Highly selective and recyclable hydrogenation of α-pinene catalyzed by ruthenium nanoparticles loaded on amphiphilic core–shell magnetic nanomaterials

Article abstract of DOI:10.1002/aoc.5165

A multifunctional nanomaterial (Fe₃O₄@SiO₂@C_X@NH₂) comprising a magnetic core, a silicon protective interlayer, and an amphiphilic silica shell is successfully prepared. Ru nanoparticles catalyst loaded on Fe₃O₄@SiO₂@C_X@NH₂ is used in hydrogenation of α-pinene for the first time. The novel nanomaterial with amphipathy can be used as a solid foaming agent to increase gas–liquid–solid three-phase contact and accelerate the reaction. Under the mild conditions (40?°C, 1?MPa H₂, 3?h), 99.9% α-pinene conversion and 98.9% cis-pinane selectivity are obtained, which is by far the best results reported. Furthermore, the magnetic nanocomposite catalyst can be easily separated by an external magnet and reused nine times with high selectivity maintaining.

Full text of DOI:10.1002/aoc.5165

Received: 10 May 2019
DOI: 10.1002/aoc.5165
Revised: 9 July 2019
Accepted: 20 July 2019
F U L L P A P E R
Highly selective and recyclable hydrogenation of α‐pinene
catalyzed by ruthenium nanoparticles loaded on
amphiphilic core–shell magnetic nanomaterials
Fang‐Zhu Wu1 | Feng‐Li Yu1 | Bing Yuan1 | Cong‐Xia Xie1,2
| Shi‐Tao Yu3
1 State Key Laboratory Base of Eco‐
A multifunctional nanomaterial (Fe3O4@SiO2@CX@NH2) comprising
a
chemical Engineering, College of
Chemistry and Molecular Engineering,
Qingdao University of Science and
Technology, Qingdao 266042, China
2 Key Laboratory of Biomass Energy and
Material, Jiangsu, Province, Nanjing
210042, China
3 College of Chemical Engineering,
Qingdao University of Science and
Technology, Qingdao 266042, China
magnetic core, silicon protective interlayer, and an amphiphilic
a
silica shell is successfully prepared. Ru nanoparticles catalyst loaded on
Fe3O4@SiO2@CX@NH2 is used in hydrogenation of α‐pinene for the first time.
The novel nanomaterial with amphipathy can be used as a solid foaming agent
to increase gas–liquid–solid three‐phase contact and accelerate the reaction.
Under the mild conditions (40 °C, 1 MPa H2, 3 h), 99.9% α‐pinene conversion
and 98.9% cis‐pinane selectivity are obtained, which is by far the best results
reported. Furthermore, the magnetic nanocomposite catalyst can be easily sep-
arated by an external magnet and reused nine times with high selectivity
maintaining.
Correspondence
Feng‐Li Yu, State Key Laboratory Base of
Eco‐chemical Engineering, College of
Chemistry and Molecular Engineering,
Qingdao University of Science and
Technology, Qingdao, 266042, China.
Email: yufliqust@163.com
KEYWORDS
amphiphilic, core–shell magnetic nanomaterials, hydrogenation, Ru nanoparticles, α‐Pinene
Cong‐Xia Xie, Key Laboratory of Biomass
Energy and Material, Jiangsu, Province,
Nanjing 210042, China.
Email: xiecongxia@126.com
Funding information
Open Project of the Chemistry Depart-
ment in Qingdao University of Science
and Technology of China, Grant/Award
Number: QUSTHX201811; Open Project
of Jiangsu Key Laboratory of Biomass
Energy and Material, Grant/Award Num-
ber: JSBEM201901; Shandong Province
Emphasis Development Plan, Grant/
Award Number: 2017GGX70102; Taishan
Scholar Foundation of Shandong Province
of China, Grant/Award Number:
ts201511033; National Natural Science
Foundation of China, Grant/Award
Number: 31270615
Appl Organometal Chem. 2019;e5165.
wileyonlinelibrary.com/journal/aoc
© 2019 John Wiley & Sons, Ltd.
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https://doi.org/10.1002/aoc.5165

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WU ET AL.
CX@NH2 were used for the first time to catalyze α‐pinene
1 | INTRODUCTION
hydrogenation.
