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Synthesis and activation for catalysis of Fe-SAPO-34 prepared using iron polyamine complexes as structure directing agents

DOI: 10.1039/C7CY01269A DOI Help

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)