Chemoselective flow hydrogenation of Α,Β – Unsaturated aldehyde with nano-nickel

Article abstract of DOI:10.1016/j.catcom.2017.04.048

Herein, it is presented a novel catalytic system for the continuous-flow chemoselective hydrogenation of α,β – unsaturated aldehydes used in the production of high-value cosmetics and pharmaceuticals precursors. The reaction was catalyzed by nano-nickel particles grafted on polymeric support, synthesized via a simple, adaptable and green methodology. The system was highly active and very selective to C[dbnd]C bond saturation.

Full text of DOI:10.1016/j.catcom.2017.04.048

Accepted Manuscript
Chemoselective flow hydrogenation of α,β – Unsaturated
aldehyde with nano-nickel
Damian Giziński, Ilona Goszewska, Maciej Zieliński, Dmytro
Lisovytskiy, Kostiantyn Nikiforov, Joanna Masternak, Małgorzata
Zienkiewicz-Machnik, Anna Śrębowata, Jacinto Sá
PII:
DOI:
Reference:
S1566-7367(17)30182-6
doi: 10.1016/j.catcom.2017.04.048
CATCOM 5033
To appear in:
Catalysis Communications
Received date:
Revised date:
Accepted date:
8 February 2017
27 April 2017
29 April 2017
Please cite this article as: Damian Giziński, Ilona Goszewska, Maciej Zieliński, Dmytro
Lisovytskiy, Kostiantyn Nikiforov, Joanna Masternak, Małgorzata Zienkiewicz-Machnik,
Anna Śrębowata, Jacinto Sá , Chemoselective flow hydrogenation of α,β – Unsaturated
aldehyde with nano-nickel. The address for the corresponding author was captured as
affiliation for all authors. Please check if appropriate. Catcom(2017), doi: 10.1016/
j.catcom.2017.04.048
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ACCEPTED MANUSCRIPT
Chemoselective flow hydrogenation of α,β – unsaturated aldehyde with
nano-nickel
a
a
a
a
Damian Giziński , Ilona Goszewska , Maciej Zieliński , Dmytro Lisovytskiy , Kostiantyn
a
b
a
a
Nikiforov , Joanna Masternak , Małgorzata Zienkiewicz-Machnik , Anna Śrębowata ,
Jacinto Sá a,c*
a Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224
Warsaw, Poland
b Institute of Chemistry, Jan Kochanowski University, Świętokrzyska 15G, 25-406 Kielce,
Poland,
c Department of Chemistry, Ångström Laboratory, Uppsala University, 75120 Uppsala,
Sweden
*jacinto.sa@kemi.uu.se

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Abstract
Herein, it is presented a novel catalytic system for the continuous-flow chemoselective
hydrogenation of α,β – unsaturated aldehydes used in the production of high-value cosmetics
and pharmaceuticals precursors. The reaction was catalyzed by nano-nickel particles grafted
on polymeric support, synthesized via a simple, adaptable and green methodology. The
system was highly active and very selective to C=C bond saturation.
Keywords: hydrogenation in flow, nano-nickel catalyst, resin supported catalyst, selective
hydrogenation of α,β – unsaturated aldehydes