This
novel
nanomaterial
with
In recent years, magnetic nanomaterials have been
widely applied in many important fields such as medicine
control and storage, adsorption stripping, and catalysis,
due to their easy separation, large specific surface area,
interfacial effect, and mesoporous effect.[1–4] Adjusting
the hydrophilicity and hydrophobicity of magnetic mate-
rials is very important for their performance.[5–7]
Undoubtedly, amphiphilic magnetic materials are more
attractive in some applications than hydrophilic or hydro-
phobic congeners. Hence, amphiphilic magnetic
nanomaterials comprising a magnetic inner core and a
amphipathy can be used as a solid foaming agent to
increase the gas–liquid–solid three‐phase contact and
accelerate the reaction.[28] The abundant –NH2 groups
in the outer shell allow the attachment of additional Ru
nanoparticles.[29,30] Furthermore, the magnetic nanocom-
posite catalyst can be easily separated using an external
magnet. Therefore, the novel catalyst Fe3O4@SiO2@‐
CX@NH2/Ru exhibits an excellent catalytic activity, a
high selectivity, and good recyclability in the hydrogena-
tion of α‐pinene under mild conditions, which are by
far the best results reported.
[8,9]
functionalized outer shell are generally prepared
cis‐Pinane is an important industrial intermediate that
is typically applied in medicines, perfumes, and extrac-
tion.[10–12] It is mainly prepared by selective hydrogena-
tion of α‐pinene.[10] Metal nanoparticles exhibit
excellent catalytic activity for the hydrogenation reaction
owing to their quantum size and surface effect.[11,13,14] To
prevent the aggregation of metal nanoparticles, a stabi-
lizer or supported catalyst is usually applied in the cata-
lytic system.[15,16] Touaibia's team has systematically
studied solvent‐free hydrogenation of pinenes over het-
erogeneous catalysts based on different active metals
(Pd, Pt, Ru, and Rh) and supports (carbon, silica and
alumina), and the results show Ru/C provides the best
catalytic activity under 2.75 MPa H2.[17,18] Our research
group has made some progress in the stabilization of
metal nanoparticles by using some polymers such as
2 | RESULTS AND DISCUSSION
Scheme 1 illustrates the overall preparation procedure of
the target catalyst. The magnetic Fe3O4 inner core was
firstly prepared via the redox method, and then wrapped
with an SiO2 layer using the microemulsion method. The
SiO2 layer was mainly used to prevent the corrosion of
Fe3O4 and promote the dispersion of nanoparticles. Sub-
sequently, an alkyl‐modified hydrophobic silica and
NH2‐functionalized hydrophilic silica outer shell were
prepared. Finally, the insitu reduction of an Ru precursor
by NaBH4 produced the target catalyst Fe3O4@SiO2@‐
CX@NH2/Ru.
TEM images of the Fe3O4 core, Fe3O4@SiO2, and
Fe3O4@SiO2@C12@NH2 (Figures S1–S3) clearly show
that the prepared nanoparticles have a uniform spherical
structure, and that the average particle sizes are 51.2,
223.5, and 325 nm, respectively (determined using a
Malvern particle size analyzer) (Figures S4–S6). Particles
between 300 and 350 nm in size account for approxi-
mately 70% of the prepared Fe3O4@SiO2@C12@NH2.
Figure 1 shows the high‐angle annular dark‐field
scanning TEM (STEM) and the corresponding energy‐
dispersive X‐ray spectroscopy (EDX) elemental
mapping images of the target nanocomposite catalyst
Fe3O4@SiO2@C12@NH2/Ru. The STEM‐EDX images
clearly display the distribution of Fe, Si, and Ru elements.
The results confirmed that the magnetic core, silica outer
PVA, F127, P123, and TPGS‐1000 as stabilizers.[19–22]
A
high catalytic activity can be achieved under mild condi-
tions owing to the formation of hydrophobic micellar
microreactors.[23–25] However, the addition of these stabi-
lizers may also lead to the formation of stable emulsions,
resulting in difficulty in catalyst separation from the
product.[26,27]
In this study,
nanomaterial, Fe3O4@SiO2@CX@NH2, comprising
magnetic inner core, SiO2 protective interlayer, and
alkyl‐modifiedhydrophobic and NH2‐functionalized
a
multifunctional magnetic
a
hydrophilic silica outer shell was successfully prepared.
