Abstract
Here, we report on structure-reactivity trends for cyclohexane oxidative dehydrogenation (ODH) with silica supported copper oxide catalysts as a function of surface structure. Copper oxide was supported on mesostructured KIT-6 silica at low surface densities 2 using copper (II) nitrate, ammonium and sodium copper (II) ethylenediaminetetraacetate, and a hexanuclear copper (I) siloxide complex. Copper oxide surface structures were characterized by X-ray absorption spectroscopy as well as ambient and in situ diffuse reflectance UV–visible (DRUV–vis) spectroscopy to determine trends in copper oxide nuclearity. DRUV–vis spectroscopy identifies three copper species based on Cu2+ ligand to metal transfer (LMCT) bands at 238, 266, and >300 nm as well as Cu+ LMCT bands at 235, 296, and 312 nm. Counterintuitively, EXAFS analysis shows that the multinuclear precursor leads to fewer average Cu–Cu interactions than syntheses with mononuclear copper salt precursors. Turnover frequency and selectivity to benzene increase with decreasing copper oxide nuclearity, and thus the multinuclear precursor leads to the highest turnover frequency and benzene production. This work shows the variety of surface species that exist even at extremely low copper surface densities, control of which can improve reactivity of an atypical ODH catalyst up to rates comparable to benchmark vanadia catalysts.
| Original language | English |
|---|---|
| Pages (from-to) | 180-190 |
| Number of pages | 11 |
| Journal | Journal of Catalysis |
| Volume | 341 |
| DOIs | |
| Publication status | Published - Sep 1 2016 |
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Keywords
- Copper oxide
- Cyclohexane
- KIT-6
- Oxidative dehydrogenation
ASJC Scopus subject areas
- Catalysis
- Physical and Theoretical Chemistry
Cite this
Cyclohexane oxidative dehydrogenation over copper oxide catalysts. / Nauert, Scott L.; Schax, Fabian; Limberg, Christian; Notestein, Justin M.
In: Journal of Catalysis, Vol. 341, 01.09.2016, p. 180-190.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Cyclohexane oxidative dehydrogenation over copper oxide catalysts
AU - Nauert, Scott L.
AU - Schax, Fabian
AU - Limberg, Christian
AU - Notestein, Justin M
PY - 2016/9/1
Y1 - 2016/9/1
N2 - Here, we report on structure-reactivity trends for cyclohexane oxidative dehydrogenation (ODH) with silica supported copper oxide catalysts as a function of surface structure. Copper oxide was supported on mesostructured KIT-6 silica at low surface densities 2 using copper (II) nitrate, ammonium and sodium copper (II) ethylenediaminetetraacetate, and a hexanuclear copper (I) siloxide complex. Copper oxide surface structures were characterized by X-ray absorption spectroscopy as well as ambient and in situ diffuse reflectance UV–visible (DRUV–vis) spectroscopy to determine trends in copper oxide nuclearity. DRUV–vis spectroscopy identifies three copper species based on Cu2+ ligand to metal transfer (LMCT) bands at 238, 266, and >300 nm as well as Cu+ LMCT bands at 235, 296, and 312 nm. Counterintuitively, EXAFS analysis shows that the multinuclear precursor leads to fewer average Cu–Cu interactions than syntheses with mononuclear copper salt precursors. Turnover frequency and selectivity to benzene increase with decreasing copper oxide nuclearity, and thus the multinuclear precursor leads to the highest turnover frequency and benzene production. This work shows the variety of surface species that exist even at extremely low copper surface densities, control of which can improve reactivity of an atypical ODH catalyst up to rates comparable to benchmark vanadia catalysts.
AB - Here, we report on structure-reactivity trends for cyclohexane oxidative dehydrogenation (ODH) with silica supported copper oxide catalysts as a function of surface structure. Copper oxide was supported on mesostructured KIT-6 silica at low surface densities 2 using copper (II) nitrate, ammonium and sodium copper (II) ethylenediaminetetraacetate, and a hexanuclear copper (I) siloxide complex. Copper oxide surface structures were characterized by X-ray absorption spectroscopy as well as ambient and in situ diffuse reflectance UV–visible (DRUV–vis) spectroscopy to determine trends in copper oxide nuclearity. DRUV–vis spectroscopy identifies three copper species based on Cu2+ ligand to metal transfer (LMCT) bands at 238, 266, and >300 nm as well as Cu+ LMCT bands at 235, 296, and 312 nm. Counterintuitively, EXAFS analysis shows that the multinuclear precursor leads to fewer average Cu–Cu interactions than syntheses with mononuclear copper salt precursors. Turnover frequency and selectivity to benzene increase with decreasing copper oxide nuclearity, and thus the multinuclear precursor leads to the highest turnover frequency and benzene production. This work shows the variety of surface species that exist even at extremely low copper surface densities, control of which can improve reactivity of an atypical ODH catalyst up to rates comparable to benchmark vanadia catalysts.
KW - Copper oxide
KW - Cyclohexane
KW - KIT-6
KW - Oxidative dehydrogenation
UR - http://www.scopus.com/inward/record.url?scp=84979755892&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84979755892&partnerID=8YFLogxK
U2 - 10.1016/j.jcat.2016.07.002
DO - 10.1016/j.jcat.2016.07.002
M3 - Article
AN - SCOPUS:84979755892
VL - 341
SP - 180
EP - 190
JO - Journal of Catalysis
JF - Journal of Catalysis
SN - 0021-9517
ER -