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1. Introduction
Catalytic hydrogenation is undoubtedly the most important method for the reduction of
organic compounds. The process versatility and green credentials make it an attractive
and adoptable strategy for the reduction of a plethora of organic compounds in high
yields. In the fine chemical industry, catalytic hydrogenations are performed majorly in
batch conditions [1], even if continuous flow is often preferred [2]. The use of
continuous flow improves simultaneously process profitability and green credentials
since it improves reaction atom efficiency, decreases energy costs, affords simplified
workup and large-scale synthesis (scalability) and handling of various substrates in
sequence with the same catalyst [3]. Flow methodology has been adopted for a
multitude of purposes including organic synthesis [4], biological transformation [5],
substitution [6], and conversion reactions [7].
Herein, it is presented a catalytic methodology for the chemoselective hydrogenation
of α,β – unsaturated aldehydes in flow with heterogeneous nano-nickel and hydrogen,
as catalyst and reducing agent, respectively. The catalyst was prepared via a green
route and could be used directly in the reaction. Selective hydrogenation of α,β –
unsaturated aldehydes is
a
promising strategy for the synthesis of valuable
intermediates for the pharmaceutical and fine chemical industries. The strategy implies
selective hydrogenation of only one of the functionalities (C=C or C=O) but not both.
For instance the selective hydrogenation of cinnamaldehyde (CA) yields the formation
of either hydrocinnamaldehyde (HCA) or cinnamyl alcohol (COL) (Scheme S1,
supporting information (SI)). COL is an important intermediate in cosmetics
production and HCA is applied in HIV treatment [8], while the fully hydrogenated
product (no selective path) has no industrial application.
Selective hydrogenation of CA has been widely investigated as model reaction. Most of the
reported studies relate to catalysts using supported precious metals [9]. There is a visible
tendency towards development of catalysts composed of more cost-efficient materials, namely
transition metals. Monometallic catalysts based on transition metals based on copper [10],
silver [11], or nickel [12-19] were found also active in C=C bond selective hydrogenation.
However, most of the studies on CA selective hydrogenation over nickel catalysts were
performed under stationary (batch) conditions and corroborate the above-mentioned trend

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[12-19], as given in Table S1 where Ni based catalysts CA hydrogenation chemoselective
performance in assembled [12-19].
High-pressure flow hydrogenations impose several demands in respect to catalyst design,
among them the need for large nominal size particles (low surface area support) and high
dispersion of the nano-active phase. Polymeric matrices used as supports can be modified to
allow grafting of nanomaterials post-synthetically, thus enabling the development of
monodispersed nanoscale active phases in low loading, while keeping relatively large nominal
particle sizes for the catalyst support in order to minimize pressure drop and thus energy
consumption.
2. Experimental section
2.1. Catalyst synthesis
Catalyst (NiTSNH2) preparation involved two steps, namely, synthesis of nickel
nanoparticles (NPs) and subsequent grafting on polymeric support. Nickel NPs were
obtained by chemical reduction of nickel (II) acetylacetonate with NaBH4 (reducing
agent) and trioctylphosphine oxide (TOPO) (capping agent). TOPO regulates growth
and prevents nickel NPs agglomeration. After centrifuging and washing, the NPs were
immobilized on amino groups terminated resin (Tentagel-S-NH2, BET surface area 152
m2/g and pore volume of 0.13 cm3/g) with a nominal size of 90 µm. The metal loading
was found to be 0.7 wt.% by atomic adsorption spectroscopy (AAS) and Inductively
Coupled Plasma – Optical Emission Spectroscopy (ICP-OPS). Note that the synthesis
was carried out at room temperature, in argon atmosphere with ethanol, as solvent,
which confers the process a high degree of scalability. Additionally, the polymeric
resin has expands upon contact with polar solvents, increasing functional groups
exposure and consequently increase in metal loading [20].
2.2. Catalyst characterization
Fourier-transformed Infrared (FT-IR) spectra were recorded with Nicolet 380 FT-IR
-1
spectrometer in the region of 4000 – 500 cm
using KBr pellets. X-ray photoelectron
spectroscopy (XPS) spectra were recorded with a PHI 5000 VersaProbe™ (ULVAC-PHI)
scanning ESCA Microprobe using monochromatic Al-Kα radiation (hν = 1486.6 eV) from an
X-ray source operating at 100 μm spot size, 25 W power and 15 kV acceleration voltage.

