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The desired amount of RuCl3ꢁ3H2O (0.13 g; 0.5 mmol of Ru for
5 wt% Ru/MgO) in methanol (10 mL), and NaBH4 (0.38 g, 10 mmol)
in methanol (20 mL), were placed in the two dropping funnels,
respectively. While the MgO suspension was being stirred at room
temperature, 10 mL of the NaBH4 solution was added to the flask,
after which both RuCl3 and NaBH4 solutions were simultaneously
added into the mixture at the same rate of about one drop per
second. After addition was complete, the dropping funnels were re-
moved and the mixture was stirred under N2 at room temperature
overnight. At the end, the solution was colorless and the solid was
gray or dark. The solid was filtered off, washed with methanol
(10 mL) six or more times until no Clꢀ could be detected in the fil-
trate by use of AgNO3 aqueous solution. The catalyst was dried un-
der vacuum at room temperature, affording a fine gray to black
powder, depending on the metal loading.
The powdered samples were mounted on studs in air using a dou-
ble-sided adhesive tape. Spectra recording was controlled by the
EIS software (V. 2.2.4), using a scan step of ꢀ0.5 eV for survey scans
and ꢀ0.1 eV for narrow scans. The binding energy scale was cor-
rected for charging effect according to the position of Mg 2s photo-
electron line (88.1 eV) [82,94]. The asymmetrical XPS peaks were
deconvoluted by the curve fitting approach by use of XPSPEAK
4.1, applying Shirley background subtraction and Lorentzian-
Gaussian functions (20% L, 80% G).
4.3.5. N2 Physisorption, H2 pulse chemisorption and CO2-TPD
measurements
The BET surface area of support, the Ru surface area and CO2
temperature-programmed desorption measurements were all con-
ducted in a dual station Micromeritics Chemisorb 2750 analyzer
fitted with a ChemiSoft TPx System. See Supporting Information
for detailed experimental procedures.
4.3. Catalyst characterization
4.3.1. TEM studies
4.4. Catalytic tests
Transmission electron micrographs were obtained on a JEOL
JEM-2010 microscope operating at an accelerating voltage of
200 kV with a point-to-point resolution of 0.19 nm and magnifica-
tion up to 1,500,000ꢃ. Images were captured digitally using an
AMT Advantage CCD camera system (HRB Bottom Mount DVC
Camera, 1 Megapixel) controlled by the AMT Image Capture Engine
Software (Version 600.163) at varied high magnifications. The lin-
ear measurements on images had been calibrated previously at dif-
ferent high magnifications using known lattice spacing of
crocidolite crystals standard (d = 0.906 nm) and graphited carbon
crystals standard (d = 0.34 nm). TEM samples were prepared by
placing a drop of catalyst suspension in THF on a holey carbon film
coated copper grid and allowing evaporation of the solvent in the
air. The particle size (Feret diameter) distribution histogram was
constructed from the measurement of about 300 particles found
in representative images. The normal size distribution curve was
also obtained based on the mean value and the standard deviation
of the particle size.
Hydrogenation experiments were carried out using a 5513 Parr
reactor (100 mL) fitted with an internal stirrer and a dip tube, a
thermocouple, a sampling valve and a high-pressure buret, coupled
to a 4836 controller. Reactions were performed in a glass liner
placed inside the vessel of the reactor. In a typical hydrogenation
run at 120 °C and 10 atm, the reactor was loaded with the desired
amount of catalyst and 20 mL of THF and then sealed. Hydrogen
was introduced into the reactor through the high-pressure buret
and released through the releasing valve; this was repeated three
times in order to deoxygenate the system, after which the reactor
was re-pressurized to 6 atm and heated to 120 °C to reach
ꢄ10 atm. After the catalyst was incubated at 120 °C and 10 atm
for 1 h, 10 mL of substrate solution in THF was placed into the
high-pressure buret, which was subsequently charged with
10 atm of H2. The reactor was depressurized to about 2–3 atm
and the substrate solution in the buret was then quickly injected
into the reactor; this was taken as the zero time of the reaction.
The pressure was kept constant at 10 atm by feeding H2 through
an open connection to the hydrogen tank. Samples of the reaction
mixtures were periodically withdrawn from the reactor and ana-
lyzed immediately by use of a Varian 3900 gas chromatograph fit-
ted with a polar Supelco SP-2330 capillary column and a Saturn
2100T mass detector. The identity of each product was verified
through comparison of its mass spectrum with the instrument’s li-
brary and the molar percentage of each product was calculated
based on peak areas and relative response factors previously deter-
mined by using standard solutions containing known amounts of
each component. When necessary, samples were analyzed in a Shi-
madzu 2010 gas chromatographer fitted with a Restek Rtx-5 or
Supelco SE-30 capillary column and an FID detector. Anthracene
and sulfur compounds were added into the reactor together with
catalyst from the beginning without catalyst incubation. Each
experiment was repeated at least twice in order to ensure repro-
ducibility; the variations in the calculated TOF values for repeat
experiments were typically within 5%.
4.3.2. Powder XRD measurements
Powder X-ray diffraction patterns were recorded on a Philips
X’PERT MPD diffractometer using monochromatic Cu Ka radiation
(k = 1.5406 Å) at 45 kV and 40 mA. Sample powder was placed in
the holder with a flat surface and analyzed in air at room temper-
ature. Spectra data were collected at a scanning rate of 0.10°/s in a
step size of 0.050° for 2h over the range from 10° to 75° using the
X’Pert Data Collector software (V. 2.2f). Phase identification was
achieved by comparing the diffraction patterns of sample with that
of ICDD (JCPDS) standards within the X’Pert HighScore software (V.
2.2c).
4.3.3. EDX analysis
The elemental composition of catalyst was assessed by energy-
dispersive X-ray spectroscopy using a Zeiss Supra 55VP field emis-
sion scanning electron microscope equipped with an EDX detector.
The samples were dispersed onto carbon tape and sputter coated
with carbon before analysis. The spectra were acquired using the
EDAX Genesis software, with an operating voltage at 15 kV and a
working distance of 8.5 nm.
4.5. Recycling experiments and catalyst life time determination
About 100 mg of 10 wt% catalyst and 50 mL of neat toluene
were placed in a glass liner inside the vessel of the reactor. The sys-
tem was deoxygenated by flushing with H2 three times. The reac-
tor was first kept under 1 atm H2 and then heated to 120 °C; after
the temperature became stable, the reactor was pressurized to
10 atm, and this was taken as the zero time for the reaction. The
pressure was kept constant during the whole reaction course.
Samples were periodically withdrawn and the composition was
4.3.4. XPS analysis
X-ray photoelectron spectroscopy analysis was performed with
an Omicron XPS spectrometer equipped with an EA125 multichan-
nel hemispherical energy analyzer and a dual Al/Mg X-ray source
using the monochromatic Al Ka radiation (1486.6 eV). The binding
energy scale was previously calibrated and the base pressure in the
ultra-high-vacuum analysis chamber was around 2.0 ꢃ 10ꢀ9 torr.