SSZ-70 borosilicate delamination without sonication: effect of framework topology on olefin epoxidation catalysis.
SSZ-70 borosilicate delamination without sonication: effect of framework topology on olefin epoxidation catalysis.
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DOI：
10.1039/c8dt03044h
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发表时间：
2018-10
影响因子：
4
通讯作者：
A. Okrut;M. Aigner;Christian Schöttle;Nicolás A. Grosso‐Giordano;Son-Jong Hwang;X. Ouyang;S. Zones;Alexander Katz
中科院分区：
文献类型：
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作者：
A. Okrut;M. Aigner;Christian Schöttle;Nicolás A. Grosso‐Giordano;Son-Jong Hwang;X. Ouyang;S. Zones;Alexander Katz
我们报道了一种SSZ-70骨架层状沸石前驱体的可扩展分层过程，这是第一次不涉及超声作用或长链表面活性剂。相反，我们的方法依赖于层状沸石前驱体B-SSZ-70(P)在含锌(NO3)2和四丁基氟化铵的水溶液中的温和加热。粉末X射线衍射数据与沿z方向的长程有序损失相一致，而29Si MAS核磁共振谱表明，在分层过程中沸石骨架的结晶度保持不变。根据77K下的氮气物理吸附数据，得到的分层材料DZ-2的外表面积是未分层的三维分子筛B-SSZ-70的1.4倍。DZ-2被阳离子钛杂原子官能化，通过与骨架B交换合成了钛-DZ-2。以层状分子筛前驱体ERB-1(P)为原料，合成了具有MWW骨架拓扑结构的分层材料DZ-3，说明了合成分层方法和催化剂合成的共性。对以乙苯过氧化氢为氧化剂的1-辛烯环氧化反应的催化性能进行了测试，结果表明，在苛刻的尾部条件使非晶态钛硅基催化剂失活的情况下，在所考察的所有催化剂中，Ti-DZ-2对1-辛烯环氧化表现出最高的每钛位活性、选择性和稳定性。这项测试包括这一领域现有的基准分层沸石催化剂Ti-UCB-4，它的外比表面积与Ti-DZ-2相似，但合成它需要超声波和长链表面活性剂。DZ-2的合成是层状沸石前驱体SSZ-70(P)经济分层的第一个例子，并为分层沸石作为工业催化剂的开发打开了新的大门。
We report a scalable delamination procedure for a SSZ-70-framework layered-zeolite precursor, which for the first time does not involve either sonication or long-chain surfactants. Our approach instead relies on the mild heating of layered zeolite precursor B-SSZ-70(P) in an aqueous solution containing Zn(NO3)2 and tetrabutylammonium fluoride. Powder X-ray diffraction data are consistent with a loss of long-range order along the z-direction, while 29Si MAS NMR spectroscopy demonstrates preservation of the zeolite framework crystallinity during delamination. The resulting delaminated material, DZ-2, possesses 1.4-fold higher external surface area relative to the nondelaminated three-dimensional zeolite B-SSZ-70, based on N2 physisorption data at 77 K. DZ-2 was functionalized with cationic Ti heteroatoms to synthesize Ti-DZ-2 via exchange with framework B. Ti-DZ-2 contains isolated titanium centers in its crystalline framework, as shown by UV-Vis spectroscopy. The generality of the synthetic delamination approach and catalyst synthesis is demonstrated with the synthesis of delaminated material DZ-3, which is derived from layered zeolite precursor ERB-1(P) with MWW framework topology. Upon catalytic testing for the epoxidation of 1-octene with ethylbenzene hydroperoxide as oxidant, under harsh tail-end conditions that deactivate amorphous Ti-silica-based catalysts, Ti-DZ-2 exhibits the highest per-Ti-site activity, selectivity, and stability for 1-octene epoxidation of all catalysts investigated. This testing includes the prior benchmark delaminated zeolite catalyst in this area, Ti-UCB-4, which possesses similar external surface area to Ti-DZ-2 but requires sonication and long-chain surfactants for its synthesis. The synthesis of DZ-2 is the first example of an economical delamination of layered zeolite precursor SSZ-70(P) and opens up new doors to the development of delaminated zeolites as commercial catalysts.