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Understanding the structure directing action of copper–polyamine complexes in the direct synthesis of Cu-SAPO-34 and Cu-SAPO-18 catalysts for the selective catalytic reduction of NO with NH3

DOI: 10.1016/j.micromeso.2015.05.038 DOI Help

Authors: Alessandro Turrina (University of St Andrews) , Eike Christian Eschenroeder (University of St Andrews) , Bela E. Bode (University of St Andrews) , Jillian Collier (Johnson Matthey) , David C. Apperley (Durham University) , Paul A. Cox (University of Portsmouth) , John L. Casci (Johnson Matthey) , Paul Wright (University of St Andrews)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Microporous And Mesoporous Materials , VOL 215 , PAGES 154 - 167

State: Published (Approved)
Published: October 2015
Diamond Proposal Number(s): 8875

Abstract: Cu2+ cations complexed by linear polyamines have been studied as structure-directing agents (SDAs) for the direct synthesis of copper-containing microporous silicoaluminophosphate (SAPO) materials. The complexing ligands diethylenetriamine (DETA), N-(2-hydroxyethyl)ethylenediamine (HEEDA), triethylenetetramine (TETA), N,N?-bis(2-aminoethyl)-1,3-propanediamine (232), 1,2-bis(3-aminopropylamino)ethane (323), tetraethylenepentamine (TEPA) and pentaethylenehexamine (PEHA) have been investigated. For comparison, syntheses have been performed using the analogous nickel–polyamine complexes. Cu2+ and Ni2+ forms of both SAPO-18 and SAPO-34 materials have been prepared. While most polyamine complexes direct crystallisation to SAPO-34, SAPO-18 has been prepared with Cu2+(232), Ni2+(232) and Ni2+(TETA). The coordination geometry of the included metal complexes was studied by UV–visible and EPR spectroscopy and computer simulation. SAPO-18 is favoured by the smaller square planar complexes or octahedral species (with 2 water molecules) of 232 and TETA. Calcination leaves extra-framework Cu2+ and Ni2+ cations within SAPO-18 and SAPO-34 frameworks. In situ synchrotron IR spectroscopy of Ni-SAPO-18 has shown thermal template degradation occurs via nitrile intermediates. Rietveld structural analysis located extra-framework Cu2+ and Ni2+ cations released by calcination. In SAPO-34, Cu2+ and Ni2+ were located in the 8R window of the cha cage. A second site was found for Ni2+ at the centre of the six-membered rings (6Rs) of the double-six-ring (D6R) sub-units. In SAPO-18 both Cu2+ and Ni2+ cations were located only in the 6Rs of the D6R sub-units. Selected copper SAPO-18 and SAPO-34 samples were tested in the selective catalytic reduction of NO with ammonia (NH3-SCR); both showed high activity.

Journal Keywords: One-Pot Synthesis; Metal-Polyamine Complexes; Cu-Sapo-34; Cu-Sapo-18; Nh3-Scr

Subject Areas: Chemistry

Instruments: B22-Multimode InfraRed imaging And Microspectroscopy

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