Acid Treatment for Regulating Hf Sites of the Hierarchical Hf-B-BEA Zeolite, Thereby Boosting Its MPV Reaction Performance
Acid Treatment for Regulating Hf Sites of the Hierarchical Hf-B-BEA Zeolite, Thereby Boosting Its MPV Reaction Performance
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DOI：
10.1021/acs.iecr.3c01104
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发表时间：
2023-06
期刊：
影响因子：
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通讯作者：
Ziqi Ren;Lu Fang;Miao Cui;T. Lv;Huifang Wu;Ziyi Feng;Zhaochi Feng;C. Meng;Limin Ren
中科院分区：
文献类型：
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作者：
Ziqi Ren;Lu Fang;Miao Cui;T. Lv;Huifang Wu;Ziyi Feng;Zhaochi Feng;C. Meng;Limin Ren
催化剂工程在弥合Lewis酸中心结构与其相应催化性能之间的差距方面起着关键作用。在这方面，在调整含HF沸石的活性中心方面所做的工作还远远没有完成，这些沸石对各种氢变换反应具有良好的催化活性。在本论文中，采用水热半重构方法快速制备了HF-B-BEA催化剂，包括母体B-BEA的部分骨架刻蚀和重新组装过程中的HF接枝。然后，进行酸处理以将硼原子从骨架中驱逐出去；更重要的是，引发了HF向硅醇巢的迁移。酸处理有力地推动了半骨架HF向定义良好的四配位骨架HF的转化，从而赋予了所得HF-BEA的Lewis酸性。因此，这一操作大大提高了HF-BEA的Meerwein-Ponndorf-Verley还原性能，而HF-BEA的还原性能几乎比原始的HF-B-BEA无效。Hf位的合理调控为含Hf沸石的设计和构效关系的理解提供了新的思路。
Catalyst engineering plays a key role in bridging gaps between the structure of the Lewis acid center and its corresponding catalytic performance. In this regard, work that has been done in tuning active sites of Hf-containing zeolites, which hold promising catalytic activity for a variety of hydrogen-shift reactions, is far from complete. Herein, a Hf-B-BEA catalyst was rapidly prepared (within hours) by a hydrothermal semi-reconstruction strategy, involving partial framework etching of parent B-BEA and Hf grafting during the reassembling process. Then, an acid treatment was performed for expelling the boron atoms from the framework; more importantly, Hf migration into the silanol nests was triggered. The acid treatment worked powerfully as the driving force for transforming the semi-framework Hf into well-defined tetrahedrally coordinated framework Hf, thus endowing Lewis acidity of the obtained Hf-BEA. Consequently, this operation greatly boosted the Meerwein–Ponndorf–Verley reduction performance of Hf-BEA, which was almost inactive over the pristine Hf-B-BEA. The rational regulation of Hf sites provides new concepts in designing Hf-containing zeolites and understanding the structural–activity relationship.