This study examines how the inherent diffusion constraints of MFI (3D, pore-limiting diameter (PLD) = 0.45 nm), BEA (3D, PLD = 0.60 nm), and MOR (1D, PLD = 0.65 nm) zeolite architectures, at both nanocrystal (nMFI, nBEA, nMOR; d_crystal < 0.5 μm) and microcrystal (μBEA, μMOR; d_crystal > 0.5 μm) scales, impact functions of mesopores in their hierarchical analogs. Reactivities, deactivation rates, and product selectivities were compared among zeolites, as well as to a mesoporous aluminosilicate control (Al-MCM-41; PLD = 6.2 nm), during Friedel–Crafts alkylation of 1,3,5-trimethylbenzene (TMB; d_vdW = 0.72 nm) with benzyl alcohol (BA; d_vdW = 0.58 nm) to form 1,3,5-trimethyl-2-benzylbenzene (TM2B; d_vdW = 0.75 nm). Operation in the neat liquid phase ([TMB]₀ : [BA]₀ = 35 : 1, 393 K) ensured that the parallel BA self-etherification to yield dibenzyl ether (DBE; d_vdW = 0.58 nm) occurred only at the expense of TM2B production when the alkylation reaction was impeded due to hindered access of TMB to confined protons. Investigation of secondary TM2B formation from reaction of DBE with TMB at low [BA]/[DBE] indicates an additional route of selectivity control for hierarchical zeolites that can achieve high BA conversion (X_BA > 0.9) with no DBE cofeed. These findings highlight a compounding advantage of increased diffusivity in mesopores that alter rates, extend lifetimes, and subsequently permit secondary reactions that enable significant shifts in product distribution. Fundamental insights into hierarchical zeolite reaction–diffusion–deactivation for alkylation of poly-substituted aromatics, as detailed here, can be applied broadly to reactions of other bulky species, including biomass-derived oxygenates, for more atom-efficient chemical and fuel production.

中文翻译：

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多取代芳烃的烷基化以探测具有不同骨架和晶体尺寸的分级沸石中介孔的影响

本研究探讨了 MFI（3D，孔隙限制直径 (PLD) = 0.45 nm）、BEA（3D，PLD = 0.60 nm）和 MOR（1D，PLD = 0.65 nm）沸石结构的固有扩散约束，在这两种情况下纳米晶体（nMFI、nBEA、nMOR；d_晶体< 0.5 μm）和微晶体（μBEA、μMOR；d_晶体> 0.5 μm）尺度，介孔在其分级类似物中的影响功能。在 1,3,5-三甲苯 (TMB;) 的 Friedel-Crafts 烷基化过程中，比较了沸石以及介孔硅铝酸盐对照（Al-MCM-41；PLD = 6.2 nm）的反应活性、失活率和产物选择性。d _vdW = 0.72 nm) 与苯甲醇 (BA; d _vdW= 0.58 nm) 形成 1,3,5-三甲基-2-苄基苯 (TM2B; d _vdW = 0.75 nm)。在纯液相 ([TMB] ₀  : [BA] ₀ = 35 : 1, 393 K) 中操作确保平行 BA 自醚化以产生二苄基醚 (DBE; d _vdW = 0.58 nm) 仅以牺牲为代价发生当由于 TMB 无法进入受限质子而阻碍烷基化反应时，TM2B 产生的影响。对 DBE 与 TMB 在低 [BA]/[DBE] 下反应形成的二次 TM2B 的研究表明，可以实现高 BA 转化率的分级沸石选择性控制的额外途径（X _BA> 0.9) 没有 DBE 共进料。这些发现强调了增加中孔扩散率的复合优势，可以改变速率、延长寿命，并随后允许二次反应，从而使产品分布发生显着变化。对多取代芳烃烷基化的分级沸石反应-扩散-失活的基本见解，如本文所详述，可广泛应用于其他大物质的反应，包括生物质衍生的含氧化合物，以提高原子效率的化学和燃料生产。