摘要
以TPAOH为模板剂合成的ZSM-5外表面富Al且内部有大量的缺陷,通过简单的NaOH处理造介孔得到空腔结构,这主要是由于内部的Si更容易脱除,然而这样的孔道结构不利于积碳前驱体的扩散,对于催化剂的稳定性影响很小。1,2而经过一步NH_4F处理之后可以脱除内部缺陷,同时还可以修饰表面的Al,使其对于脱Si没有保护作用,3这样碱处理就可以得到连续孔。不同浓度NH_4F处理之后再进行碱处理可以得到不同的多级孔ZSM-5,这些结构对于甲醇转化反应中积碳前驱体的扩散的影响也有所不同,反应性能差别也比较大。
ZSM-5 templated by TPAOH usually has a silica-rich and defective interior,thus a simple desilication leads to hollow structure because of selectively removing of internal silica.While core-shell ZSM-5 with preserved outer surface seldom facilitates the diffusion of coke precursor and contributes less to longer lifetime.A preliminary fluorination not only removed the internal defective sites but also modified external aluminum which loses protection of outer silica,following desilication generated various hierarchical structure.
引文
[1]M.Milina,S.Mitchell,P.Crivelli,D.Cooke and J.Pérez-Ramírez,Nat.Commun.,2014.
[2]J.C.Groen,J.Pérez-Ramírez,J.Am.Chem.Soc.,2005,127,10792-10793.
[3]L.Yu,S.Huang,S.Miao,F.Chen,S.Zhang,Z.Liu,S.Xie and L.Xu,Chem.Eur.J.,2015,21,1048-1054.