A Selective Functionalized Mesoporous Silica-Supported Rh Catalyst for Effective 1-Octene Hydroformylation
Jeon et al.
solvent was then drawn off through a syringe under N2
and the resulting solid washed three times with hexane.
The solid powder (brown in color) was vacuum dried at
ambient temperature (henceforth designated MCM-41/
AEAPMDMS/Rh).
functionalized mesoporous silica MCM-41 was dried at
100 C for 12 h.
ꢀ
For the purposes of Rh immobilization, the same process
was performed. The detailed conditions were as follows:
2.5 g of MCM-41/Ph Si(OEt) /AEAPMDMS, 0.0925 g of
2
3
2
2
Rh (CO) in hexane, 5 h stirring at room temperature
4
12
under N (henceforth designated MCM-41/Ph Si(OEt) /
AEAPMDMS/Rh).
2
.3. Synthesis of Mesoporous Materials by the
Selective Functionalization Method—Method 2
2
2
2
The sample of mesoporous silica MCM-41 was achieved
by a general process and the surfactant template left unre-
moved (without calcinations). As-synthesized (filled with
template) MCM-41 (2.04 g) was dispersed in a mixture of
isopropanol and 12.0 N HCl (70:70 = g:g). Then, 3.26 g
2
.5. 1-Octene Hydroformylation
Hydroformylation of 1-octene was performed according
to a previous method. The prepared catalyst, internal
and external (or selectively internal) rhodium-immobilized
aminated mesoporous materials, was added to a SUS-316
autoclave reactor containing 75 mL of THF and 4.68 g of
1-octene. Then, 0.044 g (or 0.022 g) of TPP was added to
the mixture as the ligand. Subsequently, the autoclave was
flushed with N . The syn-gas (CO/H = 1) in the reactor
of trimethylchlorosilane (TMCS) was added and stirred at
ꢀ
8
0 C for 2 h. After 2 h, the isolated solid was washed
with methanol, a mixture of methanol/deionized water and
deionized water until the chloride was not detected. In
order to remove the template, 1.5 g of the dried powder
product was added to the ethanol and n-heptane mixture
2
2
was pressurized up to 300 psi and depressurized to atmo-
spheric pressure three times. After the reactor was heated
(
50 wt%) with 0.58 g of hydrochloric acid. The system
ꢀ
ꢀ
was refluxed at 70 C for approximately two days (external
grafting).
to 140 C, the syn-gas was introduced to bring the total
pressure to 300 psi. The system was maintained at 140 C
ꢀ
To graft the internal surface, 1.0 g of TMCS was dis-
persed in 75 mL of toluene and stirred at 50 C for
.5 h. Afterwards, 0.007 g of p-toluenesulfonic acid and
for 0.5 h and the syn-gas filled from a reservoir in order to
maintain a pressure of 300 psi. The homogeneous rhodium
catalyst was also used for 1-octene hydroformylation for
comparison with the heterogeneous system. The rhodium
acetate dimer, as the homogeneous Rh catalyst, was diluted
with methanol. Then the calculated mixture was added to
the reaction system. All experimental steps were identical
to those described above and are listed in Table III. Final
products were analyzed by gas chromatography (GC).
ꢀ
0
2
.0 mmol of AEAPMDMS were added to the system and
Delivered by Ingenta to: Nanyang Technological University
ꢀ
the mixture refluxed at 120 C for 2 h. The material was
IP: 46.161.56.57 On: Sun, 05 Jun 2016 06:48:13
filtered, washed with ethanol three times, and dried at
Copyright: American Scientific Publishers
ꢀ
1
00 C for 12 h.
The Rh complex was then immobilized on the internal
surface of the mesoporous materials using the same proce-
dure whereby 1.1 g of MCM-41/TMCS/AEAPMDMS was
immersed in hexane and 0.037 g of Rh (CO) in hexane
4
12
2.6. Characterizations
was added. The mixture was then stirred for 5 h under
ambient temperature. Finally, the hexane was removed,
washed with hexane three times, and dried under vacuum
Nitrogen adsorption–desorption isotherms were obtained
ꢀ
using a Micrometrics ASAP 2020 at −196 C. Prior to
ꢀ
ꢀ
analysis, the samples were degassed at 350 C (or 200 C)
for 3 h. The surface area was calculated according to the
Brunauer–Emmett–Teller (BET) equation and the pore vol-
ume obtained from the t-plot method. Small-angle pow-
der X-ray diffraction (XRD) patterns were recorded on
a Rigaku D/max-2500 X-ray diffractometer. The sam-
(designated MCM-41/TMCS/AEAPMDMS/Rh).
2
.4. Synthesis of Mesoporous Materials by the
Selective Functionalization Method—Method 3
Mesoporous silica MCM-41 was prepared according to the
above method and then calcined. The as-calcined MCM-41
ꢀ
ꢀ
ples were scanned from 0.3 to 5.0 (2ꢄꢃ with a step
ꢀ
(
3.0 g) was then dispersed in 80 mL of toluene and stirred
size of 0.01 at 300 mA and 40 kV. Transmission elec-
ꢀ
at 50 C for 0.5 h. After sufficient immersion, 0.021 g of
tron microscopy (TEM) was carried out on a Tecnai
G2 F30 (FEI company) operated at an acceleration volt-
age of 300 kV. The nitrogen and carbon contents of the
rhodium-immobilized materials were determined by ele-
mental analysis (EA) using a Flash EA 1112 series (CE
Instruments). The amount of the anchored rhodium on
the materials was calculated by an inductively coupled
plasma-atomic emission spectrometer (ICP-AES) using an
Optima 4300DV (PERKIN ELMER) after HF treatment.
The 1-octene hydroformylation products were analyzed
using a GC-2014 (Shimadzu).
p-toluenesulfonic acid and 6.0 mmol of Ph Si(OEt) were
2
2
ꢀ
added sequentially and the mixture stirred at 120 C for
2
h. The isolated solid product was washed with ethanol
ꢀ
three times and dried at 100 C for 12 h (external grafting).
For the internal grafting process, 3.0 g of MCM-
4
1/Ph Si(OEt) was added to 80 mL of toluene. After 0.5 h
2 2
ꢀ
of stirring at 50 C, 0.021 g of p-toluenesulfonic acid and
6
.0 mmol of AEAPMDMS were added and the mixture
ꢀ
refluxed at 120 C for 2 h. The solid product was filtered
and washed with ethanol three times. Then, the selective
3
090
J. Nanosci. Nanotechnol. 13, 3087–3095, 2013