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Selective catalytic reduction of NOx with ammonia (NH3-SCR) over copper loaded LEV type zeolites synthesized with different templates
Physical Chemistry Chemical Physics ( IF 2.9 ) Pub Date : 2022-06-13 , DOI: 10.1039/d2cp01512a
Andreas Hoffmann 1 , Michiel De Prins 1 , Sreeprasanth Pulinthanathu Sree 1 , Gina Vanbutsele 1 , Sam Smet 1 , C Vinod Chandran 1 , Sambhu Radhakrishnan 1 , Eric Breynaert 1 , Johan A Martens 1
Affiliation  

LEV type zeolites were synthesized with four different structure-directing agents and converted to copper loaded NH3-SCR catalysts. The synthesis recipe was found to impact the respective Al population in the two topologically different framework sites in double and single 6-rings, resolvable by 27Al MAS NMR spectroscopy. Hydrothermal stability was found to be related to the silanol concentration, Si/Al ratio, particle size, crystal morphology, crystal defects, external surface area, and microporosity. Catalytic activity in NH3-SCR was dependent on preferential Al siting in the double 6-rings. Levinite synthesized using adamantylamine showed the strongest preference for Al atoms sitting in double 6-ring sites, and showed the highest catalytic turnover frequency. Unfortunately, because of the large crystal size, copper loading of this sample was limited to 0.6 wt% while other samples could be loaded with copper up to 3.3 wt%. An optimum combination of hydrothermal stability and catalytic activity was obtained with N,N′-bis-dimethylpentanediyldiammonium dibromide as structure-directing agent.

中文翻译:

不同模板合成的载铜LEV型沸石氨选择性催化还原NOx(NH3-SCR)

LEV 型沸石用四种不同的结构导向剂合成,并转化为载铜的 NH 3 -SCR 催化剂。发现合成配方会影响双 6 环和单 6 环中两个拓扑不同的框架位点中的各自 Al 群体,可通过27 Al MAS NMR 光谱解析。发现水热稳定性与硅醇浓度、Si/Al比、粒度、晶体形态、晶体缺陷、外表面积和微孔率有关。NH 3中的催化活性-SCR 依赖于双 6 环中的优先 Al 位点。使用金刚胺合成的 Levinite 对位于双 6 环位点的 Al 原子表现出最强的偏好,并表现出最高的催化周转频率。不幸的是,由于晶体尺寸大,该样品的铜负载量限制在 0.6 wt%,而其他样品的铜负载量最高可达 3.3 wt%。以N , N'-双-二甲基戊二基二溴化二铵作为结构导向剂获得了水热稳定性和催化活性的最佳组合。
更新日期:2022-06-16
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