Hierarchical Y and USY Zeolites Designed by Post‐Synthetic Strategies
Hierarchical Y and USY Zeolites Designed by Post‐Synthetic Strategies
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DOI：
10.1002/adfm.201102411
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发表时间：
2012-03
影响因子：
19
通讯作者：
D. Verboekend;G. Vilé;J. Pérez–Ramírez
中科院分区：
文献类型：
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作者：
D. Verboekend;G. Vilé;J. Pérez–Ramírez
经济实惠和可扩展的合成后改性的战略组合使得能够设计出广泛的不依赖于Si/Al比的分级Y和USY沸石（FAU拓扑结构）家族。将原始（Y，Si/Al = 2.4）、经蒸汽处理（USY，Si/Al = 2.6）以及经蒸汽处理和脱铝（USY，Si/Al = 15和30）的沸石暴露于各种酸（H4 EDTA和Na 2 H2 EDTA）和碱（NaOH）处理，这导致引入高达500 m2 g-1的中孔表面，同时保持固有的沸石性质。原始Y和USY沸石（Si/Al> 2.5）需要温和的脱铝（在Y的情况下至Si/Al > 4）以促进随后的有效脱硅。具有低Si/Al比（0.4 -6）的Y和USY沸石的碱处理导致丰富的富Al碎片，其可以通过随后的温和酸洗除去。另一方面，严重蒸汽处理和脱铝，因此富含Si的USY沸石（Si/Al = 15和30）被证明对碱性溶液极其敏感，显示出容易溶解和显著的非晶化。对于后一组超稳定Y沸石，TPA+在碱性溶液中的存在使得能够在通过脱硅引入中孔性时保护沸石结构，保持结晶度和结晶体积。分级Y和USY分子筛的吸附和催化性能优于常规的对应物的上级。
Strategic combinations of affordable and scalable post‐synthetic modifications enabled to design a broad family of hierarchical Y and USY zeolites (FAU topology) independent on the Si/Al ratio. Pristine (Y, Si/Al = 2.4), steamed (USY, Si/Al = 2.6), and steamed and dealuminated (USY, Si/Al = 15 and 30) zeolites were exposed to a variety of acid (H4EDTA and Na2H2EDTA) and base (NaOH) treatments, which led to the introduction of mesopore surfaces up to 500 m2 g−1, while preserving the intrinsic zeolite properties. Pristine Y and USY zeolites (Si/Al ∼ 2.5) required mild dealumination (to Si/Al > 4 in the case of Y) to facilitate subsequent efficient desilication. Alkaline treatment of Y and USY zeolites with low Si/Al ratios (∼4–6) led to an abundance of Al‐rich debris, which could be removed by a subsequent mild acid wash. On the other hand, severely steamed and dealuminated, hence Si‐rich, USY zeolites (Si/Al = 15 and 30) proved extremely sensitive to the alkaline solution, displaying facile dissolution and substantial amorphization. For the latter group of ultra‐stable Y zeolites, the presence of TPA+ in the alkaline solution enables to protect the zeolite structures upon the introduction of mesoporosity by desilication, preserving crystallinity and micropore volume. The sorption and catalytic properties of the hierarchical Y and USY zeolites were superior compared to the conventional counterparts.