Ru nanoparticles stably loaded on Fe3O4@SiO2@‐
SCHEME 1 Preparation of Fe3O4@SiO2@CX@NH2/Ru catalyst.

WU ET AL.
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FIGURE 1 STEM‐EDX images of
Fe3O4@SiO2@C12@NH2/Ru
shell, and Ru atoms were uniformly immobilized on the
magnetic nanomaterial, thus indicating that Ru existed
in the nanoparticles rather than in the aggregates.
In the FT‐IR spectrum of Fe3O4@SiO2@C12@NH2/Ru
(Figure 2), the absorption peaks of 452 and 1050 cm−1
respectively corresponded to the stretching vibrations of
Fe‐O bond and Si‐O‐Si band, which showed that SiO2
was successfully coated on the magnetic core. The charac-
teristic absorption peaks at 2853 and 2923 cm−1 showed
that the hydrophobic group C12 was successfully intro-
duced in the silica. The broad peak at 3400 cm−1 was
the stretching vibration peak of N‐H bond, indicating that
the hydrophilic functional group ‐NH2 was also grafted
on the silica shell.
The unique hydrophilicity/hydrophobicity of the pre-
pared magnetic nanomaterial was also examined by the
measurement of the water droplet contact angle (Figure
S7). The results indicated that the water droplet contact
angle was approximately 47.5° for Fe3O4@SiO2@‐
C12@NH2/Ru, and but the water droplet contact angle
of Fe3O4@SiO2@C12/Ru was 99.5°, thus revealing the fact
that the NH2‐modified magnetic nanomaterial was
amphiphilic.
FIGURE 2 FT‐IR spectrum of Fe3O4@SiO2@C12@NH2/Ru
The zeta potential of Fe3O4@SiO2@C12@NH2/Ru in
aqueous solution was examined and yielded a value of
+36.7 mV that confirmed a good dispersion stability of
the prepared catalyst in water. However, when applying

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WU ET AL.
an external magnetic field, the catalyst can be well gath-
ered and recovered (Figure 3). Field‐dependent magnetic
characterizations of different nanoparticles were mea-
sured using a magnetic property measurement system
(MPMS) magnetometer at 300 K, and the results showed
that Fe3O4 nanoparticles, Fe3O4@SiO2, and Fe3O4@‐
SiO2@C12@NH2/Ru nanocomposite have magnetization
saturation values of 82.1, 41.5, and 21.12 emu g−1
,
respectively (Figure 4). Although there is a decline of
magnetization saturation value after the progressive mod-
ification of Fe3O4 nanoparticles, an easy separation of the
catalyst from its dispersed aqueous solution within a few
minutes can be achieved by simply using an external
magnet. What's more, the amphiphilic shell can prevent
the irreversible aggregation of magnetic particles after
removal of the magnetic field.
The wide‐angel XRD patterns of various nanomaterials
are shown in Figure 5. A series of diffraction peaks at
2θ = 30.26, 35.68, 43.32, 57.3 and 62.84° are attributed
to Fe3O4 nanoparticles. The diffraction peak near 2θ =
23° is characteristic for amorphous SiO2. For the XRD
pattern of Fe3O4@SiO2@C12@NH2/Ru, it displays the
characteristic diffraction peaks of both the magnetite
phase and the amorphous silica. However, there is no
the characteristic of Ru crystals, indicating that Ru is
highly dispersed and exists in the nanoparticles rather
than in aggregated forms.
FIGURE 4 Magnetic hysteresis loops of nanoparticles recorded
at 25 °C
XPS characterization of Fe3O4@SiO2@C12@NH2/Ru is
afforded. In the full spectrum (Figure S8), the binding
energies of Ru 3P1/2, Ru 3P3/2 and Ru 3d5/2 are located
at 484.5, 462.5 and 280.4 ev, respectively, which is consis-
tent with the standard spectrum of Ru. From the partial
enlargement of Ru 3d, 67.8% of Ru was reduced to
Ru(0) in the zero valence state (Figure S9). The binding
energy changes of the C, O, and N atoms before and after
the loading of Ru nanoparticles were also detected by
XPS. The binding energies of the C and O atoms elicit
FIGURE 5 Wide‐angel XRD patterns of various nanomaterials
FIGURE 3 Dispersion and separation
of Fe3O4@SiO2@C12@NH2/Ru

WU ET AL.
