Synthesis of ZSM-5 from Low Modulus Sodium Metasilicate System and Optimization of Process Conditions
SUN Hao, WANG Bao-He
(R & D Center for Petrochemical Technology, Key Laboratory for Green Chemical Technology of State Education Ministry, Tianjin University, Tianjin 300072, China)
Abstract：
Template-Free ZSM-5 from low modulus (n=1.03) sodium metasilicate synthesis mixture were successfully synthesized through an improvement hydrothermal synthesis route. The crystallinities and morphologies of the ZSM-5 zeolites were characterized with X-ray diffraction (XRD) and scanning electron microscopy (SEM). In the case of silica alumina ratio of 50, the synthesis process was optimized by examining the effect of crystallization temperature, time, pH, water content, stir and seed crystal on the properties of ZSM-5 zeolites. ZSM-5 zeolites with big crystal size, irregular morphology were obtained from static or crystal seed method，the results showed that those two methods were not suitable for synthesis of ZSM-5 system. The suitable synthesis conditions of ZSM-5 zeolite are as follows: pH=10, n(H2O)/n(SiO2)=40, aged at room temperature for 24 h, hydrothermal crystallization at 170 ℃ for 24 h. Compared with the commercial ZSM-5, ZSM-5 zeolites obtained from low modulus sodium metasilicate synthesis mixture exhibited a higher catalytic activity and selectivity in the hydration reaction of cyclohexene.
SUN Hao, WANG Bao-He.Synthesis of ZSM-5 from Low Modulus Sodium Metasilicate System and Optimization of Process Conditions[J]. Chemcial Industry and Engineering, 2014,31(5): 37-42
2014, Vol. 31 
