Imidazolium-based ionic liquid immobilized on functionalized magnetic hydrotalcite (Fe3O4/HT-IM): as an efficient heterogeneous magnetic nanocatalyst for chemical fixation of carbon dioxide under green conditions

Article abstract of DOI:10.1039/d0nj05225f

A reusable, eco-friendly, long-lived and efficient nanocatalyst, imidazolium-based ionic liquid immobilized on functionalized magnetic hydrotalcite (Fe3O4/HT-IM, IM is known as imidazolium-based melamine), was successfully introduced. The structure of the synthesized nanocatalyst was characterized by several techniques which revealed a plate-like shape with an average particle size of approximately 50 nm and also the presence of acidic sites (site density: 12 mmol g-1). The catalytic activity of Fe3O4/HT-IM was explored in the chemical fixation reaction of carbon dioxide towards the preparation of cyclic carbonates under optimized reaction conditions at 100 °C, 0.7 MPa and 1.6 mol% of the nanocatalyst. This reaction was conducted without using any metal, additive, toxic reagents and solvent/co-catalyst which provides mild and green conditions from the standpoint of green chemistry. Owing to having acidic-basic sites which can simultaneously accelerate the ring-opening of the epoxy ring and incorporation of CO2, this catalyst is attractive and suitable for this reaction. In particular, the prepared catalyst can be easily separated using an external magnetic field and reused over six times without any significant loss in catalytic performance and selectivity. This proves its great potential to be implemented for industrial purposes as a green catalyst. This journal is

Full text of DOI:10.1039/d0nj05225f

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Chechia Hu, Tzu-Jen Lin et al.
Yellowish and blue luminescent graphene oxide quantum dots
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DOI: 10.1039/D0NJ05225F
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Imidazolium-based ionic liquid immobilized on functionalized
magnetic hydrotalcite (Fe3O4/HT-IM): as an efficient heterogeneous
magnetic nanocatalyst for chemical fixation of carbon dioxide
under green conditions
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
Reza Khalifeh,*a Zeinab Zarei a and Maryam Rajabzadeh a
In this context, a reusable, eco-friendly, long-lived and efficient nanocatalyst, imidazolium-based ionic liquid immobilized on
functionalized magnetic hydrotalcite (Fe3O4/HT-IM), IM is known as imidazolium-based melamine, was successfully
introduced. The structure of the synthesized nanocatalyst was characterized by several techniques which revealed a plate-
like shape with average particle size of approximately 50 nm and also the presence of acidic sites (site density: 12 mmol g-
1). The catalytic activity of Fe3O4/HT-IM was explored in chemical fixation reaction of carbon dioxide towards the
preparation of cyclic carbonates under optimized reaction conditions at 100 °C, 0.7 MPa and 1.6 mol% of the nanocatalyst.
This reaction was conducted without using any metal, additive, toxic reagents and solvent/co-catalyst which provides a mild
and green condition from the standpoint of green chemistry. Owing to having acidic-basic sites which can simultaneously
accelerate the ring-opening of the epoxy ring and incorporation of CO2, this catalyst is attractive and suitable for this
reaction. In particular, the prepared catalyst can be easily separated using external magnetic field and reused over six times
without any significant loss in catalytic performance and selectivity. This proves its great potential to be implemented for
industrial purposes as a green catalyst.
compounds, N-formylation and N-methylation of amines using CO2,
nucleophilic reactions of CO2 with aziridines or propargylic amines
that require harsh reaction condition, supercritical conditions and
Introduction
During the last two decades of the twentieth century, in order to
mitigate the greenhouse effect and environmental global warming,
chemical fixation of carbon dioxide, as the earth’s most unfavorable
industrial abundant carbon resource and its conversion into valuable,
useful, inexhaustible and nontoxic chemical molecules, in modern
organic chemistry is among the hottest research topics in both
industries and universities. It is a controversial challenge which has
attracted continuous attentions from three viewpoints of
"environmental problems", "sustainable society" and "atom
economy", as far as we are aware.1, 2 Therefore today, efforts to
increase fixation or capture of CO2 are highly desirable as regards the
toxic solvent.9 Also, till now, various methodologies have been
reported using a mixture of hydrogen-bond donors, metal catalysts,
zeolites, ionic liquids, transition metal complexes, alkaline metal
salts, phosphonium salts, metal oxides, bicyclic guanidines, silver
NHC complexes, functional polymers, polyoxometalates,
metalloporphyrins, metal-organic frameworks (MOFs), nanoparticles
and so on for this transformation reaction.9-15 Although many of
these reactions are highly challenging for researchers and suffer from
serious desirable tasks such as low rate of catalyst stability/reactivity,
air and moisture sensitivity, the need for a co-solvent/additive, or
high pressure, temperature or cost, lack of satisfactory yields, and
less green synthesis routes, exhaustive separation of products, their
recovery and reutilization, low biodegradability, which confine their
applications in many cases. Thus, this has spurred a number of
researchers to explore the research on the development of an
environmentally benign and effective nanocatalyst which resolves
these problems and enables operation in mild conditions and
simultaneously culminates in easy product separation and operation
simplification. In spite of these advances, some problems have yet to
be resolved. It is worth nothing that there have been a lot of reports
as regards heterogeneous catalysts or nanocatalysts which catalyze
this reaction so far.16-19 Therefore, it is still in its infancy and it is an
attractive subject to focus on this transformation reaction using
various nanocatalysts.
4
sustainable chemistry and Green Chemistry.3, In this regard,
conversion route through coupling CO2 with epoxide as the initial
material is a recognized environment-friendly route which has high
atom economy without any by-products to afford cyclic carbonates.
These are extensively adopted as intermediates, electrolytic
elements, monomer of polycarbonates, green polar aprotic solvents
and so on.5-8 To the best of our knowledge during past decades,
numerous researchers have been enthusiastic to perform various
procedures like C-C bond formation of CO2 with various organo
a. Department of Chemistry, Shiraz University of Technology, Shiraz 71555-313,
Iran.
Phone: +987117354520; Fax:+987117354520. E-mail: khalifeh@sutech.ac.ir.
†
ORCID: 0000-0003-3060-5556.