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High resolution (HR) XPS spectra were collected with a hemispherical analyzer at a pass
energy of 23.5 eV, an energy step size of 0.1 eV and a photoelectron take off angle of 45 °
with respect to the surface.
Powder X-ray diffraction (PXRD) measurements were performed employing Bragg-
Brentano configuration. This type of arrangement was provided using PANalytical
Empyrean diffraction platform, powered at 40 kV × 40 mA and equipped with a
vertical goniometer, with theta-theta geometry using Ni filtered Cu Kα radiation. Data
were collected in the range of 2θ = 5 – 95°, with step size of 0.008 ° and counting time
60 s/step.
High-resolution transmission electron microscopy (HRTEM) was performed on a FEI
Titan Cubed at 300 kV accelerating voltage. Before measurement the catalyst sample
was dispersed in pure methanol via ultrasonification. 300 mesh copper grid with holey
carbon film was immersed in the obtained suspension of the catalyst. No plasma-
cleaning was applied. Scanning electron microscopy (SEM) was carried out on a FEI
Nova NanoSEM microscope.
Energy dispersive X-ray fluorescence analysis (EDXRF) was carried out using MiniPal
4 equipment from PANalytical Co., with an Rh-tube and silicon drift detector
(resolution 145 eV). EDXRF method was used to gain information on the elemental
composition of liquid samples after catalytic experiments.
2.3. Catalytic tests
Continuous-flow hydrogenation of CA was chosen as model reaction to evaluate
catalytic performance. Note that this is to our knowledge the first application of the
selective hydrogenation of α,β – unsaturated aldehydes carried out in flow with nano-
nickel. Catalytic tests were carried out in continuous-flow micro-reactor (ThalesNano
H-Cube Pro™) that provides isothermal and isobaric conditions within operational
range of pressure and temperature up to 100 bar and 150 °C. The catalyst (150 mg)
was placed in a stainless steel cartridge (70 mm CatCart®) that enables continuous
flow of hydrogen and CA solution through the catalyst bed. The hydrogen was
generated in situ via electrolysis of water and then supplied to the reaction medium.
The 0.05 M CA ethanol solution was flown through cartridge with 0.5 mL min-1, which
results in supplying 2.5 µmol of CA per minute (3.2 µmol of prenal per minute). The
optimal reaction conditions were selected according to generation of the highest
amount of desired C=C hydrogenation product. Thus, the reactions were carried out at

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100 °C and 40 bar with CA and at 85 °C and 60 bar with prenal. The residence time
(defined as bed volume/flow rate) was calculated to be 6 min. Since the resin support
swells due to the interaction with the solvent, the catalytic experiments were initiated
after exposing materials to the solvent for 1 h. This procedure ensured that the samples
were stable in respect to support swelling. After attaining stable condition, samples
were collected at the outlet of the reactor every 30 min for 3 h and analyzed by Bruker
Scion 456-GC gas chromatograph equipped with FID. Analyzed compounds were
separated with non-polar BP-5 0.25 µm (5 % phenyl / 95 % dimethyl polysiloxane)
column.
3. Results and discussion
Changes in the –NH2 terminal groups, monitored by FT-IR spectroscopy, were used to
to confirm Ni NPs grafting to resin [21]. Figure 1 shows the primary amine –NH
-1
-1
stretching (3200-3800 cm ) and bending (1550-1700 cm ) regions. The pristine resin
shows bands at 3470 and 1650 cm-1, assigned to primary amine [22]. The addition of
Ni NPs decreased the bands intensity and induced a small shift of the –NH stretching
-1
band to lower wavenumber (3447 cm ), corroborating the idea that the Ni NPs are
covalently linked via the –NH2 terminal groups. PXRD (Figure 2) and SEM (Fig. S1,
SI) revealed that the polymer is unaltered upon loading of metal NPs, indicative of
only surface modification. The absence of new diffraction peaks in the PXRD and
discernible small particles in the SEM suggests that Ni NPs are smaller in size than 5
nm.
Thermogravimetric analysis (TGA) shows that the polymer is thermally stable up to
approximately 300°C, which appreciably higher than temperatures used in the catalyst
synthesis and chemoselective hydrogenation reactions.
HRTEM analysis showed that nickel exists in agglomerated form either on polymer
surface or inside pores (Figure 3), which impedes easy recognition of single beads.
Nevertheless, a large majority of NPs is significantly lower than 10 nm, as presented in
the Figure 3a, where NPs are in size 3-4 nm. Moreover, crystallites above 20 nm were
seldom spotted. Material features, such as presence of polymeric matrix and NPs
agglomeration, increase sample thickness above transmission limitation, making
reliable assessment that concentration/occurrence frequency are straitened.

