Towards an understanding of the oxidation state of cobalt and manganese ions in framework substituted microporous aluminophosphate redox catalysts: An electron paramagnetic resonance and X-ray absorption spectroscopy investigation.
The local structure of manganese and cobalt ions in both the AlPO-5 and AlPO-18 materials was determined using electron paramagnetic resonance (EPR) and X-ray absorption spectroscopy (XAS). This study strongly suggested that both cobalt and manganese ions are present in the framework tetrahedral sites in the as-prepared materials. Upon calcination, in a dry atmosphere, both manganese and cobalt ions are partially oxidised to the 3+ state; the fraction of oxidised cobalt or manganese ions depends upon both the nature of the framework structure and on the ion type with manganese systems showing a higher proportion of oxidised cations.
Davy Faraday Research Laboratory, The Royal Institution of Great Britain, 21 Albemarle Street, London, UK W1S 4BS
Andrew M
AM
Beale
Gopinathan
G
Sankar
C Richard A
CR
Catlow
Paul A
PA
Anderson
Terry L
TL
Green
D017607:Aluminum Compounds / Q000737:chemistry; D002384:Catalysis; D003035:Cobalt / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D008345:Manganese / Q000737:chemistry*; D008968:Molecular Conformation; D010084:Oxidation-Reduction; D010710:Phosphates / Q000737:chemistry; D013052:Spectrometry, X-Ray Emission
D017607:Aluminum Compounds; D010710:Phosphates; D003035:Cobalt; D008345:Manganese; C012714:aluminum phosphate