ZSM-5、ZSM-57分子筛和丝光沸石间的转晶规律

Crystal Transformation among ZSM-5,ZSM-57 and Mordenite

考察了硅铝比、碱度、有机胺模板剂、晶化时间及温度等合成条件对ZSM-5、ZSM-57分子筛和丝光沸石之间相互转晶的影响.发现较高的碱度、较长的晶化时间有利于合成丝光沸石;较低的碱度、较高的诱导晶化温度、较长的晶化时间有利于合成低硅铝比的ZSM-57分子筛;合成低硅铝比的ZSM-5分子筛则需要在能合成丝光沸石和ZSM-57分子筛的碱度区间内精确调节碱度,缩短晶化时间、降低诱导晶化温度、加入适当晶种,有利于合成低硅铝比的ZSM-5分子筛.合成条件稍微改变,会导致各种沸石之间发生转晶,晶化产物出现两种或两种以上的晶型.

The crystal transformation among ZSM-5, ZSM-57, and mordenite was studied under different conditions, such as SiO2/Al2O3 molar ratio, alkalinity, n-butylamine template, crystallization time, and temperature. The results showed that higher alkalinity and longer crystallization time were of benefit to mordenite; lower alkalinity and higher induction temperature of crystallization were in favor of ZSM-57 with low n（SiO2）/n（Al2O3） ratio; alkalinity was required to be adjusted accurately to synthesize ZSM-5 with low n（SiO2）/n（Al2O3） ratio, shortening of crystallization time, decrease in induction temperature of crystallization, and the addition of seed crystal were all in favor of ZSM-5 with low n（SiO2）/n（Al2O3） ratio. A slight change in the above conditions would result in the transformation among the three crystals, and two or more crystal phases could be observed in the products.