Uittreksel
Achieving uniformly dispersed and stable nanoparticles of gold on oxide supports is a challenge in heterogeneous catalysis. Here, we show that zincochromite (ZnCr2O4) is a promising support for obtaining high and stable gold dispersion. Despite a low surface area of ZnCr2O4, finely dispersed gold (∼3-4 nm particles) could be obtained by a simple deposition-precipitation method, pointing to strong gold-support interactions. Using a combination of XRD, XPS, SEM, TEM, HAADF-STEM, and IR spectroscopy, we confirmed that the calcination temperature of the ZnCr2O4 support had a substantial influence on the crystallinity, morphology, and acidic properties of thereof derived Au/ZnCr2O4 catalysts. Gold supported on a high-temperature (≥700 °C) calcined ZnCr2O4 support displayed the best catalytic performance in gas-phase oxidation of cyclohexanol to cyclohexanone, which is an important intermediate in the chemical industry. When calcined at 800 °C, the material did not show any sign of deactivation in a 90 h stability test, high cyclohexanol conversion (93%) and high cyclohexanone yield (91%) were achieved at 300 °C, with a space-time yield of 250 gproduct gAu-1 h-1. On the contrary, Au/ZnCr2O4 based on supports calcined at lower temperatures (≤600 °C) catalyzed side reactions such as cyclohexanol dehydration to cyclohexene (Lewis acid sites), which further oligomerized to coke deposits that deactivated the catalyst. The CO oxidation trends with respect to calcination temperature were inversed to those in cyclohexanol oxidation, showing that smaller gold particles and the presence of hydroxyls are favorable for CO oxidation to CO2. DFT calculations provided insight into the (electronic) nature of the strong interactions between Au and ZnCr2O4
| Originele taal-2 | Engels |
|---|---|
| Pagina's (van-tot) | 11104-11115 |
| Aantal pagina's | 12 |
| Tijdschrift | ACS Catalysis |
| Volume | 9 |
| Nummer van het tijdschrift | 12 |
| DOI's | |
| Status | Gepubliceerd - dec 2019 |
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A robust Au/ZnCr2O4 catalyst with highly dispersed gold nanoparticles for gas-phase selective oxidation of cyclohexanol to cyclohexanone. / Gao, Yanan; Zhang, Long; Van Hoof, Arno J.F.; Friedrich, Heiner; Hensen, Emiel J.M. (Corresponding author).
In: ACS Catalysis, Vol. 9, Nr. 12, 12.2019, blz. 11104-11115.Onderzoeksoutput: Bijdrage aan tijdschrift › Tijdschriftartikel › Academic › peer review
TY - JOUR
T1 - A robust Au/ZnCr2O4 catalyst with highly dispersed gold nanoparticles for gas-phase selective oxidation of cyclohexanol to cyclohexanone
AU - Gao, Yanan
AU - Zhang, Long
AU - Van Hoof, Arno J.F.
AU - Friedrich, Heiner
AU - Hensen, Emiel J.M.
PY - 2019/12
Y1 - 2019/12
N2 - Achieving uniformly dispersed and stable nanoparticles of gold on oxide supports is a challenge in heterogeneous catalysis. Here, we show that zincochromite (ZnCr2O4) is a promising support for obtaining high and stable gold dispersion. Despite a low surface area of ZnCr2O4, finely dispersed gold (∼3-4 nm particles) could be obtained by a simple deposition-precipitation method, pointing to strong gold-support interactions. Using a combination of XRD, XPS, SEM, TEM, HAADF-STEM, and IR spectroscopy, we confirmed that the calcination temperature of the ZnCr2O4 support had a substantial influence on the crystallinity, morphology, and acidic properties of thereof derived Au/ZnCr2O4 catalysts. Gold supported on a high-temperature (≥700 °C) calcined ZnCr2O4 support displayed the best catalytic performance in gas-phase oxidation of cyclohexanol to cyclohexanone, which is an important intermediate in the chemical industry. When calcined at 800 °C, the material did not show any sign of deactivation in a 90 h stability test, high cyclohexanol conversion (93%) and high cyclohexanone yield (91%) were achieved at 300 °C, with a space-time yield of 250 gproduct gAu-1 h-1. On the contrary, Au/ZnCr2O4 based on supports calcined at lower temperatures (≤600 °C) catalyzed side reactions such as cyclohexanol dehydration to cyclohexene (Lewis acid sites), which further oligomerized to coke deposits that deactivated the catalyst. The CO oxidation trends with respect to calcination temperature were inversed to those in cyclohexanol oxidation, showing that smaller gold particles and the presence of hydroxyls are favorable for CO oxidation to CO2. DFT calculations provided insight into the (electronic) nature of the strong interactions between Au and ZnCr2O4
AB - Achieving uniformly dispersed and stable nanoparticles of gold on oxide supports is a challenge in heterogeneous catalysis. Here, we show that zincochromite (ZnCr2O4) is a promising support for obtaining high and stable gold dispersion. Despite a low surface area of ZnCr2O4, finely dispersed gold (∼3-4 nm particles) could be obtained by a simple deposition-precipitation method, pointing to strong gold-support interactions. Using a combination of XRD, XPS, SEM, TEM, HAADF-STEM, and IR spectroscopy, we confirmed that the calcination temperature of the ZnCr2O4 support had a substantial influence on the crystallinity, morphology, and acidic properties of thereof derived Au/ZnCr2O4 catalysts. Gold supported on a high-temperature (≥700 °C) calcined ZnCr2O4 support displayed the best catalytic performance in gas-phase oxidation of cyclohexanol to cyclohexanone, which is an important intermediate in the chemical industry. When calcined at 800 °C, the material did not show any sign of deactivation in a 90 h stability test, high cyclohexanol conversion (93%) and high cyclohexanone yield (91%) were achieved at 300 °C, with a space-time yield of 250 gproduct gAu-1 h-1. On the contrary, Au/ZnCr2O4 based on supports calcined at lower temperatures (≤600 °C) catalyzed side reactions such as cyclohexanol dehydration to cyclohexene (Lewis acid sites), which further oligomerized to coke deposits that deactivated the catalyst. The CO oxidation trends with respect to calcination temperature were inversed to those in cyclohexanol oxidation, showing that smaller gold particles and the presence of hydroxyls are favorable for CO oxidation to CO2. DFT calculations provided insight into the (electronic) nature of the strong interactions between Au and ZnCr2O4
KW - cyclohexanol
KW - cyclohexanone
KW - gold
KW - metal-support interactions
KW - ZnCrO
KW - ZnCr2O4
UR - http://www.scopus.com/inward/record.url?scp=85074797185&partnerID=8YFLogxK
U2 - 10.1021/acscatal.9b02821
DO - 10.1021/acscatal.9b02821
M3 - Article
AN - SCOPUS:85074797185
VL - 9
SP - 11104
EP - 11115
JO - ACS Catalysis
JF - ACS Catalysis
SN - 2155-5435
IS - 12
ER -