TY - JOUR
T1 - Propane Dehydrogenation to Propylene and Propylene Adsorption on Ni and Ni-Sn Catalysts
AU - Robbins, Jason P.
AU - Ezeonu, Lotanna
AU - Tang, Ziyu
AU - Yang, Xiaofang
AU - Koel, Bruce E.
AU - Podkolzin, Simon G.
N1 - Funding Information:
This research was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award DE‐SC0019052. The DFT calculations were performed with the Materials Studio software provided by Dassault Systèmes BIOVIA Corporation under a collaborative research agreement. We thank Dr. Felix Hanke and Dr. Victor Milman at Dassault Systèmes BIOVIA Corporation for discussions on the computational settings. We thank Dr. Tseng‐Ming Chou at Stevens Institute of Technology for help with TEM measurements.
Publisher Copyright:
© 2022 Wiley-VCH GmbH.
PY - 2022/3/22
Y1 - 2022/3/22
N2 - Temperature programmed reaction (TPR) measurements with propane over silica-supported Ni, Ni−Sn and Sn catalysts show that the reaction products change significantly from mostly methane, hydrogen and surface carbon over Ni to propylene and hydrogen over Ni−Sn. Propylene formation over Ni−Sn starts at a moderate temperature of 630 K. Since the activity of Sn by itself is low, Sn serves as a promoter for Ni. The promoter effects are attributed to a lower adsorption energy of molecularly adsorbed propylene and suppression of propylidyne formation on Ni−Sn based on temperature programmed desorption (TPD) and infrared reflection absorption spectroscopy (IRAS) measurements as well as density functional theory (DFT) calculations for propylene adsorption on Ni(110) and c(2×2)-Sn/Ni(110) single-crystal surfaces. On Ni, propylene forms a π-bonded structure with ν(C=C) at 1500 cm−1, which desorbs at 170 K, and a di-σ-bonded structure with ν(C=C) at 1416 cm−1, which desorbs at 245 K. The di-σ-bonded structure is asymmetric, with the methylene C atom being in the middle of the Ni−Ni bridge site, and the methylidyne C atom being above one of these Ni atoms. Therefore, this structure can also be characterized as a hybrid between di-σ- and π-bonded structures. Only a fraction of propylene desorbs from Ni because propylene can convert into propylidyne, which decomposes further. In contrast, propylene forms only a π-bonded structure on Ni−Sn with ν(C=C) at 1506 cm−1, which desorbs at 125 K. The low stability of this structure enables propylene to desorb fully, resulting in high reaction selectivity in propane dehydrogenation to propylene over the Ni−Sn catalyst.
AB - Temperature programmed reaction (TPR) measurements with propane over silica-supported Ni, Ni−Sn and Sn catalysts show that the reaction products change significantly from mostly methane, hydrogen and surface carbon over Ni to propylene and hydrogen over Ni−Sn. Propylene formation over Ni−Sn starts at a moderate temperature of 630 K. Since the activity of Sn by itself is low, Sn serves as a promoter for Ni. The promoter effects are attributed to a lower adsorption energy of molecularly adsorbed propylene and suppression of propylidyne formation on Ni−Sn based on temperature programmed desorption (TPD) and infrared reflection absorption spectroscopy (IRAS) measurements as well as density functional theory (DFT) calculations for propylene adsorption on Ni(110) and c(2×2)-Sn/Ni(110) single-crystal surfaces. On Ni, propylene forms a π-bonded structure with ν(C=C) at 1500 cm−1, which desorbs at 170 K, and a di-σ-bonded structure with ν(C=C) at 1416 cm−1, which desorbs at 245 K. The di-σ-bonded structure is asymmetric, with the methylene C atom being in the middle of the Ni−Ni bridge site, and the methylidyne C atom being above one of these Ni atoms. Therefore, this structure can also be characterized as a hybrid between di-σ- and π-bonded structures. Only a fraction of propylene desorbs from Ni because propylene can convert into propylidyne, which decomposes further. In contrast, propylene forms only a π-bonded structure on Ni−Sn with ν(C=C) at 1506 cm−1, which desorbs at 125 K. The low stability of this structure enables propylene to desorb fully, resulting in high reaction selectivity in propane dehydrogenation to propylene over the Ni−Sn catalyst.
KW - Bimetallic, nickel, propene, spectroscopy, tin
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U2 - 10.1002/cctc.202101546
DO - 10.1002/cctc.202101546
M3 - Article
AN - SCOPUS:85123860581
SN - 1867-3880
VL - 14
JO - ChemCatChem
JF - ChemCatChem
IS - 6
M1 - e202101546
ER -