10.1002/cctc.201601246
ChemCatChem
with excellent catalytic activity exhibiting 93% conversion of
propylene oxide and 94% selectivity for 1-methoxy-2-propanol.
These results suggested that the low-temperature preparation
strategy might be employed as an effective approach to generate
basic sites on the mesoporous silica for diverse base-catalyzed
reactions.
distribution of the catalyst was studied by Temperature Programmed
Desorption of CO2 (CO2-TPD) using a BELSORP BEL-CAT-A apparatus.
o
The samples were activated at 350 C for 1 h prior to the adsorption of
CO2 at room temperature. After the physical adsorbed CO2 was purged by
a He flow (99.999%) at room temperature, the samples were heated to
850 oC at the rate of 10 oC·min−1, and the CO2 liberated was detected by
an Omni Star mass spectrometer.
Experimental Section
Catalyst test and analysis
The obtained basic materials were also applied to catalyze the synthesis
of 1-methoxy-2-propanol via the addition reaction of propylene oxide and
methanol. The typical process was carried out in a 50ml sealed autoclave
with mole ratio of methanol and propylene oxide being 5:1. After running
at 393K for 5 h under magnetic stirring, the reactor was cooled down to
room temperature. The products were analyzed by a gas chromatograph
with a flame ionization detector after vacuum filtering to separate from the
catalyst.
Catalyst preparation
The SBA-15 sample was synthesized by using the hydrothermal method
as follows: Typically, 2.0 g of triblock copolymer P123 was dissolved in 75
g of 1.6 M HCl aqueous solution with stirring at 40 oC, followed by the
addition of 4.25 g of TEOS. The mixture was stirred at 40 oC for 24 h, and
then was hold in static state at 100oC for 24 h. The precipitate was filtrated,
washed with deionized water, dried and calcined at 550 oC for 5 h with the
heating ramp of 2 oC·min−1 in a muffle burner. Thus, the mesoporous SBA-
15 material was obtained. [29]
The La2O3-SBA-15 sample was prepared according to the following
procedure: 1.10 g of La(NO3)3·6H2O was dissolved in ethanol followed by
adding 1.0 g of SBA-15 sample. After keeping stirred for 12 h at 50 oC, the
ethanol in the mixture was recycled at 50 oC with stirring. The formed
precipitate was dried in vacuum at 60 oC overnight, and then finally
calcined at 560 oC in still air for 5 h with the heating ramp of 2 oC·min−1 in
Acknowledgments
We gratefully acknowledge the support of this research by the
National Natural Science Foundation of China (No. 21676229,
21276217), the China Postdoctoral Science Foundation(No.
2014M552143), the Innovation Platform Open Funds of Hunan
Provincial Education Department (No. 15K125, 16K086), the
Research Foundation of Education Bureau of Hunan Province
(No. 13C912) and the Graduate Innovation Fund of Hunan
province (No. CX2013B276).
The typical process for KF supported on La2O3-SBA-15 by the post-
synthesis method: A required amount of anhydrous alkaline species KF
SBA-15. After stirred at room temperature for 4 h, the mixture was heated
to 45 oC to remove methanol with stirring in a polytetrafluoroethylene
beaker and the white power was dried under vacuum at 60oC for 12 h and
subsequently calcined at 350oC for 3 h with the heating ramp of 2oC·min−1
in a muffle furnace. The obtained samples were denoted as x%KF/La2O3-
SBA-15, where x is the mass ratio of KF to La2O3 -SBA-15. By directly
introducing KF into the SBA-15 as the above-mentioned method, the
sample of KF/SBA-15 was obtained.
Keywords: superbases·mesostructure •SBA-15· lanthanum
Oxide·potassium fluoride
[1]
a) A. M. Frey, S. K. Karmee, K. P. de Jong, J. H. Bitter, U. Hanefeld,
ChemCatChem 2013, 5, 594-600; b) Y. Wang, L. Wang, C. Liu, R. Wang,
ChemCatChem 2015, 7, 1559- 1565; c) L. Sun, X. Liu Q, H. Zhou, Chem.
