Catalysis Science & Technology
Page 2 of 7
ARTICLE
DOI: 10.1039J/oCu4CrnY0a0l2N50aDme
(XPS), thermogravimetric analysis (TGA), scanning electron catalysts was examined by transmission electron microscopy
microscopy (SEM), transmission electron microscopy (TEM), (TEM, JEOL JEMꢀ2100F).
inductively coupled plasmaꢀatomic emission spectrometer
(ICPꢀAES), Xꢀray diffraction (XRD), N2 sorption. The
performances of the catalyst for catalyzing HDO of phenolic
compounds were examined, and the effects of the reaction
temperature and time on phenol HDO reaction were
investigated. The possible reaction pathway was discussed as
well.
Hydrodeoxygenation of phenolic compounds to cyclohexanes.
The HDO reactions of phenolic compounds were performed
in a 15 mL stainless steel autoclave equipped with a magnetic
stirrer. In a typical experiment for HDO of phenol, phenol (2
mmol), catalyst (40 mg), and water (3 mL) were loaded into the
reactor. After being purged with H2 three times to remove the
air inside, the autoclave was then charged with H2 up to 5 MPa
at room temperature. The autoclave was heated at the desired
Experimental section
temperature (e.g., 200°C) with stirring at 1000 rpm. After a
Materials
suitable reaction time, the reactor was moved to iceꢀwater to
quench the reaction, and ethylbenzene was added as an internal
standard. The organic phase was extracted from the reaction
mixture by ethyl acetate three times, and analyzed by an
Agilent 6890 gas chromatograph equipped with an HPꢀ
INNOWax capillary column and an FID detector.
Unless otherwise stated, all chemicals in this work were
commercial available and used without further purification.
Chemicals include: phenol (Sinopharm, >99% GC assay),
hydroquinone (Alfa Aesar, >99% GC assay), diphenyl ether
(Alfa Aesar, >99% GC assay), 4ꢀnꢀpropylphenol (TCI, >99%
GC assay), guaiacol (J&K, >98% GC assay), cyclohexanol
(Alfa Aesar, >99% GC assay), cyclohexanone (Alfa Aesar, >99%
GC assay), nꢀpropylcyclohexane (TCI, >99% GC assay), 4ꢀnꢀ
propylcyclohexanone (TCI, >99% GC assay), 4ꢀnꢀ
Results and discussion
Characterization for the catalysts
propylcyclohexanol (TCI, >99% GC assay),
hydrogen
(Beijing Analytical Instrument Company, >99.99%). Na+ꢀMMT
(Zhejiang Sanding Co., Ltd ), RuCl3 (Aladdin), 1ꢀsulfobutylꢀ3ꢀ
methylimidazolium hydrosulfate (ILꢀSO3H, Lanzhou Institute
of Chemical Physics, Chinese Academy of Sciences).
In this work, a Brøsted acidic, ILꢀSO3H, as shown in
Scheme 1, was used to modify MMT and assist the
immobilization of Ru particles onto the MMT support. In the
process to prepare Ru/MMT@ILꢀSO3H, MMT was first treated
in the ILꢀSO3H aqueous solution to immobilize this IL onto the
MMT support via ionꢀexchange and/or adsorption; then the ILꢀ
treated MMT served as the support to be decorated with Ru
particles, resulting in Ru/MMT@ILꢀSO3H. The asꢀprepared
Ru/MMT@ILꢀSO3Hcatalyst was first examined by different
techniques.
Procedures for the synthesis of catalyst
The Ru/MMT@ILꢀSO3H catalyst was prepared based on the
procedures reported previously.24 Typically, 3.0 g of Na+ꢀMMT
was dispersed in 100 mL of aqueous solution of ILꢀSO3H (3.0g)
under sonication to form a stable suspension, and stirred at
90°C for 24 h. Subsequently, the treated MMT was separated
via centrifugation and washing with distilled water for abundant
times to remove the unabsorbed IL, finally washed with ethanol.
Scheme 1.Brønsted acidic IL.
Then this slurry was dried at 70°C in vacuum overnight,
followed by being grinded to powders, which was denoted as
MMT@ILꢀSO3H. The resultant MMT@ILꢀSO3H was
redispersed in the RuCl3aqueous solution, and stirred at room
temperature for12 h. The slurry was centrifugated and washed
Figure 1 showed the IR spectra of MMT, ILꢀSO3H and
Ru/MMT@ILꢀSO3H. The existence of the band around 1630
cmꢀ1 in the IR spectrum of Ru/MMT@ILꢀSO3H was assigned to
CꢀNꢀC or CꢀC bonds, originated from ILꢀSO3H, indicating the
presence of ILꢀSO3H in the catalyst.
with distilled water for five times, which was then dried at 70
°C
in vacuum overnight, followed by hydrogenation at 200 C for 3
°
h, resulting in Ru/MMT@ILꢀSO3H. The loading content of
Ruin Ru/MMT@ ILꢀSO3H was 0.46wt% determined by ICPꢀ
AES. For comparison, Ru/MMT was prepared via dispersing
MMT in the RuCl3 aqueous solution to adsorb Ru3+ onto the
MMT support, followed by hydrogenation at 200 °C.
Catalyst characterization
Powder Xꢀray diffraction (XRD) patterns were recorded on a
Rigaku D/maxꢀ2500 Xꢀray diffractometer using CuKα radiation
(λ= 0.15406 nm) with voltage at 40 kV and current at 200 mA.
The Xꢀray photoelectron spectroscopy (XPS) data were
obtained with an ESCALab 220iꢀXL electron spectrometer
from VG Scientific using 300W AlKα radiation. The base
pressure was about 3×10ꢀ9 mbar. The binding energies were
referenced to the C1s line at 284.6 eV from adventitious carbon.
The specific surface areas of the samples were determined by
N2 sorption technique on TriStar II 3020. The samples were
Figure 1 FTꢀIR spectra of MMT, ILꢀSO3H and Ru/MMT@ILꢀSO3H.
The TG analysis was performed in the temperature range
from room temperature to 1000°C in air, and the weight loss vs
temperature plot is illustrated in Figure 2. It is obvious that
there were two weight losses in each TGA curve for MMT and
degassed at 200 °C for 3 h, and the adsorption–desorption
isotherms were measured at 77 K. The morphology of the
2 | Catal. Sci. Technol., 2014, 00, 1-6
This journal is © The Royal Society of Chemistry 2012
Xu, Huanjun
