晶化时间对CoAPO-11分子筛合成过程中转晶的影响

Effect of crystallization time on crystal transformation during synthesis of CoAPO-11 molecular sieve

本文研究了晶化时间对低钴含量(x=0.1)的CoAPO-11分子筛合成过程中转晶现象的影响,并采用XRD、SEM对产物进行表征。结果表明,200℃下晶化48 h,可获得纯相CoAPO-11;当晶化时间超过48 h时,产物便开始向[Co-Al-P-O]-GIS型分子筛转化;晶化延长至72 h时,产物已全部转化为[Co-Al-P-O]-GIS型分子筛,该转化过程不可逆。从分子筛骨架结构单元出发,阐述了转晶现象的内在影响因素。

The effect of crystallization time on crystal transforulation during synthesis of CoAPO - 11 molecular sieve which contains very low Co content （ x = 0. 1 ） has been investigated. The structures of these samples were characterized by powder X - ray diffraction （ XRD ） and scanning electronic microscopy （ SEM ）. Results revealed that pure CoAPO - 11 could be obtained after mixture were crystallized 24 h at 200 ℃ ,then would gradually transform to[ Co - Al - P - O] - GIS as the crystallization time were extended. And finally the product was pure [ Co- Al- P -O ] -GIS when time was beyond 72 h. It was a irreversible process. The factors related to the transformation phenomenon were illustrated from consideration of the units of framework.