Electronic Supplementary Information (ESI) available: [details of any supplementary
information available should be included here]. See DOI: 10.1039/x0xx00000x
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The layered double hydroxide materials (LDH) like hydrotalcite with polymerization as may be expected. There is no report regarding
View Article Online
general formula [M2+
M
x(OH)2]x+(An−)x/n·mH2O which consist of ionic liquid immobilized on magnetic hydrotalcite and its application
3+
DOI: 10.1039/D0NJ05225F
1−x
cation ions such as Al3+, Fe3+, Fe 2+ and Mg +2, etc, water molecules, in chemical fixation of CO2. Finally, we believe that this catalyst may
anions and layer sheets are a versatile support material due to its have great potential for other applications in years to come.
structure and acido-basic sites and attracted enormous attention in
recent years.20 In the course of our research, it has been interestingly
found that hydrotalcite can also play the most important role in the
Results and discussion
capture CO2 which can dramatically promote this reaction owing to
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In this project, the Fe3O4/HT-IM nanocatalyst was initially
(Lewis) acid -base sites. It was proposed that Lewis acid sites (Zn2+,
synthesized through five steps as shown in Scheme 1. In the first step,
Al3+, Co2+) can chemically activate the alkoxide intermediate, and
the HT (I) (molar ratio Mg/Al = 2) was synthesized using the co-
precipitation method.20 Then, the prepared HT (I) was magnetized by
surprisingly the base sites will take advantage of the subsequent ring-
opening of the epoxide by nucleophile.21, 22
iron salt solutions to achieve Fe3O4/HT (II). In the following step, the
3-Chloropropyltrimethoxysilane linker was chemically grafted on the
surface hydroxyl groups of Fe3O4/HT (II). Afterward, in order to
obtain the nanocatalyst with NH groups (the ability for further
hydrogen-bonding), melamine was grafted on the surface of the
functionalized Fe3O4/HT (II). In the final stage, the prepared
Fe3O4/HT-(CH2)3-Melamine (IV) was designed as an ionic liquid-
bearing imidazolium ring incorporating Br- anion. Then, the structure
and morphology of the obtained solid material nanocatalyst
(Fe3O4/HT-IM) were fully characterized by FT-IR, XRD, TPR-H2, zeta
potential, TEM, FESEM, EDX, TPD and TGA techniques.
Based on literature, it is very interesting to note that chemical
fixation of CO2 has high activation barrier due to its high
thermodynamic stability and kinetic inertness of CO2 and need a
Lewis acid species and a nucleophile.23 On the other hand, the
presence of special five member ring of imidazole, anions and
NH2/NH groups could be useful for the further ring opening of
epoxide substrates using the hydrogen bond on the oxygen atom of
the epoxide which will improve catalytic activity and thus accelerate
24-26
this transformation reaction.2,
Ionic liquids (ILs), as a hot
emerging research area, with unique charming features and their
outstanding physicochemical properties such as low melting
temperature, negligible vapor pressure, low toxicity, suitable
solubility, high thermal and chemical stability, good ion conductivity
as well as catalytic activity and selectivity, etc, and as a new style of
green material and one of most valuable key precursor compounds
of catalysts have been extensively discussed and provided new
opportunities.26 Producing a considerable amount of waste materials
and removing them is one of the major disadvantages of using ILs
directly, which makes the process inappropriate from the
environmental point of view. Consequently, immobilization of ILs on
different solid supports, as one of the innovative and modern
strategies, leads to a combination of the benefits of ILs and
heterogeneous support nanomaterials thanks to enhancing the
contact surface between ILs and compounds, and making a proper
heterogeneous framework.27
FeCl3.6 H2O
FeCl2.4H2O
NaOH
(5%)
60 °C
24 h
Fe3O4/HT
(II)
80 °C, Ar, 24 h
HT
(I)
toluene
12h, reflux
3-Chloropropyl
trimethoxysilane
Cl
H2N
N
NH2
N
N
Cl
Fe3O4/HT-(CH2 -Cl
NH2
H2N
N
NH2
)
(III)
3
N
N
NaOH
EtOH, 12h, reflux
HN
HN
In continuation of our works on the synthesis and development of
magnetic, and eco-friendly nanocatalyst and their application in
organic reactions,28-41 herein, we were willing to extend preparation
of an innovative, highly potential, thermostable, facile and
sustainable nanocatalyst based on hydrotalcite as the solid support
which exhibits attractive merits for chemical fixation of CO2 with
epoxy (as coupling partner) to give resultant five membered-
carbonate under rather straightforward ambient reaction conditions
without any need of solvent/cocatalyst. For this goal, in the present
work, we initially synthesized magnetic hydrotalcite, and then
modified it chemically with melamine (moieties bearing hydrogen-
bond-donor), and subsequently an ionic liquid structure with
imidazole ring was designed (Scheme 1), with two essential goals to
create more powerful catalysts: 1) easy and quick separation of
nanocatalyst/ or product, 2) excellent ability to capture carbon
dioxide, and accelerate the reaction. We were amazed to realize that
because of bifunctional property of obtained nanocatalysts a
concerted action on both CO2 and substrates can accelerate this
reaction, and result in the cyclic carbonates instead of the
N
N
Fe3O4/HT-(CH2 -Melamine
)
(IV)
3
NH2
N
H2N
hexane K2CO3 100 °C, 12 h
,
1,6-diboromo
K2CO3 100 °C, 12 h
,
1-methylimidazole
Me
Me
N
N
.9H2O
.6H2O
Al(NO3)3
CO3
N
-2
N
NH
N
H
Mg(NO3)3
Fe3O4
HN
N
N
N
N
H
N
N
N
NH
NaOH
Br-
HN
N
N
N
NaHCO3
Me
Fe3O4/HT-IM
(V)
N
n-Hexane
Me
propyltrimethoxysilane
Scheme 1. An overview on the preparation of the Fe3O4/HT-IM
nanocatalyst.
