The Alkylation of Naphthalene over One-Dimensional Fourteen-Membered Ring Zeolites. The Influence of Zeolite Structure and Alkylating Agent on the Selectivity for Dialkylnaphthalenes
作者：Yoshihiro Sugi、Hiroyoshi Maekawa、Hiroaki Naiki、Kenichi Komura、Yoshihiro Kubota
DOI：10.1246/bcsj.81.1166
日期：2008.9.15
The alkylation, i.e., isopropylation, s-butylation, and t-butylation, of naphthalene (NP) was examined over one-dimensional fourteen-membered (14-MR) zeolites: CIT-5 (CFI), UTD-1 (DON), and SSZ-53 (SFH), and compared to the results over H-mordenite (MOR) to elucidate how zeolite structure and alkylating agent play roles in the shape-selective catalysis. The β,β-selectivities (for β,β-dialkylnaphthalene (2,6- and 2,7-dialkylnaphthalenes, β,β-DAN)) and the 2,6-selectivities (for 2,6-DAN) were varied with the types of zeolite and of alkylating agent. MOR gave high β,β-selectivities in the all alkylations in the range of 150–300 °C. However, the 14-MR zeolites, CFI, DON, and SFH, gave much lower β,β-selectivities in the isopropylation: bulky and less stable α,β- and α,α-diisopropylnaphthalenes (α,β-DIPN: 1,3-, 1,5-, and 1,7-DIPN); α,α-DIPN (1,4- and 1,5-DIPN) were predominantly obtained under kinetic control at low temperatures, and stable and less bulky β,β-DIPN were formed under thermodynamic control at high temperatures. The β,β-selectivities were higher than 95% over CFI in the s-butylation, and increased from 50–60% at 150 °C to 75% at 300 °C over DON and SFH, respectively. They were almost 100% in the t-butylation over all zeolites. The alkylation over MOR occurred with high 2,6-selectivities in the range of 150–250 °C: 60% for the isopropylation, 80% for the s-butylation, and 95% for the t-butylation. CFI, DON, and SFH gave the 2,6-selectivities in the range of 5–30% in the isopropylation, 65%, 55%, and 50%, respectively, in the s-butylation, and higher than 80% in the t-butylation. These different features are explained by the discrimination of the least bulky DAN isomers from the other isomers by steric restriction with the zeolite channels at the transition states: β,β-DAN from the DAN isomers, and 2,6-DAN from β,β-DAN. The bulkiness of alkylating agent also enhances the discrimination of the isomers, particularly, between 2,6- and 2,7-DAN. The β,β- and 2,6-selectivities are synergistically governed by the zeolite channel and the bulkiness of alkylating agents.
研究了萘 (NP) 在一维十四元胞（14-MR）沸石上的烷基化，即异丙基化、叔丁基化和叔丁基化：CIT-5（CFI）、UTD-1（DON）和 SSZ-53（SFH），并与 H-莫来石（MOR）上的结果进行了比较，以阐明沸石结构和烷基化剂如何在形状选择催化中发挥作用。β,β-选择性（对 β,β-二烷基萘（2,6- 和 2,7-二烷基萘，β,β-DAN））和 2,6-选择性（对 2,6-DAN）随沸石类型和烷化剂的不同而变化。在 150-300 °C 范围内，MOR 在所有烷基化反应中都具有较高的β,β-选择性。然而，14-MR 沸石、CFI、DON 和 SFH 在异丙基化反应中的 β、β-选择性要低得多：体积大且不太稳定的 α、β- 和 α、α-二异丙基萘（α、β-DIPN：α,β-二异丙基萘（α,β-DIPN：1,3-、1,5- 和 1,7-DIPN）；α,α-二异丙基萘（1,4- 和 1,5-DIPN）主要是在低温下通过动力学控制获得的，而稳定且体积较小的 β,β-二异丙基萘则是在高温下通过热力学控制形成的。在 s 丁基化反应中，相对于 CFI 的 β,β-选择性高于 95%，相对于 DON 和 SFH 的 β,β-选择性分别从 150 ℃ 时的 50-60% 增加到 300 ℃ 时的 75%。在所有沸石上的 t-丁基化过程中，烷基化率几乎达到 100%。在 150-250 °C的范围内，在 MOR 上发生的烷基化具有很高的 2,6-选择性：异丙基化为 60%，s-丁基化为 80%，t-丁基化为 95%。CFI、DON 和 SFH 在异丙基化反应中的 2,6 选择性为 5-30%，在 s-丁基化反应中分别为 65%、55% 和 50%，而在 t-丁基化反应中则高于 80%。这些不同特征的原因是，在过渡状态下，沸石通道的立体限制将体积最小的 DAN 异构体与其他异构体区分开来：β,β-DAN 与 DAN 异构体区分开来，2,6-DAN 与 β,β-DAN 区分开来。烷基化剂的体积也提高了异构体的鉴别能力，特别是 2,6- 和 2,7-DAN 之间的鉴别能力。沸石通道和烷基化剂的体积对 β、β- 和 2,6-选择性具有协同作用。
