Synthesis of hierarchical lamellar MFI zeolites with sequential intergrowth influenced by synthetic gel composition
Synthesis of hierarchical lamellar MFI zeolites with sequential intergrowth influenced by synthetic gel composition
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DOI：
10.1016/j.micromeso.2018.08.007
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发表时间：
2019-02
影响因子：
5.2
通讯作者：
L. Emdadi;Dat T. Tran;Emily Schulman;Lu Wei;Wenjin Shang;Huiyong Chen;Dongxia Liu
中科院分区：
文献类型：
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作者：
L. Emdadi;Dat T. Tran;Emily Schulman;Lu Wei;Wenjin Shang;Huiyong Chen;Dongxia Liu
分级层状沸石由微孔和中孔组成，在大分子加工中提供高活性位点可及性和质量传输。在这里，我们报道了通过 100SiO2/0.5Al2O3/3C22-6-6/18.5Na2O/4000H2O 标准配方中的成分变化诱导的连续共生的分级层状 MFI 沸石的合成，其中 C22-6-6 代表双季铵表面活性剂（[C22H45单键N+(CH3)2单键）键C6H12单键N+(CH3)2单键C6H13]Br−2)模板。研究了C22-6-6浓度、碱度和铝量对分级层状MFI沸石共生的影响。分析了共生对介孔性的影响。在所有研究的合成条件下，除了非常低的碱度外，分级层状 MFI 沸石均成功结晶。合成凝胶中模板浓度的增加导致共生增加，从而导致分级 MFI 产品中的中孔结构增加。碱度的增加导致分级 MFI 产物的中孔率先增加后减少，这反映了水热合成过程中共生的相同趋势。然而，铝浓度并没有显着影响所得分级MFI沸石的共生和中孔率。通过简单改变层状 MFI 沸石的合成组成即可实现顺序共生，从而一步获得更高的结构层次、中孔率和酸位可及性。
Hierarchical lamellar zeolites, comprised of both micro- and mesoporosity, afford high active site accessibility and mass transport in processing of bulky molecules. Here, we report the synthesis of hierarchical lamellar MFI zeolites with sequential intergrowth that is induced by composition variation in the standard recipe of 100SiO2/0.5Al2O3/3C22-6-6/18.5Na2O/4000H2O, where C22-6-6stands for the diquaternary ammonium surfactant ([C22H45single bondN+(CH3)2single bondC6H12single bondN+(CH3)2single bondC6H13]Br−2) template. The influences of C22-6-6concentration, alkalinity, and aluminum amount on the intergrowth of hierarchical lamellar MFI zeolites were investigated. The consequences of intergrowth on mesoporosity were analyzed. In all studied synthesis conditions except for very low alkalinity, hierarchical lamellar MFI zeolites were successfully crystallized. The increasing template concentration in the synthesis gel resulted in an increase in intergrowth and thus mesoporsotiy in the hierarchical MFI products. The increasing alkalinity led to an increase and then a decrease in mesoporosity in the hierarchical MFI products, which reflects the same trend in intergrowth in the hydrothermal synthesis process. The aluminum concentration, however, did not significantly affect the intergrowth and mesoporosity of the resultant hierarchical MFI zeolites. The sequential intergrowth achieved by simple variation in the synthesis composition for lamellar MFI zeolites resulted in higher structure hierarchy, mesoporosity, and acid site accessibility in one-step.