Synthesis and activation for catalysis of Fe-SAPO-34 prepared using iron polyamine complexes as structure directing agents
Synthesis and activation for catalysis of Fe-SAPO-34 prepared using iron polyamine complexes as structure directing agents
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DOI：
10.1039/c7cy01269a
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发表时间：
2017-10
影响因子：
5
通讯作者：
Alessandro Turrina;A. Dugulan;J. Collier;R. Walton;J. Casci;P. Wright
中科院分区：
文献类型：
--
作者：
Alessandro Turrina;A. Dugulan;J. Collier;R. Walton;J. Casci;P. Wright
使用与多胺络合的过渡金属阳离子作为硅铝磷酸盐（SAPO）沸石型的结构导向剂（SDA）提供了一种途径，通过煅烧除去有机物，得到具有均匀分布的催化活性骨架外阳离子的微孔固体，并避免了合成后含水阳离子交换的需要。发现与四亚乙基五胺（TEPA）络合的铁（II）是SAPO-34的有效SDA，得到制备的固体，其中Fe 2 +-TEPA络合物驻留在cha笼内，如穆斯堡尔、光学和X射线吸收近边光谱所示。相比之下，当非配位四乙基铵离子用作Fe-SAPO-34制备中的SDA时，铁作为八面体Fe 3+包含在骨架内。当在空气中干燥时，含络合物的Fe-SAPO-34（TEPA）材料在550 nm处产生特征可见吸收带（和紫色），这归因于氧化学吸附。一些其他的Fe 2+多胺络合物（二亚乙基三胺，三亚乙基四胺和五亚乙基六胺）表现出类似的行为。在550 °C下在流动氧气中煅烧后，“一锅法”Fe（TEPA）材料具有Fe 3+阳离子和特征UV-可见光谱：它们在用NH3选择性催化还原NO中也显示出可观的活性。
The use of transition metal cations complexed by polyamines as structure directing agents (SDAs) for silicoaluminophosphate (SAPO) zeotypes provides a route, via removal of the organic by calcination, to microporous solids with well-distributed, catalytically-active extra-framework cations and avoids the need for post-synthesis aqueous cation exchange. Iron(II) complexed with tetraethylenepentamine (TEPA) is found to be an effective SDA for SAPO-34, giving as-prepared solids where Fe2+–TEPA complexes reside within the cha cages, as indicated by Mossbauer, optical and X-ray absorption near edge spectroscopies. By contrast, when non-coordinating tetraethylammonium ions are used as the SDAs in Fe-SAPO-34 preparations, iron is included as octahedral Fe3+ within the framework. The complex-containing Fe-SAPO-34(TEPA) materials give a characteristic visible absorption band at 550 nm (and purple colouration) when dried in air that is attributed to oxygen chemisorption. Some other Fe2+ polyamine complexes (diethylenetriamine, triethylenetetramine and pentaethylenehexamine) show similar behaviour. After calcination in flowing oxygen at 550 °C, ‘one-pot’ Fe(TEPA) materials possess Fe3+ cations and a characteristic UV-visible spectrum: they also show appreciable activity in the selective catalytic reduction of NO with NH3.