Abstract
Quantifying specific active sites in supported catalysts improves our understanding and assists in rational design. Supported oxides can undergo significant structural changes as surface densities increase from site-isolated cations to monolayers and crystallites, which changes the number of kinetically relevant sites. Herein, TiOx domains are titrated on TiOx-SiO2 selectively with phenylphosphonic acid (PPA). An ex situ method quantifies all fluid-accessible TiOx, whereas an in situ titration during cis-cyclooctene epoxidation provides previously unavailable values for the number of tetrahedral Ti sites on which H2O2activation occurs. We use this method to determine the active site densities of 22 different catalysts with different synthesis methods, loadings, and characteristic spectra and find a single intrinsic turnover frequency for cis-cyclooctene epoxidation of (40± 7) h-1. This simple method gives molecular-level insight into catalyst structure that is otherwise hidden when bulk techniques are used.
| Original language | English |
|---|---|
| Pages (from-to) | 3215-3222 |
| Number of pages | 8 |
| Journal | ChemCatChem |
| Volume | 6 |
| Issue number | 11 |
| DOIs | |
| Publication status | Published - 2014 |
Fingerprint
Keywords
- Epoxidation
- Heterogeneous catalysis
- Structure-activity relationships
- Supported catalysts
- Titanium
ASJC Scopus subject areas
- Inorganic Chemistry
- Organic Chemistry
- Physical and Theoretical Chemistry
- Catalysis
Cite this
Counting active sites on titanium oxide-silica catalysts for hydrogen peroxide activation through in situ poisoning with phenylphosphonic acid. / Eaton, Todd R.; Boston, Andrew M.; Thompson, Anthony B.; Gray, Kimberly A.; Notestein, Justin M.
In: ChemCatChem, Vol. 6, No. 11, 2014, p. 3215-3222.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Counting active sites on titanium oxide-silica catalysts for hydrogen peroxide activation through in situ poisoning with phenylphosphonic acid
AU - Eaton, Todd R.
AU - Boston, Andrew M.
AU - Thompson, Anthony B.
AU - Gray, Kimberly A.
AU - Notestein, Justin M
PY - 2014
Y1 - 2014
N2 - Quantifying specific active sites in supported catalysts improves our understanding and assists in rational design. Supported oxides can undergo significant structural changes as surface densities increase from site-isolated cations to monolayers and crystallites, which changes the number of kinetically relevant sites. Herein, TiOx domains are titrated on TiOx-SiO2 selectively with phenylphosphonic acid (PPA). An ex situ method quantifies all fluid-accessible TiOx, whereas an in situ titration during cis-cyclooctene epoxidation provides previously unavailable values for the number of tetrahedral Ti sites on which H2O2activation occurs. We use this method to determine the active site densities of 22 different catalysts with different synthesis methods, loadings, and characteristic spectra and find a single intrinsic turnover frequency for cis-cyclooctene epoxidation of (40± 7) h-1. This simple method gives molecular-level insight into catalyst structure that is otherwise hidden when bulk techniques are used.
AB - Quantifying specific active sites in supported catalysts improves our understanding and assists in rational design. Supported oxides can undergo significant structural changes as surface densities increase from site-isolated cations to monolayers and crystallites, which changes the number of kinetically relevant sites. Herein, TiOx domains are titrated on TiOx-SiO2 selectively with phenylphosphonic acid (PPA). An ex situ method quantifies all fluid-accessible TiOx, whereas an in situ titration during cis-cyclooctene epoxidation provides previously unavailable values for the number of tetrahedral Ti sites on which H2O2activation occurs. We use this method to determine the active site densities of 22 different catalysts with different synthesis methods, loadings, and characteristic spectra and find a single intrinsic turnover frequency for cis-cyclooctene epoxidation of (40± 7) h-1. This simple method gives molecular-level insight into catalyst structure that is otherwise hidden when bulk techniques are used.
KW - Epoxidation
KW - Heterogeneous catalysis
KW - Structure-activity relationships
KW - Supported catalysts
KW - Titanium
UR - http://www.scopus.com/inward/record.url?scp=84915805544&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84915805544&partnerID=8YFLogxK
U2 - 10.1002/cctc.201402611
DO - 10.1002/cctc.201402611
M3 - Article
VL - 6
SP - 3215
EP - 3222
JO - ChemCatChem
JF - ChemCatChem
SN - 1867-3880
IS - 11
ER -