Amine formylation with CO2 and H2 catalyzed by heterogeneous Pd/PAL catalyst

Article abstract of DOI:10.1016/S1872-2067(19)63397-8

For the first time, Pd supported on natural palygorskite was developed for amine formylation with CO₂ and H₂. Both secondary and primary amines with diverse structures could be converted into the desired formamides at < 100 °C, and good to excellent yields were obtained.

Full text of DOI:10.1016/S1872-2067(19)63397-8

Chinese Journal of Catalysis 40 (2019) 1141–1146
a v a i l a b l e a t w w w . s c i e n c e d i r e c t . c o m
j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / c h n j c
Communication
Amine formylation with CO2 and H2 catalyzed by heterogeneous
Pd/PAL catalyst
Xingchao Dai a,d, Bin Wang b, Aiqin Wang c, Feng Shi a,*
a State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000,
Gansu, China
b Key Laboratory for Utility of Environment-Friendly Composite Materials and Biomass in University of Gansu Province, College of Chemical Engineering,
Northwest Minzu University, Lanzhou 730030, Gansu, China
c Key Laboratory of Clay Mineral Applied Research of Gansu Province, Center of Eco-materials and Green Chemistry, Lanzhou Institute of Chemical Physics,
Chinese Academy of Sciences, Lanzhou 730000, Gansu, China
d University of Chinese Academy of Sciences, Beijing 100049, China
A R T I C L E I N F O
A B S T R A C T
Article history:
For the first time, Pd supported on natural palygorskite was developed for amine formylation with
CO2 and H2. Both secondary and primary amines with diverse structures could be converted into the
desired formamides at < 100 °C, and good to excellent yields were obtained.
© 2019, Dalian Institute of Chemical Physics, Chinese Academy of Sciences.
Published by Elsevier B.V. All rights reserved.
Received 25 March 2019
Accepted 8 May 2019
Published 5 August 2019
Keywords:
Formylation
Carbon dioxide
Amine
Heterogeneous palladium catalyst
Formamide
CO2 emission reduction and resource utilization are one of
the major challenges in the 21st century due to an energy crisis
in the foreseeable future and increasing environmental pres-
sure [1]. As an economic, safe, and sustainable C1 resource, the
transformation of CO2 to high value-added products through
modern technology has attracted significant attention [2–9].
However, the highly symmetrical molecular structure of CO2
and the high oxidation state of the carbon atom are responsible
for its extremely stable chemical properties, making the activa-
tion and conversion of CO2 difficult under mild conditions.
Typically, the conversion of CO2 involves three steps: adsorp-
tion, activation, and directed transformation. Therefore, an
ideal catalytic material for CO2 transformation should exhibit
multifunctional characteristics and be able to adsorb, activate,
and selectively convert CO2 to the desired product. Introducing
an organic ligand containing active elements is a common
means of achieving the transformation [3]. By targeted interac-
tion with the active metal center [10–16], the ligand could sup-
press or increase the ability of the active metal center in certain
aspects to finally achieve the accurate mediation of the catalytic
performance. Although good results have been achieved by the
above methods, the high cost and complicated synthetic pro-
* Corresponding author. Tel: +86-931-4968142; Fax: +86-931-8277088; E-mail: fshi@licp.cas.cn
This work was supported by the National Natural Science Foundation of China (91745106, 21633013), the Major Projects of the National Natural
Science Foundation of Gansu, China(18JR4RA001), the Youth Innovation Promotion Association CAS (2019409), Fujian Institute of Innovation, CAS
and Key Research Program of Frontier Sciences of CAS (QYZDJ-SSW-SLH051).
DOI: S1872-2067(19)63397-8 | http://www.sciencedirect.com/science/journal/18722067 | Chin. J. Catal., Vol. 40, No. 8, August 2019

