-1 calqulated from the crystallization curves at different reaction temperature. Pure phase of zeolite A was obtained in the same reactant and at the same reaction conditions without seeding. The activation energy of nucleationand crystallization is 40.3 kJ·mol-1 and 50.7kJ·mol-1 respectively for zeolite A in same reactant system. The high crystallization activation energy for MAP zeolite reveals the reason for seeding while synthesis.