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no any changes (Figures S10 and S11). However,
ΔE = 1.96 eV is observed for the N atoms (Figure S12),
which demonstrates that Ru nanoparticles are mainly
bonded to ‐NH2 on the surface of the nanomaterial.
indicating that amphiphilicity is of great significance
for heterogeneous hydrogenation. Therefore, under
the same conditions, compared with Pd/C and Ru/C
(entries
9
and 10), Fe3O4@SiO2@C12@NH2/Ru
catalyst is used to catalyze the hydrogenation of α‐
• The prepared magnetic nanomaterial catalysts were
used to catalyze the hydrogenation of α‐pinene.
According to the entries 1–3 in Table 1, the modifica-
tion of different carbon chains on Fe3O4@SiO2@‐
Cx@NH2/Ru has a considerable influence on the
catalytic hydrogenation. N2 adsorption–desorption
isotherms in Figure S13 show typical type IV
adsorption–desorption isotherm characteristics with
specific surface areas of 18.19, 31.67, and 53.30 m2/g
for C8, C12 and C18‐modified catalysts, respectively.
The BJH pore size distribution curves in Figures S14
and S15 show that the pore diameters of C18 and
C12‐modified catalysts are up to 7.55 and 3.58 nm,
respectively. However, C8‐modified catalyst has a
non‐uniform pore size distribution (Figure S16),
resulting in a poor loading of Ru nanoparticles.
Another, shorter carbon chain with relatively low
hydrophobicity is not conducive to the dispersion of
the catalyst in the water–organic system. The lager
specific surface area and uniform pore diameter bene-
fit the loading of Ru nanoparticles. However, longer
carbon chains with a larger steric hindrance are
unfavorable to the contacts of the substrate with Ru
nanoparticles. Therefore, C12‐modified catalyst with
optimal amphipathy exhibits the best catalytic activity
(entry 2). By comparison of Pd, Co, and Ni with Ru
nanoparticles (entries 4–6), Ru nanoparticles exhibit
the highest catalytic activity, and can high‐efficiently
convert α‐pinene to cis‐pinane under the mild
pinene with obvious advantages.
For the hydrogenation of α‐pinene catalyzed by
Fe3O4@SiO2@C12@NH2/Ru in the aqueous solution, the
reaction conditions including catalyst dosage, water vol-
ume, H2 pressure, reaction temperature, and the reaction
time, were all optimized (Figsures S17‐21). The results
showed the best hydrogenation conditions were as fol-
lows: a catalyst mass equal to 7 mg, water volume 20
mL, a H2 pressure of 1 MPa, a reaction temperature equal
to 40 °C, and a reaction time of 3 hr. The α‐pinene was
completely converted with a cis‐pinane selectivity of 99%.
Except for the high catalytic activity, another great
advantage of the novel magnetic catalyst is its easy separa-
tion from the reaction system. After the reaction, the mag-
netic catalyst can be easily separated by an external
magnet, and reused to the next reaction. Under the opti-
mum reaction conditions, the recyclability of the magnetic
catalyst for the hydrogenation of α‐pinene is shown in
Figure 6. The conversion and selectivity have no obvious
change during five recycling times. After that, the conver-
sion becomes have a little drop, meanwhile, the high selec-
tivity still maintains. However, when the catalyst is reused
eight times, the conversion of α‐pinene is still higher than
85%. From the TEM of the catalyst after 8th reuse, the
morphology and structure of the catalyst are unchanged.
Compared to the fresh catalyst, the loss of Ru nanoparti-
cles was only 0.15 wt% according to ICP‐AES analysis after
eight cycles, indicating that Ru nanoparticles were stably
loaded on the nanomaterial. Therefore, the decline of
α‐pinene conversion probably owes to the the carbon
deposition in the holes of the molecular sieves.
conditions.
