不同双模板剂对ZSM-5分子筛催化剂形貌的影响

Morphological effects of different double templates on ZSM-5 molecular sieve catalysts

固定硅源、铝源和水用量,采用复合模板剂,其中一种模板剂为四丙基氢氧化铵,另一种模板剂为有机胺(乙二胺、1,6-己二胺、异丙胺或三乙胺),通过改变第二种模板剂用量和类型,制备系列ZSM-5分子筛催化剂。采用XRD和SEM进行表征,考察不同双模板剂对ZSM-5分子筛催化剂晶体结构和形貌的影响。结果表明,不同双模板剂合成的产物均为纯相ZSM-5分子筛,且具有较高的结晶度,晶粒外形保持不变,但晶粒尺寸有很大差异,顺序为:四丙基氢氧化铵+三乙胺>四丙基氢氧化铵+异丙胺>四丙基氢氧化铵+1,6-己二胺>四丙基氢氧化铵+乙二胺,可见,只改变模板剂种类而不改变硅源、铝源和水的用量,即可合成相对结晶度高、外形相同但晶粒尺寸不同的ZSM-5分子筛催化剂。

A series of ZSM -5 molecular sieve catalysts were synthesized by fixing the dosage of silicon, aluminum and water, and using double templates, i. e. , tetrapropylammonium hydroxide （TPAOH） and organic amine （ ethylenediamine, 1,6 - hexanediamine, isopropylamine or triethylamine）, changing the sort and dosage of organic amines. The effects of different double templates on crystal structure and morphology （size and shape） of the as - synthesized ZSM - 5 molecular sieve catalysts were studied by means of X -ray powder diffraction and scanning electron microscopy. The results showed that ZSM -5 molecular sieve catalysts synthesized by different double templates were pure -state ZSM -5 molecular sieves with high crystallinity, the same grain shape but much different grain size. The order of grain size vs. templates was as follows ： TPAOH ＋ triethylamine 〉 TPAOH ＋ isopropylamine 〉 TPAOH ＋ 1,6 - hexanediamine 〉 TPAOH ＋ ethylenediamine. It is concluded that ZSM - 5 molecular sieve catalysts of high crystallinity, the same grain shape but different grain size could be synthesized by varying types of double templates while fixing the quantity of silicon, aluminum and water.