Soc. Rev. 2015, 44, 5092-5147; d) A. M. Frey, J. H. Bitter, K. P. de Jong,
ChemCatChem 2011, 3, 1193-1199.
Catalyst characterization
[2]
a) J. Xie, L. Chen, C. T. Au, S. Yin. Catal. Commun. 2015, 66, 30-33; b)
J. Zhao, J. Xie, C. T. Au, S. Yin. RSC Adv. 2014, 4, 6159-6164; c) C. Sun,
F. Qiu, D. Yang, B. Ye, Fuel Process. Technol. 2014, 126, 383-391; d) J.
Zhao, J. Xie, C. T. Au, S. Yin. Appl. Catal. A 2013, 467, 33-37; e) S. Zhang,
S. Yin, Y. Wei, S. Luo, C. T. Au. Catal. Lett. 2012, 142, 608-614. f) Y. Ding,
H. Sun, J. Duan, P. Chen, H. Lou, Catal. Commun. 2011, 12, 606-610.
a) N. Pasupulety, K. Gunda, Y. Liu, G. L. Rempel, F. T. T. Ng, Appl. Catal.
A 2013, 452, 189-202; b) L. Chen, J. Zhao, S. Yin, C. T. Au, RSC Adv.
2013, 3, 3799-3814; c) R. Song, D. Tong, J. Tang, C. Hu, Energ. Fuel.
2011, 25, 2679-2686; d) P. Unnikrishnan and D. Srinivas, Ind. Eng. Chem.
Res. 2012, 51, 6356-6363.
X-ray diffraction (XRD) patterns of the samples were recorded using a
Bruker D8 Advance diffractometer with monochromatic Cu Kα radiation in
the 2θ ranges from 0.7°to 5°and 10°to 80°, respectively, at 40 kV and
30 mA. The average crystallite size was calculated from the (111)
diffraction peak using Scherrer’s equation. High-resolution transmission
electron microscopy (HRTEM) experiment was conducted on a JEM-2010
UHR electron microscope operated at 200 kV. The morphology and
components of the materials were characterized using a Zeiss Ultra 55
type scanning electron Microscope (SEM) equipped with an Oxford X-Max
type energy dispersive spectroscopy (EDS). N2 adsorption-desorption
[3]
[4]
a) E. M. Johansson, M. A. Ballem, J. M. Córdoba, M. Odén, Langmuir
2011, 27, 4994-4999; b) R. Zubrzycki, J. D. Epping, T. Ressler,
ChemCatChem 2015, 7, 1112-1121.
o
experiments were carried out using a Belsorp II system at -196 C. The
temperature of the degasification was 150 oC and the degasification time
was 3 h. The multipoint Brunauer-Emmet-Teller (BET) surface areas were
calculated over the relative pressure range from 0 to 1.0. Fourier transform
infrared (IR) measurements were carried out on a Nicolet Nexus 470
spectrometer with a spectra resolution of 2 cm−1 using transparent KBr
pellets. The base strength (H−) of the catalyst was detected by using a
series of Hammett indicators, and the total surface basicity of the catalysts
was studied by acid-basic titration.[30] The basicity and the basic strength
[5]
[6]
A. M. Frey, T. van Haasterecht, K. P de Jong, J. H. Bitter, ChemCatChem
2013, 5, 3621-3628.
a) Z. Wu, Q. Jiang, Y. Wang, H. Wang, L. Sun, L. Shi, J. Xu, Y. Wang, Y.
Chun, J. Zhu, Chem. Mater. 2006, 184, 4600 -4608; b) L. Sun, Y. Sun, X.
Liu, L. Zhu, X. Liu, Curr. Org. Chem. 2014, 18, 1296-1304; c) Y. Sun, L.
Sun, T. Li, X. Liu, J. Phys. Chem. C 2010, 114, 18988-18995.
a) X. Liu, L. Sun, F. Lu, X. Liu, X. Liu, Chem. Commun. 2013, 49, 8087-
8089; b) X. Liu, L. Sun, X. Liu, A. Li, F. Lu, X. Liu, ACS Appl. Mater. Inter.
2013, 5, 9823-9829;
[7]
6
This article is protected by copyright. All rights reserved.