无导向剂水热合成条件对NaY型分子筛结构及形貌的影响

Effects of Synthesis Conditions on the Structure and Morphology of NaY Zeolite by Hydrothermal Method without Seed Gel

以硅酸钠和铝酸钠为主要原料,在无导向剂条件下,采用直接晶化法制备了NaY型分子筛。考察了陈化时间、晶化时间、晶化温度、体系的水含量和n(Na2O)/n(SiO2)等因素对分子筛结构和形貌的影响。分别采用X射线衍射(XRD)和扫描电子显微镜(SEM)对样品进行了表征。结果表明:延长陈化时间有利于生成更多的晶核,但陈化时间过长会导致分子筛粒径增大;晶化温度的升高和晶化时间的延长使分子筛结晶度升高,但产物易出现转晶现象,生成杂晶;n(Na2O)/n(SiO2)和n(H2O)/n(Al2O3)对产物结晶度影响较大,合成高结晶度的NaY型分子筛所需要的合适的n(Na2O)/n(SiO2)和n(H2O)/n(Al2O3)分别为1.0和160。

Using sodium silicate and sodium aluminate as raw materials,NaY zeolites were synthesized by direct crystallization without seed gel.The hydrothermal synthesis conditions including aging time,crystallization temperature and time,water content and n（Na_2O）/n（SiO_2） in the system were investigated in detail.The synthesized zeolites were characterized by X-ray diffraction（XRD） and scanning electron microscopy（SEM）.The results indicate that increasing aging time favors the formation of more nuclears,but too long aging time leads to increase particle size of zeolite.Prolonging crystal temperature and time increases the crystallinity of NaY zeolite,while trans-crystalliziation phenomena occur easily and lead to mixed-crystal.The crystallinity of product is highly affected by n（Na_2O）/n（SiO_2） and n（H_2O）/（n（Al_2O_3）.） High crystallinity NaY zeolites are synthesized when n（Na_2O）/n（SiO_2） and n（H_2O）/n（Al_2O_3） are 1.0 and 160,respectively.