Compared
with
non‐amphiphilic
magnetic materials (entries 7 and 8), magnetic amphi-
philic catalysts have higher catalytic activity,
TABLE 1 Catalytic activity of different modified catalysts[a]
Entry
Catalyst
Conversion/%
Selectivity/%
1
2
Fe3O4@SiO2@C8@NH2/Ru
Fe3O4@SiO2@C12@NH2/Ru
Fe3O4@SiO2@C18@NH2/Ru
Fe3O4@SiO2@C12@NH2/Pd
Fe3O4@SiO2@C12@NH2/Co
Fe3O4@SiO2@C12@NH2/Ni
Fe3O4@SiO2@C12/Ru
Fe3O4@SiO2@NH2/Ru
Pd/C
80.2
99.9
85.2
68.7
32.1
47.5
32.4
52.4
28.3
18.9
98.7
98.9
98.5
84.4
52.7
68.9
98.6
85.4
92.7
31.4
3
4
5
6
7
8
9
10
Ru/C

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WU ET AL.
lower activation energy, and H atoms are more easily
added to the double bond of α‐pinene under the mild
hydrogenation condition. Additionally, the steric hin-
drance of the nanocomposite allows only the endo‐
surface of the α‐pinene to contact with the Ru nanoparti-
cle catalyst, resulting in a high selectivity for cis‐pinane.
In addition to α‐pinene, the novel catalytic hydrogena-
tion system can be applied to many other unsaturated
compounds, including alkenes and aromatic compounds,
as shown in Table 2. Under mild conditions, these
unsaturated compounds can all be very efficiently hydro-
genated. Therefore, the novel catalyst has a wide applica-
tion field.
3 | EXPERIMENTAL
FIGURE 6 Recyclability of the catalyst (40 °C, 1 MPa, 3 hr)
3.1 | Chemicals and reagents
As Figure 7, the microscopic image of H2 bubbles in
the oil–water biphasic interface for the novel catalytic
system clearly showed that the bubbles gradually
migrated into the oil phase from the water phase, became
small and gradually broke. The released hydrogen then
reacted with α‐pinene in the oil phase on the surface of
the solid catalyst. The catalytic reaction proceeded at
the gas–liquid–solid interface. The novel amphipathy
nanomaterial can be used as a solid foaming agent to
increase gas–liquid–solid three‐phase contact and further
accelerate the reaction. What's more, every nanocompos-
ite is equivalent to a microreactor. Therefore, for the
novel catalytic system, the hydrogenation reaction has a
Hexadecyl trimethyl ammonium bromide (CTAB), octyl
trimethoxysilane (C8), dodecyl trimethoxysilane (C12), 3‐
aminopropyl trimethoxysilane (APTS), and hydrated
ruthenium trichloride (RuCl3·3H2O) were purchased
from the Aladdin Industrial Corporation. Hydrated ferric
trichloride (FeCl3·6H2O), trisodium citrate, sodium ace-
tate, ethylene glycol, octadecyl trimethoxysilane (C18),
tetraethylsilane (TEOS), tetramethylsilane (TMOS), aque-
ous ammonia (NH3·H2O, 28 wt%), sodium hydroxide
(NaOH), and sodium borohydride (NaBH4) were obtained
from Shanghai Macklin Biochemical Technology Co.,
TABLE 2 Hydrogenation of unsaturated compounds using the
new catalytic system
P/
T/ t/
Substrate
Product
MPa °C min Conversion/%
1
35 60
99.89
1
1
1
1
35 60
30 40
35 60
35 60
99.98
99.95
99.95
99.96
1
25 40
99.97
1
1
1
25 40
25 40
30 40
99.99
99.97
99.98
FIGURE 7 Microscopic image of H2 bubbles in oil–water
biphasic interface

WU ET AL.
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LTD. Additionally, α‐pinene (98%) was supplied by
Guangxi Wuzhou Rosin Factory, and hydrogen
(99.99 wt%) was obtained from Qingdao Airichem
Specialty Gases & Chemicals Co., Ltd. All solvents were
purchased and purified before use. Doubly deionized
water was used in all experiments.
magnet and washed to be neutral with water and ethyl
alcohol. The solid powder was then extracted with anhy-
drous ethanol 3 times to remove organic template agent
CTAB at 80 °C for 12 hr every time. The formed
precipitate was separated and desiccated to afford amphi-
philic core‐shell structured Fe3O4@SiO2@C8@NH2.
Fe3O4@SiO2@C12@NH2 and Fe3O4@SiO2@C18@NH2
were prepared according to the same procedure, when
octyl trimethoxysilane (C8) was replaced by dodecyl
trimethoxysilane (C12) and octadecyl trimethoxysilane
(C18) respectively, meanwhile the dosage of TEOS in the
previous step respectively was changed to 400 mg and
800 mg.
