TY - JOUR
T1 - Fischer–Tropsch Synthesis
T2 - Effect of the Promoter’s Ionic Charge and Valence Level Energy on Activity
AU - Ribeiro, Mirtha Z.Leguizamón León
AU - Souza, Joice C.
AU - Gnanamani, Muthu Kumaran
AU - Martinelli, Michela
AU - Upton, Gabriel F.
AU - Jacobs, Gary
AU - Ribeiro, Mauro C.
N1 - Publisher Copyright:
© 2021 by the authors.
PY - 2021/12
Y1 - 2021/12
N2 - In this contribution, we examine the effect of the promoter´s ionic charge and valence orbital energy on the catalytic activity of Fe-based catalysts, based on in situ synchrotron X-ray powder diffraction (SXRPD), temperature-programmed-based techniques (TPR, TPD, CO-TP carburization), and Fischer–Tropsch synthesis catalytic testing studies. We compared the promoting effects of K (a known promoter for longer-chained products) with Ba, which has a similar ionic radius but has double the ionic charge. Despite being partially “buried” in a crystalline BaCO3 phase, the carburization of the Ba-promoted catalyst was more effective than that of K; this was primarily due to its higher (2+) ionic charge. With Ba2+, higher selectivity to methane and lighter products were obtained compared to the K-promoted catalysts; this is likely due to Ba´s lesser capability of suppressing H adsorption on the catalyst surface. An explanation is provided in terms of a more limited mixing between electron-filled Ba2+ 5p and partially filled Fe 3d orbitals, which are expected to be important for the chemical promotion, as they are further apart in energy compared to the K+ 3p and Fe 3d orbitals.
AB - In this contribution, we examine the effect of the promoter´s ionic charge and valence orbital energy on the catalytic activity of Fe-based catalysts, based on in situ synchrotron X-ray powder diffraction (SXRPD), temperature-programmed-based techniques (TPR, TPD, CO-TP carburization), and Fischer–Tropsch synthesis catalytic testing studies. We compared the promoting effects of K (a known promoter for longer-chained products) with Ba, which has a similar ionic radius but has double the ionic charge. Despite being partially “buried” in a crystalline BaCO3 phase, the carburization of the Ba-promoted catalyst was more effective than that of K; this was primarily due to its higher (2+) ionic charge. With Ba2+, higher selectivity to methane and lighter products were obtained compared to the K-promoted catalysts; this is likely due to Ba´s lesser capability of suppressing H adsorption on the catalyst surface. An explanation is provided in terms of a more limited mixing between electron-filled Ba2+ 5p and partially filled Fe 3d orbitals, which are expected to be important for the chemical promotion, as they are further apart in energy compared to the K+ 3p and Fe 3d orbitals.
KW - alkali
KW - alkali-earth
KW - Fischer–Tropsch synthesis
KW - ion valance
KW - iron
KW - promoter
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U2 - 10.3390/reactions2040026
DO - 10.3390/reactions2040026
M3 - Article
AN - SCOPUS:85140764545
SN - 2624-781X
VL - 2
SP - 408
EP - 426
JO - Reactions
JF - Reactions
IS - 4
ER -