晶种导向下干胶法合成ZSM-5分子筛

Organic-Free and Seeded-Directed Synthesis of ZSM-5 Zeolite by Dry-Gel Conversion Method

以廉价水玻璃为硅源,在晶种替代有机模板剂的条件下采用干胶法合成了ZSM-5分子筛。利用XRD、SEM、TEM、FTIR、N_2吸附-脱附和NH_3-TPD等分析方法对合成样品进行了表征和测试,考察了合成条件对ZSM-5分子筛晶化过程的影响。结果表明,在硅铝比(n/n)为30~70,钠硅比(n/n)为0.12~0.20时都可以得到结晶度良好的ZSM-5分子筛。研究发现,干胶法合成ZSM-5,在不引入外加水的情况下也可以得到ZSM-5样品,外加水的引入能够有效地提高晶化速率;与水热法合成ZSM-5分子筛相比,干胶法可以显著地缩短晶化时间,同时,合成样品的晶体尺寸也有所减小。

The synthesis of ZSM-5 zeolite by seeded dry-gel conversion method using water glass as a cheap silica source was studied. The products were characterized using XRD, SEM, TEM, FTIR, N2 adsorption- desorption and NH3-TPD. The crystallization process of ZSM-5 zeolite was investigated in detail. The results show that ZSM-5 zeolite can be synthesized when the ratio of nsio2/nAl2O3 is 30-70, nNa^o/nsio2 is 0.12-0.2, even in the absence of external bulk water. The added of external bulk water can accelerate the crystallization speed. Compared with the products synthesized by conventional hydrothermal synthesis method, the dry-gel synthesized ZSM-5 zeolite show much smaller cry-stal size and much shorter crystallization time.