Tuning Zr6 Metal-Organic Framework (MOF) Nodes as Catalyst Supports: Site Densities and Electron-Donor Properties Influence Molecular Iridium Complexes as Ethylene Conversion Catalysts

Dong Yang, Samuel O. Odoh, Joshua Borycz, Timothy C. Wang, Omar K. Farha, Joseph T Hupp, Christopher J. Cramer, Laura Gagliardi, Bruce C. Gates

Research output: Contribution to journalArticle

66 Citations (Scopus)

Abstract

The Zr6 nodes of the metal-organic frameworks (MOFs) UiO-66 and UiO-67 are metal oxide clusters of atomic precision and can be used as catalyst supports. The bonding sites on these nodes - that is, hydrogen-bonded H2O/OH groups on UiO-67 and non-hydrogen-bonded terminal OH groups on UiO-66 - were regulated by modulation of the MOF syntheses. Ir(C2H4)2(C5H7O2) complexes reacted with these sites to give site-isolated Ir(C2H4)2 complexes, each anchored to the node by two Ir-Onode bonds. The supported iridium complexes on these sites have been characterized by infrared (IR) and extended X-ray absorption fine structure (EXAFS) spectroscopies and density functional theory calculations. The ethylene ligands on iridium are readily replaced by CO, and the νCO frequencies of the resultant complexes and those of comparable complexes reported elsewhere show that the support electron-donor tendencies increase in the order HY zeolite 蠐 UiO-66 <UiO-67 (= NU-1000) <ZrO2 <MgO. The sharpness of the IR νCO bands shows that the degree of uniformity of the support bonding sites decreases in the order ZrO2 ≈ UiO-67 ≈ NU-1000 <MgO <UiO-66 蠐 HY zeolite. The reactivity of supported Ir(CO)2 complexes with C2H4 to form Ir(C2H4)(CO) and Ir(C2H4)2(CO) is influenced by the support electron-donor properties, with the reactivity increasing in the order MgO = ZrO2 = NU-1000 (not reactive) <UiO-66 <UiO-67 蠐 HY zeolite. Density functional theory calculations characterizing the complexes supported on NU-1000, UiO-66/67, and HY zeolite concur with the use of the calculated νCO bands as indicators of electron-donor properties of the supported metal catalysts. Our calculations also show that the reactivity of the supported Ir(CO)2 complexes with C2H4 is correlated with the electron-donor properties of the iridium center. The supported Ir(C2H4)2 samples are precatalysts for ethylene hydrogenation and ethylene dimerization, with the activity for each reaction increasing with increasing electron-withdrawing strength of the support.

Original languageEnglish
Pages (from-to)235-247
Number of pages13
JournalACS Catalysis
Volume6
Issue number1
DOIs
Publication statusPublished - Jan 4 2016

Fingerprint

Iridium
Carbon Monoxide
Catalyst supports
Ethylene
Tuning
Metals
Zeolites
Catalysts
Electrons
Density functional theory
Extended X ray absorption fine structure spectroscopy
Infrared radiation
Dimerization
Hydrogenation
Ligands
Modulation
ethylene
Hydrogen
Oxides

Keywords

  • catalyst supports
  • ethylene dimerization
  • ethylene hydrogenation
  • iridium carbonyl complexes
  • iridium ethylene complexes
  • metal-organic framework nodes

ASJC Scopus subject areas

  • Catalysis

Cite this

Tuning Zr6 Metal-Organic Framework (MOF) Nodes as Catalyst Supports : Site Densities and Electron-Donor Properties Influence Molecular Iridium Complexes as Ethylene Conversion Catalysts. / Yang, Dong; Odoh, Samuel O.; Borycz, Joshua; Wang, Timothy C.; Farha, Omar K.; Hupp, Joseph T; Cramer, Christopher J.; Gagliardi, Laura; Gates, Bruce C.

