Bifunctionalized Hollow Nanospheres
(
P123), BTME, DA, MO, and DIBK were purchased from Sigma–Al-
acetone (2.0 g), n-nonane (0.50 g, internal GC standard), and cata-
lyst (0.20 g). Before reaction, the autoclave was purged three times
with H , then pressurized with H and placed in an oil bath, which
À1
drich. Amberlite 120 with a dry acidity of 4.4 mmolg was pur-
chased from Alfa Aesar. The resins were heated under vacuum at
2
2
1
208C before use to remove adsorbed water. PdCl with a Pd con-
was preheated to the reaction temperature, and was stirred with
a speed of 800 rpm. Judging from the resulting pressure, most of
the acetone remained liquid under such conditions. After reaction,
the autoclave was cooled in an ice bath at 08C, depressurized in
a gas bag with a stopcock to collect gaseous products (propene
and propane), and opened. The reaction mixture was then re-
moved from the autoclave and the products were separated from
the catalyst by centrifugation. The liquid products were identified
by comparison with the standard substance and quantified by GC
analysis, using an Agilent Technologies 6890 instrument equipped
with a flame ionization detector and a 30 mꢁ0.25 mm poly(ethy-
lene glycol) (PEG) capillary column (Dalian Elite Co.). To recycle the
solid catalyst, the catalyst was filtered from the reaction system,
thoroughly washed with ethanol, dried for 5 h at 808C, and directly
used in the next cycle. Regeneration of the catalysts was accom-
plished by stirring the used catalysts in aqueous H SO (0.5m).
2
tent of 59 wt% was used as the metal precursor. Other reagents
were obtained from Shanghai Chemical Reagent Inc. (Chinese Med-
icine Group).
Syntheses
SO H-functionalized ethane–silica hollow nanospheres (nSO H-E-
HS): The material was synthesized according to a modified method
developed by us. In a typical synthesis, F127 (0.80 g) and sodium
acetate (1.38 g, 16.80 mmol) were dissolved in deionized water
3
3
[9]
(
28 mL) at 208C under vigorous stirring. After dissolution of the co-
polymer, the mixture of BTME and MPTMS was added under stir-
ring. The molar composition of the mixture was Si/F127/NaOAc/
H O=100:0.63:168:15560. The resultant mixture was stirred at
2
2
4
2
08C for 24 h and aged at 1008C under static conditions for 24 h.
The solid product was recovered by filtration and air-dried at room
temperature overnight. Finally, the surfactant was extracted by
heating a solution of the as-synthesized material (1.0 g) in ethanol
(
200 mL) and concentrated aqueous HCl (1.5 g) at reflux for 24 h.
After extraction of the surfactant, the resulting solid (1.0 g) was dis-
persed in H O (30 wt% in aqueous solution, 40 g). The resultant
Characterization
2
2
mixture was stirred for 12 h at 258C. After filtration, the solid mate-
rial was stirred in H SO (200 mL, 0.1m) for 12 h at room tempera-
ture for acidification. After thoroughly washing with deionized
The nitrogen sorption experiments were performed at À1968C
using a Micrometrics ASAP 2020 accelerated surface area and po-
rosimetry analyzer. Samples were degassed at 1208C for 5 h prior
to the measurements. BET specific surface areas were calculated
2
4
water, the solid product was dried at 608C overnight. The sample
was denoted as nSO H-E-HS (ethylene group in the network),
using adsorption data at the relative pressure (P/P ) range of 0.05–
3
0
where n (n=10, 20, 30, 40) was the mol% ratio of MPTMS/
0.25. Pore-size distributions were derived from the adsorption
branch by using the BJH method. The total pore volumes were es-
(
BTME+MPTMS) in the initial mixture. The acid exchange capacities
of nSO H-E-HS were determined by acid–base titration.
