Synthesis and activation for catalysis of Fe-SAPO-34 prepared using iron polyamine complexes as structure directing agents
Abstract
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 Mössbauer, 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.
Citation
Turrina , A , Dugulan , A I , Collier , J , Walton , R I , Casci , J L & Wright , P 2017 , ' Synthesis and activation for catalysis of Fe-SAPO-34 prepared using iron polyamine complexes as structure directing agents ' , Catalysis Science & Technology , vol. 7 , no. 19 , pp. 4366-4374 . https://doi.org/10.1039/C7CY01269A
Publication
Catalysis Science & Technology
Status
Peer reviewed
ISSN
2044-4753Type
Journal article
Description
This work was supported by Johnson Matthey PLC, UK. Solid-state NMR spectra were obtained at the EPSRC UK National Solid-state NMR Service at Durham.Collections
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