In: ACS Catalysis, Vol. 6, No. 1, 04.01.2016, p. 235-247.

Research output: Contribution to journalArticle

Yang, Dong ; Odoh, Samuel O. ; Borycz, Joshua ; Wang, Timothy C. ; Farha, Omar K. ; Hupp, Joseph T ; Cramer, Christopher J. ; Gagliardi, Laura ; Gates, Bruce C. / Tuning Zr6 Metal-Organic Framework (MOF) Nodes as Catalyst Supports : Site Densities and Electron-Donor Properties Influence Molecular Iridium Complexes as Ethylene Conversion Catalysts. In: ACS Catalysis. 2016 ; Vol. 6, No. 1. pp. 235-247.
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abstract = "The Zr6 nodes of the metal-organic frameworks (MOFs) UiO-66 and UiO-67 are metal oxide clusters of atomic precision and can be used as catalyst supports. The bonding sites on these nodes - that is, hydrogen-bonded H2O/OH groups on UiO-67 and non-hydrogen-bonded terminal OH groups on UiO-66 - were regulated by modulation of the MOF syntheses. Ir(C2H4)2(C5H7O2) complexes reacted with these sites to give site-isolated Ir(C2H4)2 complexes, each anchored to the node by two Ir-Onode bonds. The supported iridium complexes on these sites have been characterized by infrared (IR) and extended X-ray absorption fine structure (EXAFS) spectroscopies and density functional theory calculations. The ethylene ligands on iridium are readily replaced by CO, and the νCO frequencies of the resultant complexes and those of comparable complexes reported elsewhere show that the support electron-donor tendencies increase in the order HY zeolite 蠐 UiO-66 <UiO-67 (= NU-1000) <ZrO2 <MgO. The sharpness of the IR νCO bands shows that the degree of uniformity of the support bonding sites decreases in the order ZrO2 ≈ UiO-67 ≈ NU-1000 <MgO <UiO-66 蠐 HY zeolite. The reactivity of supported Ir(CO)2 complexes with C2H4 to form Ir(C2H4)(CO) and Ir(C2H4)2(CO) is influenced by the support electron-donor properties, with the reactivity increasing in the order MgO = ZrO2 = NU-1000 (not reactive) <UiO-66 <UiO-67 蠐 HY zeolite. Density functional theory calculations characterizing the complexes supported on NU-1000, UiO-66/67, and HY zeolite concur with the use of the calculated νCO bands as indicators of electron-donor properties of the supported metal catalysts. Our calculations also show that the reactivity of the supported Ir(CO)2 complexes with C2H4 is correlated with the electron-donor properties of the iridium center. The supported Ir(C2H4)2 samples are precatalysts for ethylene hydrogenation and ethylene dimerization, with the activity for each reaction increasing with increasing electron-withdrawing strength of the support.",
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T1 - Tuning Zr6 Metal-Organic Framework (MOF) Nodes as Catalyst Supports

T2 - Site Densities and Electron-Donor Properties Influence Molecular Iridium Complexes as Ethylene Conversion Catalysts

AU - Yang, Dong

AU - Odoh, Samuel O.

AU - Borycz, Joshua

AU - Wang, Timothy C.

AU - Farha, Omar K.

AU - Hupp, Joseph T

AU - Cramer, Christopher J.

AU - Gagliardi, Laura

AU - Gates, Bruce C.