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XPS was carried out to determine the oxidation state of the grafted NPs. Figure 4
shows Ni 2p region fitted using constrains for area intensity, full maximum half width
and doublet energy separation tabulated in the NIST database. Sample charging was
corrected using C 1s sp3 signal (284.6 eV). The dominant signal of Ni 2p3/2 located at
856.1 eV relates to Ni(OH)2. The value is roughly 0.2 eV higher than the one reported
in literature [23], which is a clear indication for the presence of nanoparticles. Previous
reports revealed that the binding energy shifts to higher energies when sample is in a
form of small nanoparticles [24]. The peak at 860.4 eV is ascribed to metallic Ni
shake-up satellite. There is a peak at low biding energy (852.9 eV) related to Ni0 [25],
which is also slightly shifted to higher energies corroborating presence of nanoparticles
[24].
Figure 5 shows catalyst activity in CA hydrogenation and selectivity to the saturated
aldehyde (desired product). The catalyst displays stable performance, with activities
related to 80% conversion of reagent and selectivity to the desired product at around 93
% after 12h of continuous reaction. It should be noticed here that only negligible
deactivation was observed during this long – term experiment. The study was
expanded to another molecule, prenal, with similar outcome (Table 1), namely high
selectivity (95%) to prenal C=C saturation, as desired product from an industrial point
of view. Note that resin without the catalyst was not active in any of the reported
reactions. Finally, the observed high selectivity towards C=C hydrogenation product
and nearly perfect carbon balance obtained suggests that C-C and C-O bond cleavage
does not occur in a significant extent in the reaction conditions used.
XRF analysis for the samples of post-reaction solutions did not show any amount of
nickel within the detection limit, i.e., no detectable metal leaching. There was also no
observable change in the PXRD pattern (Figure 2) and HR-TEM (Fig. S2, SI) of the
catalyst after reaction, suggesting high stability of the Ni NPs and resin. Finally, the
XPS show no evidence for change in the oxidation state of the Ni NPs. These findings
imply that the minor deactivation observed is related to blocking of reactive sites by
substrate and/or product, as corroborated by the appearance in the spent catalyst of two
small contributions accounting to about ca. 5% of the XPS C 1s signal (Fig. S3, SI)
ascribed to C=O (287.4 eV).
Considering current state-of-the-art (Table S1, SI) the current strategy is economically
more competitive since it employs nearly tenfold less metal than what has been
previously reported [12-19]. Moreover, CA hydrogenation is usually carried out in

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batch reactor instead of flow (desired mode) and at higher temperatures and pressures
[12-19] than those used in the present work. Physicochemical characterization of spent
catalyst (XRD, XPS, HRTEM) indicates that the catalyst is stable because there were
not observable changes in the structure and morphology of Ni NPs grafted on the resin
(Figs. 2-4) due to reaction.
Low loading of well-exposed active nano-Ni phase (0.7 wt.%) indicates high catalytic
performance in studied reaction (Fig. 5 and Table 1), where excellent stability is
obtained after 12 h of continuous reaction. The specific nature of resin support
eliminates diffusion restrictions and provides uninhibited access to the metal phase. As
a result, hydrogenated molecules approach the metal surface in a position imposed by
electronic interactions with the active phase. The strength of steric interactions is
inflected by the exposure of different metal crystal faces in the Ni clusters and nano-
particles. More corrugated Ni(110) pattern (Fig. 3) causes weaker repulsion with α,β-
unsaturated carbonyls in comparison to flat (111) surface, easing simultaneous
adsorption of both unsaturated bonds (η4 geometry). When either alkenyl and carbonyl
bonds are adsorbed via π-d mode the alkenyl hydrogenation is preferred due to kinetic
reasons [26]. Thus, selectivity of the reaction is shifted towards formation of
unsaturated aldehyde. Moreover, the results may imply that the electronic structure of
chosen metal modulated by the nanosize influences adsorption of the present substrates
via steric repulsion between C=C bond and small Ni NPs, which also assists its
selective saturation [27].
4. Conclusions
In summary, we reported to our knowledge the first nano-nickel catalyst active in
selective hydrogenation of α,β – unsaturated aldehydes in continuous flow mode. The
presented results show that nano-nickel immobilized on polymeric resin selectively
converts α,β – unsaturated aldehydes to saturated aldehyde with molecular hydrogen,
i.e., system is selective to C=C hydrogenation. The catalyst was prepared with a two-
step procedure, which enables control of size and shape of the particles and leads to
high loading active phase into a ready-to-use support. Well-exposed metal phase on
polymeric resin provides unrestricted access to the metal surface and eliminates
diffusion restrictions and clogging of the reactor.
Acknowledgements