The FT-IR spectra of Fe3O4/HT (II), Fe3O4/HT-(CH2)3-Cl (III),
Fe3O4/HT-(CH2)3- Melamine (IV) and Fe3O4/HT-IM (V) nanocatalyst
were illustrated and compared, respectively (Figure 1). According to
the spectra, Figure 1a exhibited many peaks, a broad band at 3450 –
3400 cm-1 which was due to the bending vibration mode of
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symmetric stretching vibration of Mg-OH and Al-OH which are on the patterns. The first step below 100 °C is related to removal of
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surface of HT (I). In addition, a peak at 1620 cm-1 is possibly arisen physically adsorbed water in addition to dehydration of the surface
DOI: 10.1039/D0NJ05225F
from stretching vibration of coordinated water molecules in the OH groups (weight loss 1.84 %). The second weight loss 24.56 %
structure of HT (I). Characteristic adsorption bands at 1367 cm-1 and which was because of the organic segment, happened in the range
672 cm-1 correspond to the existence of carbonate ions between of 100 °C to 500 °C. The appearance of the third step up to 500 °C
layers of hydrotalcite and angular bending mode of carbonate was related to the last stage of the fully thermal decomposition of
species (Figure 1a). In addition, it was pointed out that the stretching the structure (weight loss 7.33 % (Figure 2a). The TGA plot of
vibrations of Fe-O bonds overlapped with those of Al-O and Mg-O Fe3O4/HT-(CH2)3-Melamine (IV) also showed three remarkable
bonds. In the spectrum of Figure 1b, the presence of grafted (3- steps. The first step at 25- 140 °C (due to the removal of the adsorbed
chloropropyl)trimethoxysilane linker was confirmed by the water, 2.7%), and second step was observed at 140 – 510 °C with
appearance of a slight broad band around 3100- 2850 cm-1 owing to 31.09 % weight loss (consisting of two typical steps related to organic
the C-H stretching vibrations whereas somewhat increasing intensity units). Thanks to the cross-linked nature of melamine and
of band around 1111 cm-1 was assigned to the C-C stretching intermolecular hydrogen bonding of Fe3O4/HT-(CH2)3-Melamine
vibration of (CH2) groups. It is noted that the characteristic peak (IV), it exhibited an enhanced thermal. Hence, the TGA curves also
which is correlating with Si-O stretching vibrations cannot be proved the successful grafting of melamine. Above this temperature,
distinguished (in the range of 680-670 cm-1) because of the exhibited the final decomposition step happened at about 510 °C (weight loss
broad band of the symmetric stretching vibration of M-O bonds. 11.14% (Figure 2b). Besides, the TGA analysis of the Fe3O4/HT-IM (V)
Also, after covalent anchoring of melamine, in the spectrum of nanocatalyst exhibited three significant patterns. The first mass loss
Fe3O4/HT-(CH2)3-Melamine (IV) (Figure 1c), a new absorption band occurred at 50 – 160 °C (owing to the removal of the surface
was appeared at 1563 cm-1, indicative of the NCN bending of the adsorbed water). The second step of the mass loss is owing to the
melamine, suggesting the grafted melamine on the surface of the grafted ligand which started to decompose from 160 °C to 580 °C. It
functionalized Fe3O4/HT-(CH2)3-Cl (III). In Figure 1d, the appearance consisted of two steps because of the presence of two melamine and
of a characteristic active strong absorption band at 1206 cm-1 imidazoline segments (weight loss 37.66%). Lastly, final
(plausibly due to the bending vibration of C-H bonds), presumably decomposition of the catalyst occurred between the temperature
indicated the presence of C-H in-plane of imidazole ring, and also a ranges of 580 – 800 °C (2.39%). These findings demonstrated good
decrease in the peak intensity in the range of 3445-3400 cm-1 thermal stability of Fe3O4/HT-IM nanocatalyst up to 160 °C.
provided an evidence for grafting 1-methyl imidazole. All of obtained
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results verify that the structure of the (Fe3O4/HT-IM) (V)
nanocatalyst has truly been proposed (Figure 1d), and also agreed
well with data obtained in TGA.
Figure 2. TGA thermograms of (a) Fe3O4/HT-(CH2)3-Cl (III), (b)
Fe3O4/HT-(CH2)3-Melamine (IV), and (c) Fe3O4/HT-IM (V)
nanocatalyst.
To prove surface modification of Fe3O4/HT (II), zeta potential study
was conducted as represented in Figure 3. The zeta potential of
Figure 1. FT-IR spectra of (a) Fe3O4/HT (II), (b) Fe3O4/HT-(CH2)3-Cl Fe3O4/HT (II) was considered to be approximately 0.9 mV as the
(III), (c) Fe3O4/HT-(CH2)3-Melamine (IV), and (d) Fe3O4/HT-IM (V).
mean value, while the following modification was -12.6 mV in the
Fe3O4/HT-IM (V) nanocatalyst. This decline exhibited the successful
modification of the surface of Fe3O4/HT (II). It should be emphasized
that the huge negative surface charge owing to the repulsive force
among particles can indicate the high stability of the Fe3O4/HT-IM
(V) nanocatalyst than Fe3O4/HT (II).
In order to evaluate the thermal stability of the obtained materials,
TGA analysis was performed under the nitrogen atmosphere with
heating rate of 10 °C min-1 between temperature range from 25 to
800 °C for each sample, as shown in Figure 2. The TGA plot of
Fe3O4/HT-(CH2)3-Cl (III) exhibited three significant weight loss
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Figure 3. Zeta potential analysis for (a) Fe3O4/HT (II), and (b)
Fe3O4/HT-IM (V) nanocatalyst.
Figure 4. The XRD patterns of (a) Fe3O4/HT (II), and (b) Fe3O4/HT-IM
In order to verify the crystalline structures of Fe3O4/HT (II) and (V).
Fe3O4/HT-IM (V) nanocatalyst, X-ray diffraction (XRD) analysis was
performed (at 2Ɵ = 0 – 90), as shown in Figure 4. As regards
Fe3O4/HT (II) (Figure 4a), many characteristic diffraction peaks were
observed at 2θ = 11.2° (003), 22.6° (006), 34.5° (012), 38.0° (018),
60.3° (110), 61.5° (113), all of which were manifestations of the
presence of hydrotalcite. Also, the crystalline peaks occurring at 2θ =
29.8° (220), 35.4° (311), 43.3° (400), 53.8° (422), 57.3° (511), 62.9°
(440), 75.5° (622) demonstrated the cubic structure of Fe3O4 MNPs
(JCPDS: 19-0629). It is interesting that the XRD pattern of Fe3O4/HT-
IM (V) (Figure 4b) is similar to its parent material, Fe3O4/HT(II) that
has been used as support, showing no change crystallinity took place
after the functionalization of the surface of Fe3O4/HT (II). They
match well with each other which indicates the high chemical
stability of Fe3O4/HT(II). The basal spacing d(003) (which is the
characteristic of hydrotalcite-like materials) of Fe3O4/HT (II) was
7.51 nm which increased to 7.61 nm probably due to the placement
of bromide ions between the layers of the Fe3O4/HT-IM (V)
nanocatalyst. This proposal was further confirmed with the increased
intensity of the (006) reflection peak relative to (003) in the
Fe3O4/HT-IM (V) nanocatalyst compared to Fe3O4/HT(II).
To understand the morphology of the as-synthesized solid materials,
FESEM spectrum of the Fe3O4/HT(II) and Fe3O4/HT-IM (V) at
different magnifications have been recorded in Figure 5. It is clear
that HT has a plate-like shape, as noticed in Fig. 5a and 5b.
Furthermore, the presence of Fe, Mg and Al confirmed the successful
preparation of Fe3O4/HT (II) as EDX analysis shown (Figure 5c). Also
clearly shown in Figure 5d, the coexistence of Si strongly approved To have a more profound understanding of the structural
the covalent grafting of 3-choloropropyltrimethoxysilae linker on the morphology of synthesized Fe3O4/HT-IM (V) nanocatalyst, the
surface of Fe3O4/HT (II), and well proved that no impurity in the transmission electron microscopic image was performed. As can be
Figure 5. FESEM images of (a) Fe3O4/HT (II), and (b) Fe3O4/HT-IM (V)
at different magnifications and EDX analysis of (c) Fe3O4/HT (II), and
(d)Fe3O4/HT-IM (V)
structure of the obtained solid materials was shown.
seen, the figure 6 displayed the typical layered platelet-like
morphology, confirming the presence of HT (I) without any
agglomeration while Fe3O4 NPs are distributed over the surface of it.
Also, it was shown that the average particle size was approximately
50 nm.
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Table 1. Total quantities of acid sites calculated from the TPD
profiles.
