Journal of the American Chemical Society
Article
icals), TiO (Degussa P25), CeO (Rhodia HAS-10), SiO (Aeroxide
0.2 mL/min) was introduced into the system with the HPLC pump.
The liquid samples were separated from the effluents by the 16-port
sampling loop, collected in 16 vials, and finally analyzed by GC−MS.
Analysis Method. Liquid products were analyzed by a Shimadzu
2010 GC−MS equipped with a HP-5 capillary column (30 m, 0.32
mm inner diameter, 0.25 μm film). Internal standard (i.e., eicosane)
was used for quantification. Both injection and detection temperatures
are 320 °C. The temperature program is set in the following way: from
60 to 80 °C (rate: 2 °C/min), then increase to 300 °C (rate: 10 °C/
min) and hold for 15 min. Note that by using a high injection port
temperature, e.g., 320 °C, reliable and direct quantification for fatty
acids can be achieved without chemical derivitization. The vapor phase
was analyzed online by a gas chromatograph with TCD detector and
two capillary columns (MS-5A and HP-Plot Q).
2
2
2
Alu C-Degussa), and Al O (Aeroxide Alu C-Degussa). Microalgae oil
2
3
was provided by Verfahrenstechnik Schwedt GmbH.
Catalyst Preparation. Ni supported on ZrO , TiO , CeO , SiO ,
2
2
2
2
and Al O were synthesized by the wetness impregnation method. The
2
3
ZrO support was prepared from zirconium hydroxide by calcination
2
in air at 400 °C for 4 h. For example, the procedure for preparing 10
wt % Ni/ZrO follows: Ni(NO ) ·6H O (5.83 g) was dissolved in
2
3
2
2
water (10 g), and then such solution was slowly dropped onto ZrO2
10 g) with continuous stirring. After metal incorporation with support
(
at ambient temperature for 4 h, the catalyst was first dried overnight at
ambient temperature and then dried at 110 °C for 12 h. Afterward, the
catalyst was calcined in synthetic air at 400 °C for 4 h (flow rate = 100
mL/min) and reduced at 500 °C for 4 h (ramp = 2 °C/min) in
hydrogen (flow rate = 100 mL/min).
Catalyst Characterization. Atomic Absorption Spectroscopy
ASSOCIATED CONTENT
Supporting Information
Catalyst characterization, impact of reaction temperature on
stearic acid conversion, turnover frequency (TOF) for stearic
acid conversion with different catalysts, microalgae oil
■
(
AAS). The metal loading was determined by atomic absorption
*
S
spectroscopy using a UNICAM 939 AA-spectrometer. Prior to
measurement, the sample was dissolved in a mixture of hydrofluoric
acid (48%) and nitro-hydrochloric acid at the boiling point of the
mixture (about 110 °C).
BET Specific Surface Area. The BET specific surface area was
determined by nitrogen adsorption−desorption at −196 °C using the
Sorptomatic 1990 series instrument. The sample was activated in
vacuum at 300 °C for 2 h before measurement.
AUTHOR INFORMATION
Temperature-Programmed Desorption (TPD). Temperature-pro-
grammed desorption of ammonia or carbon dioxide was performed in
a 6-fold parallel reactor system. The catalysts were activated in He at
5
00 °C (5 °C/min ramp) for 1 h. NH and CO were adsorbed with
3 2
Notes
partial pressures of 1 mbar at 100 or 35 °C, respectively. Subsequently,
the samples were purged with 30 mL/min He for 2 h in order to
remove physisorbed molecules. For the temperature-programmed
desorption experiments, six samples were sequentially heated from 100
to 765 °C with an increment of 10 °C/min to desorb ammonia and
from 35 to 450 °C to desorb carbon dioxide. The rates of desorbing
species were monitored by mass spectrometry (Balzers QME 200).
For the quantification of amount of acidity, a standard HZSM-5 zeolite
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
We appreciate the partial financial support from EADS
Deutschland GmbH. The work is also partially supported by
Technische Universitat Munchen in the framework of Euro-
̈
̈
pean Graduate School for Sustainable Energy.
■
(
Si/Al = 45) with known acid site concentration was used to calibrate
the signal. The response of the CO signal was calibrated using the
decomposition of NaHCO3.
2
REFERENCES
■
X-ray Powder Diffraction (XRD). The structures of the metal
oxides-supported Ni catalysts were analyzed by X-ray diffraction using
a Philips X’Pert Pro System. The radiation source was Cu Kα
operating at 40 kV/45 mA. The sample was measured with a scan rate
of 1 deg/min from 5° to 70° (2θ). The metal particle size was
calculated from diffraction by te Scherrer equation. The XRD patterns
of the prepared Ni-based catalysts are displayed in Figure S1 [SI].
Experimental Procedure for Reaction in the Autoclave. The
typical experiments with microalgae oil, stearic acid, or 1-octadecanol
were carried out as follows: reactant (1.0 g), dodecane (100 mL), and
catalyst (0.5 g) were loaded into the batch autoclave (Parr Instrument,
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3
00 mL). Then the autoclave was purged with N2 at ambient
(8) Sotelo-Boyas
2011, 50, 2791.
(9) Huber, G. W.; O’Connor, P.; Corma, A. Appl. Catal., A 2007,
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temperature, and until the required temperature was achieved, it was
pressurized by H . The reaction was carried out at 260 °C in presence
of 40 bar H (reaction temperature) at a stirring speed of 600 rpm for
2
2
8
h. The products in the vapor phase were analyzed by the online gas
chromatograph (GC), while the liquid samples were manually
collected during the run and later analyzed by GC−MS.
Conversion = (weight of converted reactant/weight of the starting
reactant) × 100%. Yield (C%) = (C atoms in each product/C atoms in
the starting reactant) × 100%. Yield (wt %) = (weight of each
product/weight of the starting reactant) × 100%.
Experimental Procedure for Reaction in the Continuous
Flow Reactor. The continuous flow reaction system with a trickle bed
reactor used for the catalyst stability and deactivation test is
schematically shown in Figure S4 [SI]. The stainless steel tubular
reactor (1/4 in. o.d.) was loaded with 0.5 g catalyst with a particle size
2000, 60, 83.
(11) Laurent, E.; Delmon, B. J. Catal. 1994, 146, 281.
(12) Peng, B.; Yao, Y.; Zhao, C.; Lercher, J. A. Angew. Chem., Int. Ed.
2012, 51, 2072.
(13) The equations below display the hydrodeoxygenation,
decarbonylation, and decarboxylation pathways for alkane production
using fatty acid as reactant. As fatty acid can be used as a representative
reactant, similar equations can be written for triglycerides conversion.
Hydrodeoxygenation: R−COOH + 3H → R−CH + 2H O
2
3
2
(1)
(2)
between 150 and 280 μm. After the reduction of the catalysts in H at
2
Decarbonylation: R−COOH + H → R−H + CO + H O
4
50 °C for 2 h, the system was kept at 270 °C and pressurized with H2
2
2
to 40 bar. A liquid solution of microalgae oil in dodecane (1.33 wt %,
9
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dx.doi.org/10.1021/ja302436q | J. Am. Chem. Soc. 2012, 134, 9400−9405