Designed Synthesis of STA-30: A Small-Pore Zeolite Catalyst with Topology Type SWY
Designed Synthesis of STA-30: A Small-Pore Zeolite Catalyst with Topology Type SWY
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DOI：
10.1021/acs.chemmater.1c01329
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发表时间：
2021-06-18
影响因子：
8.6
通讯作者：
Wright, Paul A.
中科院分区：
文献类型：
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作者：
Chitac, Ruxandra G.;Bradley, Jonathan;Wright, Paul A.
小孔铝硅酸盐沸石是合成的有吸引力的目标，因为它们在重要反应中作为催化剂的活性，包括汽车尾气排放中NOx的氨介导的选择性催化还原（SCR）。这种具有SWY骨架类型的沸石（先前观察为硅铝磷酸盐）已经通过设计的合成使用有机1，8-（1，4-二氮杂双环[2.2.2]辛烷）辛基（diDABCO-C8）和K+阳离子作为模板剂来制备具有高结晶度。STA-30（St Andrews微孔材料30）是表现出12层堆叠序列AABAABAACAAC的毛沸石-菱钾沸石族沸石中的ABC-6结构。可以用可控的Si/Al比制备的骨架具有交替的d 6 r单元和can笼的柱，其中后者被定向以给出包含经由8 R连接的gme笼和sw y笼的柱间孔隙空间。DiDABCO-C8阳离子填充了所制备的STA-30的swy笼，而K+阳离子在罐笼中显示出高占有率。通过煅烧除去模板剂，然后用铵离子交换罐笼外的K+阳离子，随后脱氨，得到高度结晶的沸石（K3 H6 Al 9 Si 72 O 144，P6（3）/ mmc，a = 12.9922（9）埃，c = 29.9624（12）埃），其固体酸性由固态H-1 MAS NMR显示。在水合时，一部分Al采用八面体几何形状，如Al-27 MAS NMR中在-2.0和-3.1 ppm处的两个尖锐共振所证明的。这些八面体物种可以转换回四面体铝铵交换，并解释为不同的水合框架铝网站。活化的K，H-STA-30是一种小孔固体酸，三维连通的孔体积为0.31 cm（3）g（-1）。在负载铜的形式下，它是用于通过氨的NO的SCR的活性催化剂。
Small-pore aluminosilicate zeolites are attractive targets for synthesis because of their activity as catalysts in important reactions, including ammonia-mediated selective catalytic reduction (SCR) of NOx in auto-exhaust emissions. Such a zeolite with SWY framework type, previously observed as a silicoaluminophosphate, has been prepared with high crystallinity via designed syntheses employing organic 1,8-(1,4-diazabicyclo[2.2.2]octane)octyl (diDABCO-C8) and K+ cations as templates. STA-30 (St Andrews microporous material 30) is an ABC-6 structure in the erionite-offretite family of zeolites that exhibits the 12-layer stacking sequence AABAABAACAAC. The framework, which can be prepared with a controllable Si/Al ratio, possesses columns of alternating d6r units and can cages, of which the latter are oriented to give an inter-column pore space comprising gme cages and swy cages connected via 8Rs. DiDABCO-C8 cations fill the swy cages of as-prepared STA-30, while K+ cations display high occupancy in the can cages. Removal of the template by calcination, followed by ammonium ion exchange of K+ cations residing outside the can cages and subsequent deammoniation, gives a highly crystalline zeolite (K3H6Al9Si72O144, P6(3)/ mmc, a = 12.9922(9) angstrom, c = 29.9624(12) angstrom) with solid acidity shown by solid-state H-1 MAS NMR. Upon hydration, a portion of the Al adopts octahedral geometry, as demonstrated by two sharp resonances at -2.0 and -3.1 ppm in the Al-27 MAS NMR. These octahedral species can be converted back to tetrahedral Al by ammonium exchange and are interpreted as distinct hydrated framework Al sites. The activated K,H-STA-30 is a small-pore solid acid with a three-dimensionally connected micropore volume of 0.31 cm(3) g(-1). In the copper-loaded form, it is an active catalyst for the SCR of NO by ammonia.