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DOI: 10.1039/D0NJ05225F
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Sample
Total acidity (mmol/g)
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7
8
Fe3O4/HT (II)
11
12
Fe3O4/HT-IM (V)
9
Temperature programmed reduction (TPR) was carried out in order
to study the reducible metal(s) in the Fe3O4/HT (II) and Fe3O4/HT-
IM (V) nanocatalyst. At first, in TPR run, Ar insertion process was
performed (on 25 mg of each catalyst) at 300 °C for 1h. Subsequently,
under the same atmosphere, samples were lowered to room
temperature. Lastly, samples were exposed with 5.0% H2/Ar mixture
while the temperature ramped from ambient (∼35 °C) to 900 °C (at
a heating rate of 10 °C/min). After the run, the amount of H2
consumed (TCD signal) in the reduction process was plotted as a
function of temperature, and was determined using calculation
under the area under each peak (Table 2). As presented in Figure 8,
TPR spectrum obtained for Fe3O4/HT(II) and Fe3O4/HT-IM (V)
nanocatalyst are rather similar, and can be deconvoluted into four
broad distinct reduction peaks at a wide range from 300 to 342 °C,
500 to 700 °C and above from 800 °C in the structure of both samples.
According to the previous studies, a peak between 300-342 °C, could
well reflect the reduction of Fe+3 to Fe+2 species.42More specifically,
a broad peak reduction of transformations of magnetite to metallic
iron Fe3O4 to FeO/ Fe which consisted of two very broad peaks well
spitted reduction peaks, appeared between at 500- 700 °C. Also, the
peak centered above 800 °C was attributed to the entire reduction
of Fe species in center. Based on previous study, no reduction peak
was observed related to HT structure.43 It should be pointed out that
the reduction peak of Fe3O4/HT-IM (V) nanocatalyst was moved to
higher temperatures towards Fe3O4/HT(II), which can be probably a
result of the presence of imidazoline ring that retarded reduction
process. It has been observed that the H2 consumption of Fe3O4/HT
(II) and Fe3O4/HT-IM (V) nanocatalysts were 3.1 mmol/g and 2.6
mmol/g (Table 2), respectively.
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Figure 6. TEM image of Fe3O4/HT-IM (V) nanocatlyst.
In order to study type and strength of the total acid sites, TPD
experiments were performed. For this purpose, at first, pure helium
was purged on 40 mg of each sample at 300 °C for 1h. Following that,
after cooling to 110 °C, 5% NH3/He was passed at 110°C for at least
30 min, and finally the active sites of samples were completely
removed from loosely bound ammonia by dosing He stream for 30
min at 110 °C, and heated again from 110 to 800 °C at a heating rate
of 10 °C/min in a flow of He. As shown in Figure 7a, Fe3O4/HT (II)
curve showed three desorption peaks at around 130-239 °C, 300- 500
°C and above 500 °C, which resulted from mostly weak Brønsted acid
sites on the surface of HT (due to physisorbed and chemisorbed
ammonia). The moderate Lewis acid sites on the surface of HT might
be related to the Al3+-O2--Mg2+ species present in the structure of the
mixed oxides and Al3+ cations in octahedral sites and stronger Lewis
acid sites which appeared at temperature above 500 °C, respectively.
Also as could be seen in Figure 7b, Fe3O4/HT-IM (V) nanocatalyst
exhibited similar TPD profile accompanied with three NH3 distinct
desorption peaks, while there was a further rise in the intensity of
the peak above 500 °C owing to the generation of new strong acid
sites (N+ sites of ionic liquid) and hydrogen bonding of the surface
with the adsorbed NH3, which are responsible for the increase in
acidity. It was highlighted that the total acidity of Fe3O4/HT (II) and
Fe3O4/HT-IM (V) nanocatalysts were 11 mmol/g and 12 mmol/g,
respectively (Table 1).
Figure 8. TPR-H2 profiles of (a) Fe3O4/HT (II), and (b) Fe3O4/HT-IM
(V) nanocatalyst.
Table 2. Total amount of H2 consumed calculated for each peak
from the TPR profiles.
Sample
Amount of H2 uptaked
(mmol/g)
Ref.
42, 43
Fe3O4/HT (II)
3.1
2.6
Fe3O4/HT-IM (V)
-
Figure 7. NH3-TPD profiles of (a) Fe3O4/HT (II), and (b) Fe3O4/HT-IM
(V) nanocatalyst.
After successfully synthesizing the Fe3O4/HT-IM (V) nanocatalyst and
conforming its structure properly, the catalytic performance of this
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-
nanocatalyst was examined in the coupling reaction of styrene oxide tetrafluoroborate (n-BuTA BF4 ), heteropolyacid (HPA) and sodium
View Article Online
and CO2. To explore the optimum conditions to achieve the acetate (NaOAc) have proved to be ineffectiDveO.I:B1y0c.1o0n3t9r/aDs0tN, tJe0t5r2a2-5nF-
maximum yield of cyclic carbonates by this catalytic system, initial butylammonium bromide (TBAB) displayed superior activity
studies were conducted by performing the model reaction at compared to the other co-catalysts under similar conditions. It was
different conditions. The initial research was performed with respect obviously selected as the best option as is shown in Table 3 entries
to the considerable effects of hydrogen bonding and NH/ NH2 groups 2-5. As regards green chemistry and in order to continue our efforts
on the reaction yield and reaction rate based on literature. We have to achieve more optimal conditions, we came to conclusion to
firstly investigated the catalytic activity of Fe3O4/HT-(CH2)3- remove TBAB to improve the reaction conditions. Subsequently, we
Melamine (IV) on coupling reaction of styrene oxide and CO2 which benefited from the combination of imidazole ring and bromide anion
were selected as a model substrate, and the results are outlined in which have remarkably positive synergistic impact on the efficiency
Table 3. Initially, the reaction was studied without the use of any co- of this catalyst system as regards yield. In this regard, Fe3O4/HT-IM
catalyst, resulting in the cyclic carbonate in lower yields, only 50% (V) nanocatalyst was designed to be as an ionic liquid accomplished
(Table 3, entry 1). Hence, numerous co-catalysts were used in order by Br- anion (Scheme 1).
4
5
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7
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9
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60
to raise yield. Under the given conditions, tetrabutyl-n-ammonium
Table 3. The coupling reaction of styrene oxide and CO2 in the presence of a Fe3O4/HTO(CH2)3 Melamine (IV) catalyst
under various conditions.
-
O
e
e am ne
F
HT
H
2 3M l
i
3O4/
C
.
