Catalyst Site Requirements for Olefin Etherification over H-Beta Zeolites

作者：Wen-Sheng Lee, Paulami Majumdar, Kimberly T. Dinh, Swati Naik, Binghe Gu, Joo Kang, Xiaohua Qiu, Siaka Yusuf, Denise Anaya, John Klann, Wang‐Lin Yu, Thomas Peterson, David G. Barton, Rachel E. M. Brooner · 发表于：ACS Catalysis · 年份：2024 · DOI：10.1021/acscatal.4c03487 · 被引用次数：8 · 研究领域：Zeolite Catalysis and Synthesis、Catalysis and Hydrodesulfurization Studies、Asymmetric Hydrogenation and Catalysis

We report site requirements for H-Beta zeolites for the etherification of hydrophobic long-chain olefins with hydrophilic alcohols in a triphasic system using 1-dodecene and ethylene glycol as model reactants. Olefin etherification rates normalized by total Al monotonically increased as the Si/Al molar ratio increased up to 75 (Al content decreased), suggesting that a large portion of Al does not contribute to etherification activity for H-Beta zeolites with a low Si/Al ratio. The olefin consumption rate per Al correlated well with the surface hydrophobicity of the H-Beta zeolites. Thus, we hypothesized that the impact of Si/Al on long-chain olefin etherification activity for H-Beta zeolites under these reaction conditions was caused by the increasing hydrophobicity of the zeolites with decreasing Al content (increasing the Si/Al ratio). We found that when titrating an H-Beta zeolite with basic molecules that could enter the zeolite’s micropores (0.77 × 0.66 and 0.56 × 0.56 nm), no etherification activity was observed, indicating that long-chain olefin etherification occurs inside the microporous channels. From titrating with 2,6-di tert -butyl-pyridine, we inferred that Lewis acidic Al sites within the micropores of H-Beta have little contribution to long-chain olefin etherification because 2,6-di tert -butyl-pyridine can enter the micropores of H-Beta and bind only to Brønsted acid sites. In summary, we demonstrate that Brønsted acid sites inside the micropores of H-Beta wi...