The tailoring of hierarchical structures in beta zeolites of differing Al contents (Si/Al: 14-250) has been systematically investigated through a top-down base leaching process with various cationic tetraalkylammonium (TAA) salts and organic amines as pore-directing agents (PDAs) to examine their effectiveness in protecting beta zeolite framework while directing the formation of mesopores. The structure-property relationship was established between PDA structure and average mesopore sizes in resulting hierarchical zeolites, especially for high Si beta zeolites when the presence of PDA is necessary to avoid framework amorphization during NaOH desilication. All PDAs studied are effective in directing the mesopore formation in alkaline solutions without experiencing significant decrease in microporosity and crystallinity of parent beta zeolites. For high Si beta zeolites, hierarchical structures with non-ionic amines possess larger mesopores (average mesopore sizes, d_a: 5-8 nm) than those treated with TAA cationic PDAs (d_a: 2-6 nm), which should be due to better accommodation of TAA-type cationic PDAs within the inner channel of beta framework and more favorable interaction and protection of parent framework as compared to organic amines. For similarly structured TAA cations, the resulting mesopore sizes and surface areas are correlated with the molecular weights of different cations, i.e. higher molecular weight cations result in smaller d_a and correspondingly larger surface areas. Therefore, it is feasible to tailor the mesopore sizes by a top-down base leaching with an appropriate selection of PDAs for beta zeolites. The successful introduction of mesopores in beta zeolites also led to significantly improved catalytic conversion for the acid-catalyzed alpha-pinene isomerization, as compared to the parent beta catalysts.

已通过自上而下的碱浸过程以各种阳离子四烷基铵（TAA）盐和有机胺作为孔导向剂，系统研究了Al含量不同的β沸石（Si / Al：14-250）中的层级结构（ PDA）来检查其在保护β沸石骨架中的有效性，同时指导中孔的形成。在所得分层沸石中，特别是对于高Siβ沸石，当需要存在PDA以避免NaOH脱硅过程中骨架无定形时，在PDA结构与平均中孔尺寸之间建立了结构-性质关系。所有研究的PDA均可有效地引导碱性溶液中的中孔形成，而母体β沸石的微孔率和结晶度却没有显着降低。d _a：5-8 nm）比用TAA阳离子PDA（d _a：2-6 nm）处理的那些（d _a：2-6 nm），这应归因于TAA型阳离子PDA在β骨架的内部通道内具有更好的适应性，并且相互作用和与有机胺相比，保护母体骨架。对于结构相似的TAA阳离子，所得的中孔尺寸和表面积与不同阳离子的分子量相关，即，较高分子量的阳离子可导致d _a较小。以及相应更大的表面积。因此，通过自上而下的碱浸并为β沸石选择适当的PDA来调整介孔尺寸是可行的。与母体β催化剂相比，中孔在β沸石中的成功引入还显着提高了酸催化的α-pine烯异构化的催化转化率。