K. Liu et al.
oxidation of benzyl alcohol. The valence of Pd and oxi-
dation mechanism are also discussed, and the mechanism is
testified by catalytic and characterization results.
S
S
S
S
S
S
SBA-15SS
SBA-15SCCS
SBA-15SCCCS
2
Experimental
S
S
S
S
S
S
2
.1 Materials and Methods
Pd
Pd(OAc)
2
Pd(OAc)
2
(
OAc)
2
SBA-15 was synthesized according to Zhao’s method [12],
which was calcinated at 300 °C for 3 h before used. Pal-
SBA-15SSPd(OAc)
2
SBA-15SCCSPd(OAc)
2
SBA-15SCCCSPd(OAc)
2
ladium acetate (Pd (OAc) ), benzyl alcohol and benzyl
SBA-15
2
aldehyde were obtained from Sinopharm Chemical
Reagent Co. Ltd. 1,3-propanedithiol and 1,2-ethanedithiol
were obtained from Darui chemical reagent Co. Ltd. Tri-
ethoxyvinylsiliane and (3-mercaptopropyl) triethoxysilane
were supplied by Energy Chemical Co. Ltd.
Scheme 1 The structures of SBA-15SS, SBA-15SCCS, SBA-
5SCCCS, SBA-15SSPd, SBA-15SCCSPd and SBA-15SCCCSPd
1
To triethoxyvinylsilane 6.7 mL was added 1,3-dimeca-
ptopropane (2 mL) or 1,2- dimecaptoethane (2 mL) and di-
tert-butyl peroxide (two drops) [14]. The mixture was
stirred at room temperature for 1 h, the product was
evaporated under reduced pressure, which were designated
as SCCS or SCCCS.
X-ray diffraction patterns (XRD) of the catalysts were
performed on a Bruker D8 diffractometer with Cu Ka
o
o
radiation from 0.5 to 90 with a scan speed 1 /min. X-ray
photoelectron spectroscopy (XPS) measurements were
obtained on a PHI-5500 spectrometer with Al Ka X-ray
radiation as the X-ray source for excitation. Transmitting
electron microscopy (TEM) was performed on a JEOL
1
1
H NMR (300 MHz, CDCl ) SCCS: H NMR (300 MHz,
3
CDCl ): d 3.81 (dd, J = 7.2, 6.9 Hz, 12H), d 2.73–2.67 (m,
3
4H), d 2.65–2.61 (m, 4H), d 1.20 (t, J = 8.4 Hz, 18H), d 0.96
2100F instrument operating at 30 kV. N2 adsorption–
desorption isotherms were measured with a BEL SORP mini
(
t, J = 3.6 Hz, 4H).
1
1
H NMR (300 MHz, CDCl ) SCCCS: H NMR
3
II analyzer at liquid N temperature. Surface area (SBET) was
2
(
300 MHz, CDCl ): d 3.83 (dd, J = 6.9, 7.2 Hz, 12H), d
3
calculated by the BET method, the pore volume (V ) was
p
2
.66–2.64 (m, 4H), d 2.62–2.59 (m, 4H), d 1.82–1.89 (m,
H), d 1.22 (t, J = 6.6 Hz, 18H), d 1.00 (t, J = 8.7 Hz, 4H).
determined by nitrogen adsorption at a relative pressure of
2
0
.98, and average pore size (D) was determined from the
desorption isotherms using the Barrett–Joyner–Halenda
BJH) method. Inductively coupled plasma atomic emission
2.2.2 Preparation of SS, SCCS and SCCCS Coated SBA-15
(
spectroscopy (ICP-AES) measurements were performed on
the Thermo Scientific iCAP 6300 instrument. CO chemi-
sorption was performed on Autochem 2910 instrument.
The sulfur coated SBA-15 was prepared according to
protocols in the literature [14]. SBA-15 1 g was dispersed
in dry toluene (dried by sodium), after SS, SCCS or
SCCCS added the system was heated to 120 °C under
argon atmosphere for 12 h. After the reaction, the resultant
was washed with toluene at least five times to remove the
unreacted SS, SCCS or SCCCS, and then the product was
dried at 60 °C in vacuum for 12 h. The product was
abbreviated as SBA-15SS, SBA-15SCCS, and SBA-
2
.2 Synthesis of the Catalysts
2
.2.1 Synthesis of SS, SCCS and SCCCS
Bis(triethoxysilylpropyl)disulfide was prepared using
MnO as catalyst. MnO was synthesized in accordance
2
2
15SCCCS for short.
with according to the literature [13]. 3.2 g MnO2 was
added to the 100 mL bottle. Thereafter, 5 g 3-mercapto-
propyl triethoxysilane was added quickly. The solution was
vigorously stirred and 5 mL chloroform was added. The
reaction system was stirred for 1 h. The organic phase was
filtered, which was evaporated to obtain of product as
2.2.3 Preparation of Supported Pd Catalysts
To a solution of Pd(OAc) (0.32 g, 1.4 mmol) in dichlo-
2
romethane (20 mL) was added SBA-15SS, SBA-15SCCS,
SBA-15SCCCS (2 g). The mixture was stirred at room
temperature for 24 h and then filtered, washed with
dichloromethane until the filtrate was colorless. The orange
product was then dried under reduced pressure for one
night, which was labeled as SBA-15SSPd. (The structures
colorless oil. The product was abbreviated as SS for short.
1
H NMR (300 MHz, CDCl ): d 3.83 (dd, J = 6.9,
3
6
.9 Hz, 12H), d 2.70 (t, J = 7.2 Hz, 4H), d 1.80 (t,
J = 7.5 Hz, 4H), d 1.22 (t, J = 6.6 Hz, 18H), d 0.73 (t,
J = 8.7 Hz, 4H),
1
23