ACS Catalysis
Letter
Recycling tests verified that the current catalyst maintained high
activity for five consecutive runs without decrease in the
selectivity of 1-octanal (more than 99%). The slight decrease in
1
-octanol conversion was assigned to the minor aggregation of
copper nanoparticles (Supporting Information, Figure S7).
On the basis of these findings, we conclude that Cu
nanoparticles selectively dispersed on the {110} facets of
La O CO nanorods are highly active for transfer dehydrogen-
2
2
3
ation of primary aliphatic alcohols. The medium-strength basic
sites on the {110} facets of the rod-shaped La O CO
3
2
2
interacted strongly with Cu nanoparticles, generating a
catalytically active nanoenvironment for the reaction coupling
between alcohol dehydrogenation and styrene hydrogenation.
This strategy raises the prospect of using nanostructured solid
catalysts for the efficient dehydrogenation of alcohols to
functionalized carbonyls, and consequently contributes to the
sustainable development of green chemistry.
ASSOCIATED CONTENT
■
*
S
Supporting Information
Materials and methods; additional experimental results in the
structural analyses of the catalysts, dehydrogenations of
different types of alcohols, reaction kinetics, and recycle tests.
Figure 2. Possible reaction pathway of 1-octanol transfer dehydrogen-
AUTHOR INFORMATION
■
ation. (a) Profiles of temperature-programmed desorptions of CO on
2
the La O CO nanorods (black curve) and the Cu/La O CO catalyst
2
2
3
2
2
3
(
red curve); the intense desorption peaks at about 560 K represented
3+
2−
the medium-strength basic sites (La -O pairs) with a total amount
of 0.16 mmol·g on the La O CO nanorods and 0.11 mmol·g on
the Cu/La O CO catalyst. (b) Hexagonal unit of La O CO crystal
−1
−1
2
2
3
Notes
2
2
3
2
2
3
The authors declare no competing financial interest.
(
left) in which the C and O atomic sites are 1/3 occupied at the arrow-
indicated sublayers (the gray ball refers as to the vacancies), and the
atomic arrangements (right) of the {001} and {110} planes. (c) IR
spectra of 1-octanol adsorption on bare La O CO nanorods (black
ACKNOWLEDGMENTS
■
2
2
3
This work was supported by the National Natural Science
Foundation of China (20923001, 21025312) and the National
Basic Research Program of China (2010CB631006,
2013CB933100).
curve) and the Cu/La O CO (red curve) at 423 K. (d) A depicting
2
2
3
scheme of 1-octanol dehydrogenation on the Cu nanoparticle and the
{
110} plane of the La O CO . (e) Arrhenius plot of the reaction rate
2
2
3
on the Cu/La O CO catalyst at 373−423 K. (f) TOFs as a function
2
2
3
of copper particle size at 423 K.
REFERENCES
■
Kinetic measurements identified that the activation energy
for the transfer dehydrogenation of 1-octanol was 75 kJ mol−1
on the Cu/La O CO catalyst in the temperature range of
(1) Hudlicky, M. Oxidations in organic chemistry; American Chemical
Society: Washington, DC, 1990.
(
2) (a) Mallat, T.; Baiker, A. Chem. Rev. 2004, 104, 3037.
2
2
3
(
b) Matsumoto, T.; Uneo, M.; Wang, N.; Kobayashi, S. Chem.
3
73−423 K, which is very similar to that of the previous Cu/
Asian J. 2008, 3, 196. (c) Prabhakaran, V. C.; Lee, W. K.; Adam, F. J.
Chem. Technol. Biotechnol. 2011, 86, 161.
La O catalyst (Supporting Information, Figure S6). However,
2
3
the reaction rate on the Cu/La O CO catalyst was much
2
2
3
(
3) (a) Abad, A.; Concepcion, P.; Corma, A.; Garcia, H. Angew.
higher than that on the Cu/La O catalyst; it increased from
2
3
Chem., Int. Ed. 2005, 44, 4066. (b) Su, F. Z.; Liu, Y. M.; Wang, L. C.;
Cao, Y.; He, H. Y.; Fan, K. N. Angew Chem., Int. Ed. 2008, 47, 334.
.17 × 10− mol g
8
−1 −1
s
at 373 K to 8.33 × 10 mol g
23 K (Figure 2e and Supporting Information, Table S2),
−7
−1 −1
s
at
4
4
́
(c) Boronat, M.; Corma, A.; Illas, F.; Radilla, J.; Rodenas, T.; Sabater,
probably because of the high density of basic sites on the
La O CO nanorods (Supporting Information, Figure S6). The
M. J. J. Catal. 2011, 278, 50. (d) Costa, V. V.; Estrada, M.; Demidova,
Y.; Prosvirin, I.; Kriventsov, V.; Costa, R. F.; Fuentes, S.; Simakov, A.;
Gusevskaya, E. V. J. Catal. 2012, 292, 148.
2
2
3
reaction rate also strongly depended on the size of the Cu
particles involved in hydrogen transfer and styrene hydro-
genation. When increasing the size from 3.8 to 5.6 nm, the
turnover frequency (TOF) decreased dramatically from 3.97×
(4) (a) Mori, K.; Hara, T.; Mizugaki, T.; Ebitani, K.; Kaneda, K. J.
Am. Chem. Soc. 2004, 126, 10657. (b) Meenakshisundaram, S.; Ewa,
N.; Ramchandra, T. Chem.Eur. J. 2011, 17, 6524.
(
5) Yamada, Y. M. A.; Arakawa, T.; Hocke, H.; Uozumi, Y. Angew
−
3
−1
−3 −1
10
s
to 1.10 × 10
s
at 423 K, but further increasing the
Chem., Int. Ed. 2007, 46, 704.
6) (a) Hayashi, M.; Yamada, K.; Nakayama, S.; Hayashi, H.;
size of copper particle to 9.2 nm only moderately lowered the
TOF to 7.41 × 10
Table S3). Control experiments confirmed the heterogeneous
(
−
4 −1
s
(Figure 2f and Supporting Information,
Yamazaki, S. Green Chem. 2000, 2, 257. (b) Keresszegi, C.; Mallat, T.;
Baiker, A. New J. Chem. 2001, 25, 1163. (c) Tanaka, T.; Kawabata, H.;
Hayashi, M. Tetrahedron Lett. 2005, 46, 4989.
nature of the reaction (Supporting Information, Table S4).
8
93
dx.doi.org/10.1021/cs400255r | ACS Catal. 2013, 3, 890−894