3.2 | Synthesis of Fe3O4 nanoparticles
The magnetic nanoparticles were synthesized through a
solvothermal reaction according to the literature.[31] The
reaction system was isolated from moisture throughout
the entire preparation process. FeCl3·6H2O (0.65 g) and
trisodium citrate (0.26 g) were rapidly mixed and
completely dissolved into ethylene glycol (20 ml),
followed by the addition of sodium acetate (1.20 g). A
homogeneous dark suspension was gotten after continu-
ously stirring for 30 min, and then transferred into a
teflon‐lined autoclave and maintained at 200 °C for
10 hr. Cooled to ambient temperature, the black Fe3O4
nanoparticles were obtained after ethanol and water
washing subsequently, and final vacuum drying.
3.5 | Loading of Ru nanoparticles
Ruthenium nanoparticles were loaded on the prepared
Fe3O4@SiO2@Cx@NH2 by impregnation method.
Fe3O4@SiO2@CX@NH2 (0.20 g) was first dispersed in
20 ml of ethyl alcohol, and RuCl3·3H2O (0.20 g) was
added. The mixture was placed for 30 mins under ultra-
sonic. After that, NaBH4 (10 ml, 1 mol L−1) was slowly
added into the above mixture under vigorous stirring.
After stirring 4 hr at 40 °C, the black precipitate was col-
lected by using a magnet, washed by ethyl alcohol, and
dried under vacuum. The magnetic nanocomposite cata-
lyst Fe3O4@SiO2@CX@NH2/Ru was afforded.
3.3 | Synthesis of core‐shell structured
Fe3O4@SiO2
For the silica coating, Fe3O4 nanoparticles (400 mg) were
first dispersed in a mixture of ethanol (60 ml) and deion-
ized water (40 mL) by ultrasonication, and then aqueous
ammonia solution (2 ml, 28 wt%) and TEOS (100 mg)
were added sequentially. The mixture was stirred for
8 hr at room temperature to form a SiO2 coating layer
through condensation on the magnetic nanoparticles.
The obtained core‐shell Fe3O4@SiO2 nanoparticles were
collected by using a magnet and washed several times
with deionized water and ethanol.
3.6 | Hydrogenation of α‐pinene
In a typical reaction, α‐pinene (1.0 g), the catalyst
Fe3O4@SiO2@CX@NH2/Ru (20 mg), and 20 ml of H2O
were added into a 100 ml of high pressure reaction kettle.
After sealing the kettle, the atmosphere in the kettle was
replaced by 4 MPa H2 4 times, and 1 MPa H2 was finally
filled. The mixture was stirred for 3 hr at 40 °C. After the
reaction, the kettle was cooled to room temperature. The
catalyst Fe3O4@SiO2@CX@NH2/Ru was recovered by
using a magnet and reused. The product was collected
by extraction with n‐heptane, and analyzed by gas chro-
matography (GC).
3.4 | Synthesis of amphiphilic core‐shell
structured Fe3O4@ SiO2@CX@NH2
In a typical synthesis, the core‐shell Fe3O4@SiO2 nano-
particles (250 mg) were dispersed in a solution of deion-
ized water (100 ml) and methanol (125 ml), and 625 μL
of NaOH solution (1 mol L−1) and CTAB (0.88 g) were
added. The mixture was vigorously stirred at room tem-
perature for 2 hr. 162 μL of octyl trimethoxysilane (C8)
was added into the above mixture and stirred for 1 hr.
Then 358 μL of TMOS and 322 μL of APTS were dropwise
added into the above solution. After that, the solution
was further stirred for 12 hr and crystallized for another
12 hr. The white solid was obtained by an external
3.7 | Measurements and characterization
The morphology of amphiphilic magnetic nanomaterial
was determined with a JEOL JSM‐6010LV scanning elec-
tron microscope (SEM) and a JEOL JEM‐2100 transmis-
sion electron microscope (TEM). The high‐angle,
annular dark field scanning TEM (STEM), and the corre-
sponding energy dispersive X‐ray (EDX) elemental map-
ping images were recorded on TALOS F200X high

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WU ET AL.
resolution TEM. FT‐IR spectra were obtained using a
Nicolet 510P FT‐IR spectrometer with the KBr method
(frequency range from 4000 to 400 cm−1). The zeta poten-
tial was examined by a Nano S90 Malvern particle size
analyzer. The water droplet contact angle was quantified
by a JC2000 contact angle meter. XRD measurements
were performed on a Rigaku D/max‐2400 diffractometer
when Cu‐Ka anode radiation was used as the X‐ray
source at 40 kV and 100 mA in the 2θ range of 0–80.