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The authors would like to thank the National Science Centre in Poland (NCN-OPUS 8
grant no. UMO-2014/15/BST5/02094) for financial support.
References
[1] a) S. Liu, Bioprocessing Engineering (Second Edition), Chapter 4. Batch Reactor
2017, 139-178; b) A. Müller, M. Ludwig, M. Arlit, R. Lange, Cat. Today 2015, 241, 214-
220; c) D. Khairunnisa, B. Mohamed, X. Yu, J. Wu, Tetrahedron Lett. 2016, 57, 3965-
3977.
[2] D. Snead, T. F. Jamison, Chem. Sci. 2013, 4, 2822- 2827
[3] C. Ayats, A. H. Henseler, M. A. Pericàs, ChemSusChem 2012, 5, 320-325.
[4] M. Movsisyau, M. M. A. Moens, C.V. Stevens, Adv. Heterocyclic Chem., 2016, 119,
25-55.
[5] Z. Galla, F. Beke, E. Forró, F. Fülöp, J. Mol. Catal. B: Enzym. 2016, 123, 107-112.
[6] M. Charaschanya, A.R. Bogdan, Y. Wang, S.W. Djuric, Tetrahedron Lett. 2016, 57,
1035-1039.
[7] J. Wu, J. A. Kozak, F. Simeon, T. A. Hatton, T. F. Jamison, Chem. Sci. 2014, 5, 1227-
1231.
[8] T. Szumełda, A. Drelinkiewicz, R. Kosydar, J. Gurgul, Appl. Catal. A: Gen. 2014,
487, 1-15.
[9] a) C. Espro, A. Donato, S. Galvagno, G. Neri, React. Kinet., Mech. Cat. 2016, 118,
223-233; b) F. Jiang, J. Cai, B. Liu, Y. Xu, X. Liu, RSC Adv. 2016, 6, 75541- 75551; c)
A.S. Nagpure, L. Gurrala, P. Gogoi, S.V. Chilukuri, RSC Adv. 2016, 6, 44333- 44340; d)
Q. Zheng, D. Wang, F. Yuan, Q. Han, Y. Dong, Y. Liu, X. Niu, Y. Zhu, Catal. Lett.
2016, 146, 1636-1543.
[10] C. M. Piqueras, V. Puccia, D.A. Vega, M.A. Volpe, Appl. Catal. B: Environ., 2016,
185, 265-271.
[11] E. Plessers, D.E. De Vos, M.B.J. Roeffaers, J. Catal., 2016, 340, 136-143
[12] R. Xie, G. Fan, Q. Ma, L. Yang, F. Li, J. Mater. Chem. A, 2014, 2, 7880
[13] M.G. Prakash, R. Mahalakshmy, K.R. Krishnamurthy, B. Viswanathan, Catal. Sci.
Technol., 2015, 5, 3313
[14] M.G. Prakash, R. Mahalakshmy, K.R. Krishnamurthy, B. Viswanathan, Catal.
Today, 2016, 263, 105-111

