X-ray absorption spectroscopy of Mn/Co/TiO2 Fischer-Tropsch catalysts: relationships between preparation method, molecular structure, and catalyst performance

The Journal of Physical Chemistry. B
Fernando MoralesBert M Weckhuysen

Abstract

The effects of the addition of manganese to a series of TiO(2)-supported cobalt Fischer-Tropsch (FT) catalysts prepared by different methods were studied by a combination of X-ray diffraction (XRD), temperature-programmed reduction (TPR), transmission electron microscopy (TEM), and in situ X-ray absorption fine structure (XAFS) spectroscopy at the Co and Mn K-edges. After calcination, the catalysts were generally composed of large Co(3)O(4) clusters in the range 15-35 nm and a MnO(2)-type phase, which existed either dispersed on the TiO(2) surface or covering the Co(3)O(4) particles. Manganese was also found to coexist with the Co(3)O(4) in the form of Co(3-x)Mn(x)O(4) solutions, as revealed by XRD and XAFS. Characterization of the catalysts after H(2) reduction at 350 degrees C by XAFS and TEM showed mostly the formation of very small Co(0) particles (around 2-6 nm), indicating that the cobalt phase tends to redisperse during the reduction process from Co(3)O(4) to Co(0). The presence of manganese was found to hamper the cobalt reducibility, with this effect being more severe when Co(3-x)Mn(x)O(4) solutions were initially present in the catalyst precursors. Moreover, the presence of manganese generally led to the formation of ...Continue Reading

References

Mar 23, 2006·Journal of the American Chemical Society·G Leendert BezemerKrijn P de Jong
Feb 21, 2005·Physical Chemistry Chemical Physics : PCCP·Fernando MoralesBert M Weckhuysen

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Citations

Apr 10, 2010·Physical Chemistry Chemical Physics : PCCP·Andrew M Beale, Bert M Weckhuysen
Oct 17, 2009·Chemistry : a European Journal·Theano PetsiKyriakos Bourikas
Feb 8, 2020·Chemical Communications : Chem Comm·Ryan A CiufoC Buddie Mullins
Apr 16, 2013·Chemical Communications : Chem Comm·Korneel H CatsBert M Weckhuysen
May 18, 2013·Langmuir : the ACS Journal of Surfaces and Colloids·Supattra KhabuanchaladBruce C Gates
Dec 19, 2012··Aloysius HeppRobert Zubrin
Dec 18, 2012··Richard Gonzalez-ArroyoLauren Best

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