(
)
O
O
+
CO2
,
,
,
°
o ca a
s
a
t ly t F 1
1 MP
C
S
00
C
Reaction Conditions
Yield
(%)
Entry
Time (h)
Amount of catalyst
(mol%)
Catalyst
Press. (MPa)
Temp. (°C)
Co catalyst
1
2
3
4
5
Fe3O4/HT-(CH2)3 Melamine
Fe3O4/HT-(CH2)3 Melamine
Fe3O4/HT-(CH2)3 Melamine
Fe3O4/HT-(CH2)3 Melamine
Fe3O4/HT-(CH2)3 Melamine
1
1
1
1
1
100
100
100
100
100
1.6
1.6
1.6
1.6
1.6
-
n-BuTA BF4
HPA
50
30
-
8
8
8
8
8
-
NaOAc
TBAB
60
98
In the next stage, different contributing factors to the model reaction obtained in the reaction yield with raising or lowering amount of
such as temperature and pressure of carbon dioxide, which affect the catalyst (Figure 11). These results led us to believe that using 100 °C
yields of cyclic carbonate, were studied. This nanocatalyst (V) was temperature under 0.7 MPa CO2 pressure with catalyst loading of 1.6
implemented at different pressures and the results under the same mol% for 8 h, is identified as the best reaction conditions that give
conditions at 100 °C and 1.6 mol% of the nanocatalyst for 8 h maximum yield with 100% selectivity, as can be obviously seen from
indicated that the best pressure was achieved using 0.7 MPa of CO2 the Figure 11.
charge. This way the main product was obtained with staggering 96
% yield and 100% selectivity. It is noteworthy that a rise in pressure
to 1 MPa had no remarkable impact on the yield of the reaction;
while a higher pressure (1.5 MPa) decreased the reaction yield from
96 to 60 % (Figure 9). A possible explanation for this decline might be
the fact that excessive pressure of CO2 may retard the interaction
between epoxy styrene and Fe3O4/HT-IM (V) nanocatalyst.
Furthermore, under the same conditions at 0.7 MPa and 1.6 mol% of
the nanocatalyst for 8 h, the influence of temperature on the model
reaction was also investigated in the range of 30–100 °C. The results
indicated that a decrease in the temperature to 30 °C would result in
a low yield (30 %) (Figure 10), and thus, 100 °C was selected to be the
optimal temperature.
Subsequently, the effect of the amount of the catalyst was
ascertained on model reaction under the same conditions at 100 °C
and 0.7 MPa for 8 h. Considering different figures for the catalyst
amount proved that 1.6 mol% of the Fe3O4/HT-IM (V) nanocatalyst
will result in extremely excellent yield with 100% selectivity for the
Figure 9. The coupling reaction of styrene oxide and CO2 in the
presence of 1.6 mol% of Fe3O4/HT-IM (V) nanocatalyst under various
pressures at 100 °C for 8 h.
cyclic carbonate formation, whereas no further increase was
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noticeable that the electron withdrawing properties of the chlorine
View Article Online
atom led to facilitated nucleophilic attack at DthOeI:e1p0o.1x0i3d9e/Dri0nNgJc0a5r2b2o5nF
atoms and as a result the corresponding product was obtained at
approximately 100% yield (Table 4, entry 7). By contrast, when
cyclohexane oxide was used, the related cyclic carbonate required 10
h to reach 60% yield of the corresponding cyclic carbonate (Table 4,
entry 8), which can be attributed to the higher hindrance resulting
from the two rings (Table 4, entry 8).
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O
O
Fe
3O4/HT-IM
O
O
+
CO2
MPa
S.F, 100 °C, 0.7
R
R
Scheme 2. Synthesis of cyclic carbonate derivatives in the presence
of Fe3O4/HT-IM (V) nanocatlyst.
Figure 10. The coupling reaction of styrene oxide and CO2 in the
presence of 1.6 mol% of Fe3O4/HT-IM (V) nanocatalyst under various
temperatures at 0.7 MPa for 8 h.
Table 4. Synthesis of different structurally-cyclic carbonates using
the Fe3O4/HT-IM nanocatalyst under solvent-free conditions.
Time
(h)
Yield
(%)
Entry
Epoxide
Product
O
O
O
O
1
8
96
95
O
O
O
O
O
O
2
10
O
O
O
O
O
O
3
9
96
Figure 11. The coupling reaction of styrene oxide and CO2 in the
presence of various amounts of Fe3O4/HT-IM (V) nanocatalyst at 100
°C and 0.7 MPa for 8 h.
The chemical fixation reactions of the other epoxides with carbon
dioxide were studied after achieving optimized reaction conditions
in order for the substrate scope of the present dual catalyst system
to be examined (Scheme 2). The results were mentioned in Table 4.
It is obvious that the catalyst system was proved to be practical and
appropriate for a variety of epoxides. Moreover, it is noteworthy that
without any side products, this system formed the corresponding
cyclic carbonates in good to excellent yields and also all reactions
proceeded efficiently. As can be seen, transferring to the
corresponding cyclic carbonate can be quantitatively done when
aromatic epoxide was used in very high yields (96 %) (Table 4, entry
1). In addition, when the aliphatic epoxides were incorporated with
both electron-donating and electron-withdrawing groups (Table 4,
entries 2-6), a high yield around 95-97 % was achieved. It is
O
O
O
O
O
O
4
6
97
Br
Br
O
O
O
O
5
9
95
O
O
O
O
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View Article Online
DOI: 10.1039/D0NJ05225F
O
O
O
O
O
6
7
96
O
6
7
8
9
Cl
Cl
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60
O
7
8
6
98
60
O
O
Figure 13. FESEM image of (a) 6th reused Fe3O4/HT-IM (V)
nanocatalyst and EDX analysis of (b) 6th reused Fe3O4/HT-IM (V)
nanocatalyst.
O
O
To evaluate the heterogeneous nature of the nanocatalyst, a hot
filtration test was carried out. The model reaction was firstly done
under the optimized reaction condition (for 4 h). Then, the catalyst
was magnetically separated from the reaction mixture, and it was
seen that the reaction proceeded approximately 40%. Next, the
reaction continued and has been monitored (by TLC) for another 4
hours without the presence of any catalyst. It is worth noting that no
further proceeding in the reaction was observed after removing the
catalyst. Hence, this clearly indicates that no leaching took place
during the reaction and it can be concluded that the nanocatalyst is
truly heterogeneous and it is stable during the catalytic reaction.
A recommended catalytic mechanism pathway for the chemical
fixation catalyzed by Fe3O4/HT-IM (V) nanocatalyst is shown in
Scheme 3. According to the literature,44 the epoxy ring was firstly
activated by the Lewis acid sites of nanocatalyst, which coordinated
to the O atom of the epoxide and caused the formation of
intermediate (I). In the following step, a ring opening of the epoxide
took place by the nucleophilic attack of Br- anion, which led to the
formation of intermediate (II). Then, the nucleophilicity attack of
oxygen atom of intermediate (II) happened to capture CO2, forming
the corresponding intermediate (III), which was followed by the
removal of Br- anion, and simultaneously eventually afforded the
corresponding cyclic carbonate (IV). Finally, the nanocatalyst was
released from the product and the catalytic cycle was completed.
