TY - JOUR
T1 - Towards understanding the mechanism for the selective hydrogenation of maleic anhydride to tetrahydrofuran over palladium
AU - Pallassana, Venkataraman
AU - Neurock, Matthew
AU - Coulston, George
N1 - Copyright:
Copyright 2018 Elsevier B.V., All rights reserved.
PY - 1999/5/12
Y1 - 1999/5/12
N2 - First-principles density functional (DFT) quantum chemical calculations were carried out to understand the overall energetics for the hydrogenation of maleic anhydride to tetrahydrofuran (THF), over a Pd(1 1 1) cluster model. The calculated vapor phase structures and vibrational frequencies for maleic anhydride, succinic anhydride, γ-butyrolactone and THF compare well with the reported experimental X-ray crystal structure data and infrared (IR) frequency measurements. The overall reaction energies for vapor phase maleic anhydride hydrogenation to THF, determined using DFT, are within 5 kcal/ mol of the enthalpies of reaction, based on standard heats of formation. The adsorption structures for maleic anhydride, succinic anhydride, γ-butyrolactone, THF, water and atomic hydrogen were completely optimized on a fixed Pd(12,7) cluster model of the Pd(1 1 1) surface. The binding energies for maleic anhydride on the Pd19 cluster in the di-σ, π and η1 adsorption modes were -83, -34 and -28 kJ/mol, respectively. The computed adsorption energy and vibrational frequencies for di-σ bound maleic anhydride on Pd(1 1 1) are in good agreement with temperature-programmed desorption (TPD) and high-resolution electron energy loss spectroscopy (HREELS) measurements of Xu and Goodman [Langmuir 12 (1996) 1807-1816]. Preliminary calculations indicate that the most favorable adsorption mode for succinic anhydride, γ-butyrolactone, THF and water on Pd(1 1 1) is η1, with binding energies of -28, -38, -45 and -30 kJ/mol, respectively. The energetically most stable adsorption site for atomic hydrogen on the Pd(1 1 1) surface is the 3-fold fee site, with a binding energy of -257 kJ/mol. Towards understanding the detailed reaction mechanism on Pd(1 1 1), we have postulated elementary reaction pathways for C-H bond formation in maleic anhydride hydrogenation and the ring opening reaction of maleic anhydride on Pd(1 1 1). The DFT-computed activation barrier for C-H bond formation in maleic anhydride hydrogenation to maleic anhydryl on a Pd19 cluster is +82 kJ/mol and the energy of reaction is -9 kJ/mol. The ring opening reaction of maleic anhydride on Pd(1 1 1) has an activation barrier of +163 kJ/mol and is endothermic by 90 kJ/mol. The activation barrier on Re(0 0 0 1), however, is only +80 kJ/mol, whereas the reaction is exothermic by -96 kJ/mol. These results are consistent with the observations from UHV experiments.
AB - First-principles density functional (DFT) quantum chemical calculations were carried out to understand the overall energetics for the hydrogenation of maleic anhydride to tetrahydrofuran (THF), over a Pd(1 1 1) cluster model. The calculated vapor phase structures and vibrational frequencies for maleic anhydride, succinic anhydride, γ-butyrolactone and THF compare well with the reported experimental X-ray crystal structure data and infrared (IR) frequency measurements. The overall reaction energies for vapor phase maleic anhydride hydrogenation to THF, determined using DFT, are within 5 kcal/ mol of the enthalpies of reaction, based on standard heats of formation. The adsorption structures for maleic anhydride, succinic anhydride, γ-butyrolactone, THF, water and atomic hydrogen were completely optimized on a fixed Pd(12,7) cluster model of the Pd(1 1 1) surface. The binding energies for maleic anhydride on the Pd19 cluster in the di-σ, π and η1 adsorption modes were -83, -34 and -28 kJ/mol, respectively. The computed adsorption energy and vibrational frequencies for di-σ bound maleic anhydride on Pd(1 1 1) are in good agreement with temperature-programmed desorption (TPD) and high-resolution electron energy loss spectroscopy (HREELS) measurements of Xu and Goodman [Langmuir 12 (1996) 1807-1816]. Preliminary calculations indicate that the most favorable adsorption mode for succinic anhydride, γ-butyrolactone, THF and water on Pd(1 1 1) is η1, with binding energies of -28, -38, -45 and -30 kJ/mol, respectively. The energetically most stable adsorption site for atomic hydrogen on the Pd(1 1 1) surface is the 3-fold fee site, with a binding energy of -257 kJ/mol. Towards understanding the detailed reaction mechanism on Pd(1 1 1), we have postulated elementary reaction pathways for C-H bond formation in maleic anhydride hydrogenation and the ring opening reaction of maleic anhydride on Pd(1 1 1). The DFT-computed activation barrier for C-H bond formation in maleic anhydride hydrogenation to maleic anhydryl on a Pd19 cluster is +82 kJ/mol and the energy of reaction is -9 kJ/mol. The ring opening reaction of maleic anhydride on Pd(1 1 1) has an activation barrier of +163 kJ/mol and is endothermic by 90 kJ/mol. The activation barrier on Re(0 0 0 1), however, is only +80 kJ/mol, whereas the reaction is exothermic by -96 kJ/mol. These results are consistent with the observations from UHV experiments.
KW - Maleic anhydride
KW - Selective hydrogenation
KW - Tetrahydrofuran
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U2 - 10.1016/S0920-5861(98)00493-3
DO - 10.1016/S0920-5861(98)00493-3
M3 - Article
AN - SCOPUS:0000588088
SN - 0920-5861
VL - 50
SP - 589
EP - 601
JO - Catalysis Today
JF - Catalysis Today
IS - 3-4
ER -