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Synthesis and activation for catalysis of Fe-SAPO-34 prepared using iron polyamine complexes as structure directing agents
Authors:
Alessandro
Turrina
(University of St Andrews; Johnson Matthey Technology Centre)
,
Iulian
Dugulan
(Delft University of Technology)
,
Jillian
Collier
(Johnson Matthey Technology Centre)
,
Richard I.
Walton
(University of Warwick)
,
John L
Casci
(Johnson Matthey Technology Centre)
,
Paul
Wright
(University of St. Andrews)
Co-authored by industrial partner:
Yes
Type:
Journal Paper
Journal:
Catalysis Science & Technology
State:
Published (Approved)
Published:
August 2017
Diamond Proposal Number(s):
9741
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.
Subject Areas:
Chemistry,
Materials
Instruments:
B18-Core EXAFS
Added On:
06/09/2017 16:01
Discipline Tags:
Molecular Complexes
Physical Chemistry
Catalysis
Chemistry
Materials Science
Technical Tags:
Spectroscopy
X-ray Absorption Spectroscopy (XAS)
Extended X-ray Absorption Fine Structure (EXAFS)