O
O
O
10
O
Considering that the reusability of a catalyst is one of the most
significant merits of heterogeneous nanocatalysts, the reusability of
the Fe3O4/HT-IM nanocatalyst was also studied under optimized
experimental conditions. In this experiment, after the completion of
the reaction, the nanocatalyst was easily recovered using an external
magnetic field and was subsequently washed with ethylacetate and
distilled water. Next, it was dried in a vacuum oven and reused for
performing the reaction for 6 times without any considerable loss in
the level of activity and selectivity. The results are shown in Figure
12.
R
Fe
3O4/HT-IM
Fe
3O4/HT-IM
O
O
O
O
(IV)
R
R
(I)
Br
Br
Figure 12. The reusability of the Fe3O4/HT-IM (V) nanocatalyst in the
coupling reaction of styrene oxide and CO2 under the optimized
reaction conditions.
Fe
3O4/HT-IM
O
O
C
O
Br
R
O
It is worth mentioning that a comparison of the FESEM and EDX
images of the fresh Fe3O4/HT-IM (V) nanocatalyst (Figure 5b and 5d)
and after 6 times of using (Figure 13a and 13b) proved that the
morphology did not change considerably, revealing the chemical
stability of the synthesized Fe3O4/HT-IM (V) nanocatalyst.
(II)
Br
R
(III)
CO2
Scheme 3. Recommended mechanism pathway for the preparation
of cyclic carbonate derivatives using Fe3O4/HT-IM (V) nanocatalyst.
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In this line of work, to prove the merits and catalytic efficiency of the
Experimental
Material characterizations
View Article Online
DOI: 10.1039/D0NJ05225F
presented catalytic system for model reaction compared to some of
the previously reported procedures that have been recently
published in the literature, a comparative study was carried out, and
the obtained results are listed in Table 5. In spite of the fact that each
of these procedures has their own merits, some of them suffer from
using toxic solvent (Table 5, entry 1, 2) or additive (co-catalyst/ base)
(Table 5, entries 3-12) to achieve the desired product, which can be
removed by using this introduced catalytic system. More
importantly, our presented catalyst system is superior to the other
related reported catalytic systems thanks to its easy separation and
reusability using an external magnet (Table 5, entries 13-17).
All chemical reagents and solvents were purchased from Merck and
Sigma-Aldrich chemical companies and were used as received
without further purification. The purity determinations of the
products were accomplished by TLC on silica gel polygram STL G/UV
254 plates. The FT-IR spectra were obtained using an AVATAR 370 FT-
IR spectrometer (Therma Nicolet spectrometer, USA). The NMR
spectra were obtained in Brucker AMX 300 MHz instruments in
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59
60
CDCl3. TGA analysis was carried out on
a
Shimadzu
Thermogravimetric Analyzer (TG-50) in the temperature range of 25-
900 °C at a heating rate of 10 °C min-1 under air atmosphere. The
crystalline structure of samples are analyzed using a Bruker (D8
Advance, Germany) powder X-ray diffraction (PXRD) apparatus
working with Cu Kɑ radiation oprerated at 40 kV and 40 mA. The
catalyst were analyzed in a step scan mode, using a step size rating
of 0.02°/s in the 2Ɵ range of 10-80°. The morphology of synthesized
sampled was investigated with field-emission scanning electron
microscopy (FESEM) using a HITACHI S-4160 instrument. In addition,
the elemental analysis of samples is conducted using energy
dispersive X-ray spectroscopy (EDS). Transmission electron
microscopy (TEM) was applied to investigate the structure of
synthesized nanocatalyst using a JEOL, JEM-2100F, 200 KV
instrument. TPD experiments were carried out using a NanoSORD
NS91 apparatus equipped with a TCD detector which detects the
concentration in the gas stream and the adsorbed amount is
calculated from the concentration change. H2-Temperature
Programmed Reduction (H2-TPR) experiment were carried out using
a NanoSORD NS91 apparatus. The zeta potential of both the samples
was analyzed using the HORIBA SZ-100 nanoPartica system. All the
yields refer to isolated products after purification by column
chromatography.
Table 5. Comparison between efficiency of Fe3O4/HT-IM (V)
nanocatalyst and some other catalysts for the synthesis of
1,3-dioxolan-2-one.
Entry
1
Reaction conditions
Time (h)
24-48
Yield (%)
67-92
Ref.
22
LDH, DMF, 100 °C, 0.1 MPa
Mg-Al mixed oxide, DMF, 100 °C,
0.5 MPa
21
2
15
29-90
Multifunctional MOFs, TBAB, 70
°C, 0.1 MPa
45
46
47
3
4
5
12
48
73-99
71-99
55-98
COF-JLU7, TBAB, 40 °C, 0.1 MPa
MTpFPC, TBAB, 25-60 °C, 0.1
MPa
8-20
ZnO@NPC-Ox-700, TBAB, CH3CN,
60 °C. 0.1 MPa
48
49
49
6
7
8
48
48
85-95
61-80
33-99
Cu-MOG, TBAB, rt, 0.1 MPa
Ti-PCP, TBAB,DMF, 100 °C, 0.1-6
MPa
4-24
Preparation of HT (I), Fe3O4/HT (II) and Fe3O4/HT-(CH2)3-Cl (III)
Cationic Zinc-Organic
Framework, nBu4NBr, 80 °C, 0.1
MPa
HT (I), Fe3O4/HT (II) and Fe3O4/HT-(CH2)3-Cl (III) were synthesized
according to the procedure reported in literature.20 Briefly, in a
typical reaction, following a similar procedure, a mixed solution (60
mL) containing NaOH (4 g, 100 mmol) and NaHCO3 (2.1 g, 25 mmol)
was added drop by drop to 60 mL mixed salt solution (molar ratio
Mg/Al : 2/1) with a vigorously-stirring bar and it was heated till 60 °C
for 24 h. After this time, the obtained white residue (HT) was filtered
and washed three times with water and dried at 100 °C for 12 h. After
that, a solution (100 mL) of FeCl3.6H2O (2.1 g, 8 mmol) and
FeCl2.4H2O (1.05 g, 5.2 mmol) was placed in a three-necked 500 mL
round-bottom flask equipped with argon gas inlet tube and heated
at 80 °C under Ar flow for minutes. Then, 4 g of HT (I) powder and
100 mL NaOH solution (5%) were simultaneously poured in the metal
solution and carried out at 80 °C for 24 h. After the reaction was
completed, using an external magnet the obtained brown powder
was collected and rinsed with distilled water (2 × 100 mL) to give
Fe3O4/HT (II). Then, functionalization of Fe3O4/HT (II) was carried
out by treating dispersed Fe3O4/HT (II) (2 g in toluene) with 3-
Chloropropyltrimethoxysilane (2 g, 8 mmol) under 12 h reflux
condition. Successively, after cooling to room temperature, the
resultant precipitate was washed with ethanol (20 mL), and dried at
50 °C.