ACCEPTED MANUSCRIPT
[15] S. Gryglewicz, A. Śliwka, J. Ćwikła, G. Gryglewicz, Catal. Lett., 2014, 144, 62-69
[16] S. Bhogeswararao, V.P. Kumar, K.V.R. Chary, D. Srinivas, Catal. Lett., 2013, 143,
1266-1276
[17] L.J. Malobela, J. Heveling, W.G. Augustyn, M. Cele, Ind. Eng. Chem. Res., 2014,
53, 13910-13919
[18] S. Rana, S.B. Jonnalagadda, RSC Adv., 2017, 7, 2869
[19] L. Ceatra, O.C. Parvulescu, I. Rodrigez Ramos, T. Dobre, Ind. Eng. Chem. Res.,
2016, 55, 1491-1502
[20] F. Liguori, C. Monero-Marrodan, P. Barbaro, Chinese J. Catal. 2015, 36, 1157-
1169.
[21] C. Finetti, L. Sola, M. Pezzullo, D. Prosperi, M. Colombo, B. Riva, S. Avvakumova,
C. Morasso, S. Picciolini, M. Chiari, Langmuir 2016, 32, 7435-7441.
[22] N. Thanh, L. Green, Nano Today 2010, 5, 213-230.
[23] a) B. P. Loechel, H. H. Strehblow, J. Electrochem. Soc. 1984, 131, 713; b) J.C. Klein,
D.M. Hercules, J. Catal. 1983, 82, 424.
[24] a) H. Zhang, Q. Fu, Y. Yao, Z. Zhang, T. Ma, D. Tan, X. Bao, Langmuir 2008,
24, 10874-10878; b) I. Lopez-Salido, D. C. Lin, R. Dietsche, N. Bertram, Y. D. Kim, J.
Phys. Chem. B 2006, 110, 1128-1136; c) M. Ramstedt, P. Franklyn, Surf. Interface
Anal. 2010, 42, 855-858; d) C. Paun, G. Słowik, E. Lewin, J. Sá, RSC Adv. 2016, 90,
87564-87568.
[25] a) S. O. Grim, L. J. Matienzo, W. E. Swartz Jr., J. Am. Chem. Soc. 1972, 94, pp 5116–
5117, b) G. Ertl, R. Hierl, H. Knozinger, N. Thiele, H.P. Urbach, Appl. Surf. Sci. 1980, 5,49-
64.
[26] F. Delbeq, P. Sautet, J. Catal., 1995, 162, 217
[27] a) S. He, L. Xie, M. Che, H.C. Chan, L. Yang, Z. Shi, Y. Tang, Q. Gao, J. Mol. Catal. A:
Chem., 2016, 425, 248-254 b) P. Gallezot, D. Richard, Cat. Rev.- Sci. Eng., 1998, 40:1-2, 81-
126

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Figures captions
Figure 1. FT-IR spectra depicting the characteristic primary amine -NH2 vibrations for
polymeric resin before (blue) and after (red) grafting with the Ni NPs.
Figure 2. PXRD patterns for polymeric resin before (blue) and , NiTSNH2 as prepared after
(red) grafting with the Ni NPs and spent- NiTSNH2 (green).
Figure 3. HRTEM overall view (a) and magnification of the selected area with FFT image
insert (b) showing Ni NPs in the polymer matrix. The crystal structure was identified as nickel
ffc, a=3.52 Å
Figure 4. XPS of nickel catalyst after preparation and after catalyst reaction. Narrow scan of
Ni 2p region.
Figure 5. Catalytic activity of the nano-nickel catalyst in the chemoselective hydrogenation of
cinnamaldehyde to hydrocinnamaldehyde.
Table 1. Summary of the catalytic activities and selectivity for chemoselective hydrogenation
of α,β – unsaturated aldehydes after 3h.

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Figure 1
Figure 2

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Figure 3

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Figure 4
3
2
1
0
100
80
60
40
20
0
Activity
Selectivity towards HCA
0
1
2
3
4
5
6
7
8
9
10 11 12
Time on steam (h)
Figure 5

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Table 1
Selectivity, %
Activity,
Flow rate,
mL min-1
Substrate
Conv., %
T, °C
p, bar
µmol min-1
C=C
C=O
Complete
Reaction scheme
saturation saturation saturation
cinnamaldehyde
prenal
2.3
1.2
87
37
93
95
-
-
7
5
100
85
40
60
0.5
0.5

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Graphical abstract

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Highlights
 Ready-to-use Ni NPs immobilized on resin catalyst for flow hydrogenation
 Simple, adaptable and green methodology for catalyst synthesis
 High selectivity towards unsaturated aldehyde
 Low metal loading
 High catalytic performance