PY - 2016/1/4

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N2 - The Zr6 nodes of the metal-organic frameworks (MOFs) UiO-66 and UiO-67 are metal oxide clusters of atomic precision and can be used as catalyst supports. The bonding sites on these nodes - that is, hydrogen-bonded H2O/OH groups on UiO-67 and non-hydrogen-bonded terminal OH groups on UiO-66 - were regulated by modulation of the MOF syntheses. Ir(C2H4)2(C5H7O2) complexes reacted with these sites to give site-isolated Ir(C2H4)2 complexes, each anchored to the node by two Ir-Onode bonds. The supported iridium complexes on these sites have been characterized by infrared (IR) and extended X-ray absorption fine structure (EXAFS) spectroscopies and density functional theory calculations. The ethylene ligands on iridium are readily replaced by CO, and the νCO frequencies of the resultant complexes and those of comparable complexes reported elsewhere show that the support electron-donor tendencies increase in the order HY zeolite 蠐 UiO-66 <UiO-67 (= NU-1000) <ZrO2 <MgO. The sharpness of the IR νCO bands shows that the degree of uniformity of the support bonding sites decreases in the order ZrO2 ≈ UiO-67 ≈ NU-1000 <MgO <UiO-66 蠐 HY zeolite. The reactivity of supported Ir(CO)2 complexes with C2H4 to form Ir(C2H4)(CO) and Ir(C2H4)2(CO) is influenced by the support electron-donor properties, with the reactivity increasing in the order MgO = ZrO2 = NU-1000 (not reactive) <UiO-66 <UiO-67 蠐 HY zeolite. Density functional theory calculations characterizing the complexes supported on NU-1000, UiO-66/67, and HY zeolite concur with the use of the calculated νCO bands as indicators of electron-donor properties of the supported metal catalysts. Our calculations also show that the reactivity of the supported Ir(CO)2 complexes with C2H4 is correlated with the electron-donor properties of the iridium center. The supported Ir(C2H4)2 samples are precatalysts for ethylene hydrogenation and ethylene dimerization, with the activity for each reaction increasing with increasing electron-withdrawing strength of the support.

AB - The Zr6 nodes of the metal-organic frameworks (MOFs) UiO-66 and UiO-67 are metal oxide clusters of atomic precision and can be used as catalyst supports. The bonding sites on these nodes - that is, hydrogen-bonded H2O/OH groups on UiO-67 and non-hydrogen-bonded terminal OH groups on UiO-66 - were regulated by modulation of the MOF syntheses. Ir(C2H4)2(C5H7O2) complexes reacted with these sites to give site-isolated Ir(C2H4)2 complexes, each anchored to the node by two Ir-Onode bonds. The supported iridium complexes on these sites have been characterized by infrared (IR) and extended X-ray absorption fine structure (EXAFS) spectroscopies and density functional theory calculations. The ethylene ligands on iridium are readily replaced by CO, and the νCO frequencies of the resultant complexes and those of comparable complexes reported elsewhere show that the support electron-donor tendencies increase in the order HY zeolite 蠐 UiO-66 <UiO-67 (= NU-1000) <ZrO2 <MgO. The sharpness of the IR νCO bands shows that the degree of uniformity of the support bonding sites decreases in the order ZrO2 ≈ UiO-67 ≈ NU-1000 <MgO <UiO-66 蠐 HY zeolite. The reactivity of supported Ir(CO)2 complexes with C2H4 to form Ir(C2H4)(CO) and Ir(C2H4)2(CO) is influenced by the support electron-donor properties, with the reactivity increasing in the order MgO = ZrO2 = NU-1000 (not reactive) <UiO-66 <UiO-67 蠐 HY zeolite. Density functional theory calculations characterizing the complexes supported on NU-1000, UiO-66/67, and HY zeolite concur with the use of the calculated νCO bands as indicators of electron-donor properties of the supported metal catalysts. Our calculations also show that the reactivity of the supported Ir(CO)2 complexes with C2H4 is correlated with the electron-donor properties of the iridium center. The supported Ir(C2H4)2 samples are precatalysts for ethylene hydrogenation and ethylene dimerization, with the activity for each reaction increasing with increasing electron-withdrawing strength of the support.

KW - catalyst supports

KW - ethylene dimerization

KW - ethylene hydrogenation

KW - iridium carbonyl complexes

KW - iridium ethylene complexes

KW - metal-organic framework nodes

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