50
51
9
1
51-99
49-99
hydroxy-containing imidazole
organocatalysts, Bu4NX, 90 °C,
0.1-1 MPa
10
2-6
52
53
16
17
54
11
12
13
14
15
NIS, DBU, 60 °C, 0.1 MPa
[PS-Zn(II)L], Bu4NBr, rt, 0.1 MPa
MgO, Bu4NBr, rt, 0.1 MPa
12
8
37-99
94-100
42-92
76-91
38-93
1-8
8
UiO-66/Cu-BTC, 60 °C , 1.2 MPa
FJI-C10, 60-80 °C, 0.1 MPa
12-48
[TMGH+][O2MMIm+][Br-], 30 °C, 1
MPa
55
56
16
17
18
12
30
8
94-99
5-95
96
Bifunctional aluminum salen
complex, 80 °C, 2 MPa
This
Fe3O4/HT-IM, 100 °C, 0.7 MPa
work
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Preparation of Fe3O4/HT-(CH2)3-Melamine (IV)
other organic transformation in industrial scaleVtieowwAartircdlesOntlhinee
green chemistry in the future.
DOI: 10.1039/D0NJ05225F
Typically, Fe3O4/HT-(CH2)3-Cl (III) (0.5 g) and 4 g of melamine were
dispersed in 50 mL ethanol. After mixing them together, a solution of
NaOH (1 M) was added while being vigorously stirred, refluxed and
maintained for 48 h. After that, the solid magnetic residue was
collected by an external magnet and washed three times with hot
water (200 mL), and dried at 80 °C for 3h.
Conflicts of interest
There are no conflicts to declare.
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Preparation of Fe3O4/HT-IM (V) nanocatalyst
Acknowledgements
We gratefully acknowledge the support of this work by the
Shiraz University of Technology Research Council.
Fe3O4/HT-(CH2)3-Melamine (IV) (0.25 g), K2CO3 (0.25 g) and 1,6-
dibromo hexane (1 mL) were poured into a round bottom flask
equipped with a magnetic stirrer, and were stirred and heated at 100
°C for 12 h. After that, the final residue was magnetically collected
and then washed three times with hexane (100 mL), H2O (100 mL)
and ethanol (100 mL), respectively, and dried at oven (50 °C). At the
next step, the final residue (0.25 g) was added to K2CO3 (0.25 g) and
1-methyl imidazole (1 mL) and stirred continuously at 100 °C for 12
h. At that time, Fe3O4/HT-IM (V) as the final nanocatalyst was also
washed (with methanol/H2O 50/50), and placed in the oven at 50 °C.
Notes and references
1.
2.
3.
4.
5.
6.
7.
8.
T. Sakakura, J.-C. Choi and H. Yasuda, Chem. Rev., 2007,
107, 2365-2387.
L. Wang, G. Zhang, K. Kodama and T. Hirose, Green Chem.,
2016, 18, 1229-1233.
A. Hafizi, M. Mokari, R. Khalifeh, M. Farsi and M.
Rahimpour, J. Mol. Liq., 2020, 297, 111803.
A. Hafizi, M. Rajabzadeh and R. Khalifeh, J. Environ. Chem.
Eng., 2020, 8, 103845.
L. C. Yang, Z. Q. Rong, Y. N. Wang, Z. Y. Tan, M. Wang and
Y. Zhao, Angew. Chem. Int. Ed., 2017, 56, 2927-2931.
J. P. Vivek, N. Berry, G. Papageorgiou, R. J. Nichols and L. J.
Hardwick, J. Am. Chem. Soc., 2016, 138, 3745-3751.
S. Verma, G. Kumar, A. Ansari, R. I. Kureshy and H. K. Noor-
ul, Sustain. Energy Fuels, 2017, 1, 1620-1629.
H. Büttner, C. Kohrt, C. Wulf, B. Schäffner, K. Groenke, Y.
Hu, D. Kruse and T. Werner, ChemSusChem, 2019, 12,
2701-2707.
Representative procedure for the chemical fixation of CO2 with
epoxides in the presence of Fe3O4/HT-IM (V) nanocatalyst
The cycloaddition reaction of epoxides with carbon dioxide was
carried out at a stainless steel high-pressure batch reactor equipped
with a magnetic stirrer. Then, epoxide (3 mmol) and the Fe3O4/HT-
IM (V) nanocatalyst (1.6 mol%) were added into the reactor at 0.7
MPa pressure. Subsequently, the mixture was heated for the
indicated time at 100 °C. Upon completion, the reactor has been
cooled to reach ambient temperature which led to slow release of
CO2 from the vessel. After this, the extraction of the mixture reaction
was conducted using ethyl acetate (3 × 10 mL), and the catalyst was
readily separated by an external magnetic field. Finally, the
concentration and purification of the organic layer was done using
column chromatography by eluent ethylacetate and n-hexane (2:1).
9.
Q.-W. Song, Z.-H. Zhou and L.-N. He, Green Chem., 2017,
19, 3707-3728.
Y. M. Shen, W. L. Duan and M. Shi, Eur. J. Org. Chem., 2004,
2004, 3080-3089.
10.
11.
12.
13.
Q.-W. Song, B. Yu, X.-D. Li, R. Ma, Z.-F. Diao, R.-G. Li, W. Li
and L.-N. He, Green Chem., 2014, 16, 1633-1638.
R. Babu, A. C. Kathalikkattil, R. Roshan, J. Tharun, D.-W.
Kim and D.-W. Park, Green Chem., 2016, 18, 232-242.
M. Bahadori, S. Tangestaninejad, M. Bertmer, M.
Moghadam, V. Mirkhani, I. Mohammadpoor− Baltork, R.
Kardanpour and F. Zadehahmadi, ACS Sustain. Chem. Eng.,
2019, 7, 3962-3973.
Conclusions
In conclusion, we have successfully synthesized and employed
a stable, environmentally benign and plate-like Fe3O4/HT-IM
nanocatalyst that can efficiently tolerate reaction of a diverse
range of epoxides with CO2 under green reaction conditions
with excellent-to-high yield. It is noticeable that this catalytic
system is not sensitive to air and minor moisture. The
importance of the synthesized Fe3O4/HT-IM nanocatalysts with
other catalysts and also the reaction plausible mechanism has
been revealed in this paper. Although, to further clarify the
mechanism of this reaction in detail, efforts are now in progress.
Especially, this catalytic system can be easily recovered upon
release of CO2 and reused for six consecutive cycles without
obvious loss of activity and selectivity. Importantly, this
described nanocatalyst is also unique as it consists both acid and
base sites which promotes the cycloaddition reaction of CO2
which is an advantageous point of the presented methodology.
It is expected that these characteristics make the proposed
protocol an ideal catalyst system that is suitable for the
synthesis of a wide range of valuable chemical materials and
14.
15.
16.
17.
18.
19.
20.
21.
22.
X. Zhang, N. Zhao, W. Wei and Y. Sun, Catal. Today, 2006,
115, 102-106.