The content of Ru was determined by using ICP‐AES
method which was running at 1200 W. Before the analy-
sis, the catalyst was dissolved in a mixture of hydrofluoric
acid and aqua regia. XPS data were recorded by using
mono Al‐Ka as X‐ray source and the hydrocarbon peak
ACKNOWLEDGMENTS
The authors are very grateful for the financial supports
from the National Natural Science Foundation of China
(31270615), the Taishan Scholar Foundation of Shandong
Province of China (ts201511033), the Shandong Province
Emphasis Development Plan (2017GGX70102), the Open
Project of Jiangsu Key Laboratory of Biomass Energy and
Material (JSBEM201901), and the Open Project of the
Chemistry Department in Qingdao University of Science
and Technology of China (QUSTHX201811).
ORCID
Cong‐Xia Xie https://orcid.org/0000-0002-1209-2745
of C at 284.60 eV was used to calibrate binding ener-
1s
gies. The porous structure of the catalyst was measured
by a Micromeritics ASAP 2020 N2 adsorption–desorption
isotherm at 77 K. Brunauer–Emmett–Teller (BET) surface
areas were calculated from the linear part of the BET plot.
Pore size distribution was estimated from the adsorption
branch of the isotherm by the BJH method. The magnetic
hysteresis loop of the catalyst was recorded by a MPMS3
magnetism performance measurement. Leica SP8 laser
scanning confocal microscopy was used to study H2 bub-
ble images in the hydrogenation reaction. The hydroge-
REFERENCES
[1] Y. J. Ai, Z. N. Hu, Z. X. Shao, L. Qi, Nano Res. 2018, 11, 287.
[2] A. Maryam, K. Nadiya, K. Eskandar, Appl. Organomet. Chem.
2018, 32, 4346.
[3] R. Liu, Y. L. Guo, G. Odusote, F. L. Qu, ACS Appl. Mater. 2013,
5, 9167.
[4] H. H. Zai, Y. Z. Zhao, S. Y. Chen, L. Ge, Nano Res. 2018, 11,
2544.
[5] Q. Zhang, X. Z. Shu, J. M. Lucas, F. D. Toste, G. A. Somorjai, A.
nation product was analyzed by
a GC‐9790 gas
P. Alivisatos, Nano Lett. 2013, 14, 379.
chromatography instrument with a FID detector.
[6] M. S. Islam, W. S. Choi, S. H. Kim, O. H. Han, H. J. Lee, Adv.
Funct. Mater. 2015, 25, 6061.
[7] H. B. Zou, R. W. Wang, Z. Q. Shi, J. Y. Dai, Z. T. Zhang, S. L.
Qiu, J. Mater. Chem. A 2016, 4, 4145.
4 | CONCLUSION
[8] B. K. Kaang, N. Han, W. Jang, H. Y. Koo, Chem. Eng. J. 2018,
331, 290.
Highly dispersed and stable catalysts comprising Ru
nanoparticles supported on magnetic amphiphilic core‐
shell nanomaterial (Fe3O4@SiO2@CX@NH2/Ru) are suc-
cessfully prepared for use in hydrogenation of α‐pinene
for the first time. The abundant ‐NH2 in the outer shell
allows attaching more Ru nanoparticles. The novel
nanomaterial with amphipathy can be used as a solid
foaming agent to increase gas–liquid–solid three‐phase
contact and accelerate the reaction, and every nanocom-
posite is equivalent to a microreactor. Furthermore, the
magnetic nanomaterial can be easily separated by an
external magnet and efficiently reused. Therefore, the
novel catalyst of Fe3O4@SiO2@CX@NH2/Ru exhibits an
excellent catalytic activity, high selectivity, and good
recyclability in the hydrogenation of α‐pinene under the
mild conditions. More importantly, except for α‐pinene,
the novel catalytic hydrogenation system can be applied
to many others alkenes and aromatic compounds. The
development of the novel magnetic amphiphilic
nanomaterial is of great significance, and it shows a good
application prospect.
