ChemCatChem
10.1002/cctc.201700312
FULL PAPER
[
17b]
temperature for 2 h.
The synthesized catalysts were labelled as Ni
2
P-
were kept in sealed vials and subsequently analyzed by gas
chromatography (Shimadzu GC-14B), with a flame ionization detector
and a capillary column, CP Wax 52 CB. The furfural conversion,
selectivity and yield were calculated and defined as follows:
x-y, where x represents the weight percentage of nickel in catalysts and y
the initial P/Ni molar ratio.
Powder X-ray diffraction (XRD) patterns were obtained in
a PAN
analytical X´Pert Pro automated diffractometer, in Bragg-Brentano
reflection configuration, by using a Ge (111) primary monochromator (Cu
mol of furfural converted
Conversion ꢀ%ꢁ =
Selectivity ꢀ%ꢁ =
× 100
× 100
mol of furfural fed
α
K 1) and the X´Celerator detector with a step size of 0.017º (2θ),
-1
between 10 and 70º in 2θ with an equivalent counting time of 712 s step .
mol of the product
The crystallite size (D) was calculated by using the Williamson-Hall
mol of furfural converted
[
23]
equation, B cos θ = (K λ / D) + (2 ε sin θ), where θ is the Bragg angle,
B is the full width at half maximum (FWHM) of the XRD peaks, K is the
Scherrer constant, λ is the wavelength of the X ray and ε the lattice strain.
Conversion × Selectivity
Yield % =
ꢀ ꢁ
1
00
CO chemisorption analyses were performed under static volumetric
conditions using a Micromeritics ASAP 2020 apparatus. Samples were
reduced ex situ and then transferred to an inert atmosphere. Prior to
Acknowledgements
2
measurement, samples were reduced in situ in H at 400 °C and
evacuated at 25 °C for 10h. The chemisorption isoth erms were obtained
by measuring the amount of CO adsorbed between 10 and 600 mmHg at
The authors are grateful to financial support from the Spanish
Ministry of Economy and Competitiveness (CTQ2015-64226-C3-
35 °C . After completing the initial analysis, the r eversibly adsorbed gas
3-R project), Junta de Andalucía (P12-RNM-1565) and FEDER
was evacuated and the analysis was repeated to determine only the
chemisorbed amounts.
(
European Union) funds.
Keywords: furfural; 2-methylfuran; biomass; nickel phosphide;
The textural parameters were evaluated from nitrogen adsorption–
desorption isotherms at -196 ºC, as determined by an automatic ASAP
hydrogenation
2
020 Micromeritics apparatus. Prior to measurements, samples were
-4
outgassed at 200 ºC and 10 mbar overnight. Specific surface areas
BET) were determined by using the Brunauer–Emmett–Teller (BET)
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wool. Prior to the catalytic test, catalysts were reduced in situ under a H
2
-1
flow (60 mL min ) at 550ºC for 1 h in the case of nickel-based catalyst
and 620 ºC for the nickel phosphide-based catalysts. After reduction,
catalysts were cooled down to the selected reaction temperature under a
-1
2
H flow (10-60 mL min ). After reaching this temperature, a flow of 3.87
-1
mL h of a furfural solution in cyclopentyl methyl ether (CPME) (5 vol%)
was continuously injected by means of a Gilson 307SC piston pump
(
model 10SC). The furfural was dissolved in CPME in order to avoid
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as blockage of the lines due to the polymerization of furfural. CPME is an
environmentally friendly solvent that has been used in different organic
reactions, thus demonstrating to be a green co-solvent for the selective
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[
36]
dehydration of lignocellulosic pentoses to furfural. The liquid samples
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