A. Farhadian, M. B. Gol Afshani, A. Babaei Miyardan, M. R.
Nabid and N. Safari, ChemistrySelect, 2017, 2, 1431-1435.
A. H. Chowdhury, P. Bhanja, N. Salam, A. Bhaumik and S.
M. Islam, Mol. Catal., 2018, 450, 46-54.
J. F. Kurisingal, Y. Rachuri, Y. Gu, G.-H. Kim and D.-W. Park,
Appl. Catal. A., 2019, 571, 1-11.
M. Sengupta, A. Bag, S. Ghosh, P. Mondal, A. Bordoloi and
S. M. Islam, J. CO2 Util., 2019, 34, 533-542.
Y. Chen, P. Xu, M. Arai and J. Sun, Adv. Synth. Catal., 2019,
361, 335-344.
Z. Zarei and B. Akhlaghinia, New J. Chem., 2017, 41, 15485-
15500.
H. Kawanami and Y. Ikushima, Chem. Commun., 2000,
2089-2090.
Y. Kuwahara and H. Yamashita, J. CO2 Util., 2013, 1, 50-59.
10 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 11 of 12
New Journal of Chemistry
Please do not adjust margins
Journal Name
ARTICLE
1
2
3
4
5
6
7
8
9
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
S. Das, F. D. Bobbink, S. Bulut, M. Soudani and P. J. Dyson, 53.
Chem. Commun., 2016, 52, 2497-2500.
J. Peng, S. Wang, H.-J. Yang, B. Ban, Z. Wei, L. Wang and L. 54.
Bo, Catal. Today, 2019, 330, 76-84.
X. Xiong, H. Zhang, S. L. Lai, J. Gao and L. Gao, React. Funct. 55.
Polym., 2020, 149, 104502.
T. Wang, Y. Ma, J. Jiang, X. Zhu, B. Fan, G. Yu, N. Li, S. Wang, 56.
T. Ren and L. Wang, J. Mol. Liq., 2019, 293, 111479.
S. Hosseini, G. Moradi and K. Bahrami, Renew. Energy,
2019, 138, 70-78.
F. Rezaei, R. Khalifeh and M. Amrollahi, Mater. Today
Chem., 2020, 18, 100353.
R. Khalifeh and A. Niknam, Org. Prep. Proced. Int., 2020, 52,
91-98.
F. Rezaei, M. A. Amrollahi and R. Khalifeh, ChemistrySelect,
2020, 5, 1760-1766.
R. Khalifeh, M. Rajabzadeh and A. Ebadi, ChemistrySelect,
2019, 4, 13089-13093.
A. Ebadi, M. Rajabzadeh and R. Khalifeh, ChemistrySelect,
2019, 4, 7211-7218.
M. Rajabzadeh, R. Khalifeh, H. Eshghi and M. Sorouri, Catal.
Lett., 2019, 149, 1125-1134.
F. Rezaei, M. A. Amrollahi and R. Khalifeh, Inorg. Chim.
Acta, 2019, 489, 8-18.
R. Khalifeh and F. Karimzadeh, Can. J. Chem., 2019, 97, 303-
309.
R. Khalifeh, R. Shahimoridi and M. Rajabzadeh, Catal. Lett.,
2019, 149, 2864-2872.
M. Rajabzadeh, R. Khalifeh, H. Eshghi and M. Bakavoli, J.
Catal., 2018, 360, 261-269.
M. Rajabzadeh, H. Eshghi, R. Khalifeh and M. Bakavoli,
Appl. Organomet. Chem., 2018, 32, e4052.
M. Rajabzadeh, H. Eshghi, R. Khalifeh and M. Bakavoli,
Appl. Organomet. Chem., 2017, 31, e3647.
R. Khalifeh and M. Ghamari, J. Braz. Chem. Soc., 2016, 27,
759-768.
S. Biswas, R. Khatun, M. Sengupta and S. M. Islam, Mol.
View Article Online
Catal., 2018, 452, 129-137.
DOI: 10.1039/D0NJ05225F
J. Liang, Y.-Q. Xie, X.-S. Wang, Q. Wang, T.-T. Liu, Y.-B.
Huang and R. Cao, Chem. Commun., 2018, 54, 342-345.
J. Hu, J. Ma, H. Liu, Q. Qian, C. Xie and B. Han, Green Chem.,
2018, 20, 2990-2994.
R. Luo, Z. Yang, W. Zhang, X. Zhou and H. Ji, Sci. China
Chem., 2017, 60, 979-989.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
M. Rajabzadeh, H. Eshghi, R. Khalifeh and M. Bakavoli, RSC
Adv., 2016, 6, 19331-19340.
W. Jozwiak, E. Kaczmarek, T. Maniecki, W. Ignaczak and W.
Maniukiewicz, Appl. Catal. A., 2007, 326, 17-27.
R. Ibrahim and Y. Lwin, J. Appl. Sci., 2010, 10, 1128-1133.
S. Liu, N. Suematsu, K. Maruoka and S. Shirakawa, Green
Chem., 2016, 18, 4611-4615.
C.-S. Cao, Y. Shi, H. Xu and B. Zhao, Dalton Trans., 2018, 47,
4545-4553.
Y. Zhi, P. Shao, X. Feng, H. Xia, Y. Zhang, Z. Shi, Y. Mu and X.
Liu, J. Mater. Chem. A, 2018, 6, 374-382.
M. Tiffner, S. Gonglach, M. Haas, W. Schöfberger and M.
Waser, Chem. Asian J., 2017, 12, 1048-1051.
M. Ding, S. Chen, X. Q. Liu, L. B. Sun, J. Lu and H. L. Jiang,
ChemSusChem, 2017, 10, 1898-1903.
43.
44.
45.
46.
47.
48.
49.
50.
51.
C. K. Karan, M. C. Sau and M. Bhattacharjee, Chem.
Commun., 2017, 53, 1526-1529.
C. Yao, S. Zhou, X. Kang, Y. Zhao, R. Yan, Y. Zhang and L.
Wen, Inorg. Chem., 2018, 57, 11157-11164.
J. A. Castro-Osma, J. Martínez, F. de la Cruz-Martínez, M. P.
Caballero, J. Fernández-Baeza, J. Rodríguez-López, A.
Otero, A. Lara-Sánchez and J. Tejeda, Catal. Sci. Technol.,
2018, 8, 1981-1987.
52.
R. Ma, L.-N. He, X.-F. Liu, X. Liu and M.-Y. Wang, J. CO2 Util.,
2017, 19, 28-32.
This journal is © The Royal Society of Chemistry 20xx
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DOI: 10.1039/D0NJ05225F
Graphical abstract
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Imidazolium-based ionic liquid immobilized on functionalized magnetic
hydrotalcite (Fe3O4/HT-IM): as an efficient heterogeneous magnetic
nanocatalyst for chemical fixation of carbon dioxide under green
conditions
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Fe3O4/HT-IM with plate-like morphology was synthesized as a novel and highly effective
magnetic nanocatalyst and applied in the chemical fixation.