[9] M. Esmaeilpour, S. Zahmatkesh, N. Fahimi, M. Nosratabadi,
Appl. Organomet. Chem. 2018, 32, 4302.
[10] N. Li, Q. F. Ma, W. Liu, Y. H. Lv, Fine Chem. 2010, 11, 1073.
[11] S. B. Ren, J. H. Qiu, C. Y. Wang, B. L. Xu, Y. N. Fan, Y. Cen,
Chin. J. Inorg. Chem. 2007, 6, 1021.
[12] E. Y. Varón, A. Selka, A. S. Fabiano‐Tixier, M. Balcells, R. C.
Garayoa, A. Bily, M. Touaibia, F. Chemat, Green Chem. 2016,
18, 6596.
[13] S. Tanielyan, N. Biunno, R. Bhagat, R. Augustine, Top. Catal.
2014, 57, 1564.
[14] V. A. Semikolenov, I. lyna, I. L. Simakova, Appl. Catal. A 2001,
211, 91.
[15] I. L. Simakova, Y. Solkina, I. Deliy, J. Warna, D. Y. Murzin,
Appl. Catal. A 2009, 356, 216.
[16] M. L. Casella, G. F. Santori, A. Moglioni, V. Vetere, J. F.
Ruggera, G. M. Iglesias, O. A. Ferretti, Appl. Catal. A 2007,
318, 1.
[17] A. Selka, N. A. Levesque, D. Foucher, O. Clarisse, F. Chemat,
M. Touaibia, Org. Process Res. Dev. 2017, 21, 60.
[18] F. J. N. Moutombi, A. Selka, A. S. F. Tixier, D. Foucher, O.
Clarisse, F. Chemat, M. Touaibia, C. R. Chim. 2018, 21, 1035.

WU ET AL.
9 of 9
[19] Y. H. He, S. Hwang, D. A. Cullen, M. A. Uddin, Energy Environ.
Sci. 2019, 12, 250.
[29] Y. Liu, L. Li, S. W. Liu, C. X. Xie, J. Mol. Catal. A‐Chem. 2016,
424, 269.
[30] H. Veisi, S. B. Hemmati, P. Safarimehr, J. Catal. 2018, 365, 204.
[20] M. Zhao, C. H. Deng, X. M. Zhang, Chem. Commun. 2014, 47,
1359.
[31] S. R. Kandibanda, N. Gundeboina, S. Das, V. M. Sunkara,
J. Photochem. Photobiol. B 2018, 178, 270.
[21] S. L. Hou, X. Y. Wang, C. R. Huang, C. X. Xie, S. T. Yu, Catal.
Lett. 2016, 146, 1.
SUPPORTING INFORMATION
[22] S. L. Hou, C. X. Xie, F. L. Yu, B. Yuan, S. T. Yu, RSC Adv. 2016,
6, 54806.
Additional supporting information may be found online
in the Supporting Information section at the end of the
article.
[23] S. L. Hou, C. X. Xie, H. Zhong, S. T. Yu, RSC Adv. 2015, 5,
89552.
[24] X. Y. Wang, F. L. Yu, C. X. Xie, S. T. Yu, Mol. Catal. 2018, 444,
62.
[25] X. Y. Feng, X. Y. Wang, D. Zhang, F. Feng, Small 2018, 14,
1703570.
How to cite this article: Wu F‐Z, Yu F‐L, Yuan
B, Xie C‐X, Yu S‐T. Highly selective and recyclable
hydrogenation of α‐pinene catalyzed by ruthenium
nanoparticles loaded on amphiphilic core–shell
magnetic nanomaterials. Appl Organometal Chem.
2019;e5165. https://doi.org/10.1002/aoc.5165
[26] L. H. Xie, X. Y. Wang, F. L. Yu, B. Yuan, RSC Adv. 2017, 7,
51452.
[27] J. Y. Dai, H. B. Zou, R. W. Wang, Y. Wang, Green Chem. 2017,
19, 1336.
[28] Y. Zhang, Q. Yue, L. Liu, X. Y. Yang, Adv. Mater. 2018, 30,
1800345.