timated from the amounts adsorbed at P/P =0.99. TEM analyses
3
0
were performed using a FEI Tecnai G2 Spirit transmission electron
microscope at an acceleration voltage of 120 kV. Before examina-
tion, the samples were dispersed in anhydrous ethanol and depos-
ited on a holey carbon film on a Cu grid. FTIR spectra were collect-
ed with a Nicolet Nexus 470 IR spectrometer (KBr pellets were pre-
pared) in the range of 400–4000 cm . Solid state diffuse reflec-
tance UV/Vis spectra for powder samples were recorded by using
a Shimadzu UV-2550 UV/Vis spectrophotometer equipped with an
SO H-functionalized silica hollow nanospheres (SO H-Si-HS): The
3
3
material was synthesized according to a modified method previ-
[10]
ously developed by us using a mixture of TMOS and MPTMS as
the silane sources [the MPTMS/(TMOS+MPTMS) mol% ratio was
2
0%]. This sample was denoted as SO H-Si-HS (network composed
3
À1
of pure silica).
SO H functionalized SBA-15 (SO H-SBA-15) and FDU-12 (SO H-FDU-
3
3
3
1
2): The materials were synthesized according to a modified
integrating sphere by using BaSO as a white standard. S elemental
4
[11]
method previously developed by us using a mixture of tetraethyl
orthosilicate (TEOS) and MPTMS as the silane sources [the MPTMS/
analyses were determined by means of an Elementar Vario EL III
13
29
analyzer. CPMAS C (100.6 MHz) and MAS Si NMR (79.5 MHz) ex-
periments were recorded by using a Bruker DRX-400 spectrometer
(
TEOS+MPTMS) mol% ratio was 20%]. The samples had 2D meso-
channels and a cage-like porous structure and were denoted as
SO H-SBA-15 and SO H-FDU-12, respectively.
equipped with a magic-angle spin probe in a 4 mm ZrO rotor
using tetramethylsilane as reference. For CPMAS C NMR experi-
2
13
3
3
ments the parameters used were: 8 kHz spin rate, 3 s pulse delay,
Immobilization of Pd onto SO H-functionalized materials: The Pd-
3
29
4
min contact time, and 1000 scans; for MAS Si NMR experiments
doped catalysts were prepared by impregnation. SO H-functional-
3
the parameters used were: 8 kHz spin rate, 3 s pulse delay, 10 min
contact time, and 1000 scans. SEM was undertaken by using a FEI
Quanta 200F scanning electron microscope operating at an accel-
erating voltage of 1–30 kV. Powder X-ray diffraction (PXRD) data
were collected on a Rigaku D/Max-2500PC diffractometer with
CuKa radiation (l=1.5418 ꢂ) over the 2q range of 5–708 with
ized materials were mixed with an aqueous solution of PdCl2
(
0.02m) acidified with a few drops of HCl (2.0m), followed by sol-
vent evaporation in a rotary evaporator and subsequent washing
+
À
with water to remove residual H and Cl ions. The reduction of
II
0
À1
Pd to Pd was accomplished in a hydrogen flow (30 mLmin ) at
2
1
008C for 2 h. The Pd-loaded nSO H-E-HS, SO H-Si-HS, SO H-SBA-
3 3 3
À1
a scan speed of 58min at room temperature. The adsorption of
5, and SO H-FDU-12 were denoted as Pd/nSO H-E-HS, Pd/SO H-Si-
3
3
3
water and acetone vapors was measured at 208C on a Micrometrics
ASAP 2020 instrument after the samples were degassed for 6 h at
HS, Pd/SO H-SBA-15, and Pd/SO H-FDU-12, respectively. Their con-
3
3
tent in Pd was 1.0 wt%.
8
08C. The ultrapure water used in vapor adsorption experiments
General process for the one-pot synthesis of MIBK catalyzed by the
solid catalyst: The one-pot synthesis of MIBK was carried out in
a 20 mL stainless steel autoclave equipped with a pressure gauge
and a magnetic stirrer. Typically, the autoclave was charged with
was produced by using a freeze–pump–thaw technology for three
cycles. Acetone (AR grade) was first washed with a dilute KMnO4
solution and then distilled with anhydrous Na SO , followed by
2
4
three cycles of freeze–pump–thaw.
ChemSusChem 2012, 5, 2390 – 2396
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2395