1142
Xingchao Dai et al. / Chinese Journal of Catalysis 40 (2019) 1141–1146
cesses of the organic ligands are undesirable from the stand-
point of industrial application. Therefore, exploring new multi-
functional materials with excellent catalytic performances in
CO2 resource utilization is important.
Initially, a series of supported Pd-based catalysts with dif-
ferent supports were prepared by the reductive deposition
method, in which the metal Pd was reduced and deposited on
or in the PAL support with H2PdCl4 as a metal precursor and
hydrazine hydrate as the reducing agent (see Supporting In-
formation). The catalysts were characterized by different ana-
lytical techniques and tested for formamide synthesis by the
reaction of piperidine with CO2 and H2 (Table 1). Obviously,
PAL was better as a catalyst support than other inorganic ox-
ides (entries 1–8), and 24% yield of piperidine-1-carbaldehyde
was obtained in the presence of Pd/PAL catalyst (entry 1).
Considering the unique structure and cation exchange capacity
of PAL, we speculated that the excellent catalytic performance
of the Pd/PAL catalyst might have originated from the syner-
gistic effect of the intrinsic acid and basic sites in the PAL sup-
port and the metal Pd species inside the PAL support. Basically,
the introduction of Pd species inside the PAL support might be
favorable for the formation of the desired formamide. To verify
the assumption, a Pd/PAL-12 catalyst was prepared by ex-
tending the ion exchanging time to 12 h. As expected, the
Pd/PAL-12 catalyst exhibited excellent catalytic performance
and the formamide yield was increased to 35% (entry 9). Sub-
sequently, the effect of base additives was studied, and differ-
ent bases such as KOH, NaOH, K2CO3, Na2CO3, and NaF were
tested and their effects were compared (Entries 10–14). Con-
sequently, K2CO3 was proven to be the most suitable base and
60% yield of piperidine-1-carbaldehyde could be obtained by
introducing 50 mol% K2CO3 (entry 12). Relatively low yields
were observed for other bases (entries 10, 11, and 13). By ex-
tending the reaction time to 24 h, the yield of piperi-
Pd has been proven to be active in the reductive formylation
of CO2 with H2 as the reducing agent [17–25], and two exam-
ples of homogeneous catalytic systems [24,25] and seven ex-
amples of heterogeneous versions [17–23] have been reported
thus far. In these systems, good product yields were obtained
when aliphatic secondary amines were used as the starting
materials, while only low to moderate product yields were ob-
tained in the case of aliphatic primary amines [22,23]. Recently,
Liu and Han et al. [17–19] showed that Mg-Al layered double
hydroxide (Mg-Al LDH) and N-doped carbon (NC) supported
Pd (Pd/LDH and Pd/NC) as well as mesoporous imine-based
organic polymer coordinated Pd (Imine-POP@Pd) were active
for the amine formylation with CO2 and H2, although a high
reaction temperature (140 °C) and/or CO2 pressure (3 MPa), as
well as high Pd loading (8.1 wt%) were required. Based on the
continuous efforts focused on the transformation of CO2
[26,27], our group [20] demonstrated that the hydroxyl
group-regulated nano-Pd/C catalyst could catalyze the
N-formylation of amines with CO2 and H2, although the reaction
conditions were still relatively harsh and the procedure for
preparing the carbon support was complicated. Therefore, de-
veloping a general heterogeneous catalyst for the amine
formylation with CO2 and H2 is still of significance.
Palygorskite (PAL), also known as attapulgite (APT), is a
naturally available, one-dimensional nanoscale hydrated mag-
nesium aluminum silicate clay mineral with abundant zeo-
lite-like channels, a high surface area, and moderate cation
exchange capacity [28]. Besides, PAL possesses multiple types
of acid and basic active sites due to the existence of interlayer
water molecules, surface adsorbed oxygen, and hydroxyl
groups, as well as some cations, such as Si, Al, and Mg. There-
fore, PAL could provide a reaction environment containing
multiple functional sites and be a promising catalyst support
candidate for the preparation of multifunctional catalytic mate-
rials. Herein, we present the first example of PAL supported
heterogeneous Pd catalysts for the general and efficient amine
formylation with CO2 and H2, under mild reaction conditions
(Fig. 1). Both secondary and primary amines can be converted
into the corresponding formamides with good to excellent
yields, at < 100 °C with 1 MPa CO2.
Table 1
Catalyst screening and reaction condition optimizationa.
Entry
1
2
3
4
5
6
7
8
Catalyst
Pd/PAL
Pd/Al2O3
Pd/SiO2
Solvent
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
Base
—
—
—
—
—
—
—
—
t/h Yield b (%)
5
5
5
5
5
5
5
5
5
5
5
5
5
5
24
15
14
22
15
15
5
22
35
47
24
60
51
35
90
—
—
26
Pd/MgO
Pd/MgAlOx
Pd/MgSiOx
Pd/AlSiOx
Pd/MgAlSiOx
Pd/PAL-12
Pd/PAL-12
Pd/PAL-12
Pd/PAL-12
Pd/PAL-12
Pd/PAL-12
Pd/PAL-12
PAL
9
—
10
11
12
13
14
15
16
17 c
18 d
KOH
NaOH
K2CO3
NaCO3
NaF
K2CO3 24
K2CO3
K2CO3
K2CO3
5
5
5
Pd0
Pd/C
a Reaction conditions: 1 mmol piperidine, 100 mg catalyst, 3 MPa H2, 1
MPa CO2, 50 mol% base, 3 mL solvent, 96 °C (reaction temperature).
b
Yields were determined by GC-FID with biphenyl as an external stand-
c
ard. Pd0 (0.38 mg, prepared by the same procedure used for the
Pd/PAL catalyst) was used as the catalyst. d Commercial 5 wt% Pd/C (8
mg, obtained from Lanzhou Zhongke Kaidi Chemical New Technology
Co., Ltd.) was used as the catalyst.
Fig. 1. N-formylation of amine with CO2 and H2 catalyzed by Pd/PAL
catalyst via the synergistic effect of multiple functional sites.

Xingchao Dai et al. / Chinese Journal of Catalysis 40 (2019) 1141–1146
1143
.Pd0 [01-1201]
Table 2
.
.
Properties of the prepared catalysts.
Pd a
SA b
PV c
APR d
(nm)
Entry
Catalyst
(wt%) (m2 g‒1
)
(10‒2/cm3 g‒1
)
.
.
1
2
3
4
5
6
7
8
9
Pd/PAL-12
Pd/PAL
0.38
0.33
0.36
0.34
0.38
0.40
0.37
0.39
0.35
149
171
31
144
414
174
245
24
62.2
69.1
12.8
42.2
97.3
43.9
17.6
2.5
8.4
8.1
8.2
5.9
4.7
5.1
1.4
2.1
2.5
Pd/MgO
Pd/Al2O3
Pd/SiO2
Pd/MgAlOx
Pd/MgSiOx
Pd/AlSiOx
Pd/MgAlSiOx
.
.
44
5.6
a Determined by ICP-AES. b BET surface area. c Total pore volume. d Av-
erage pore radius.
20
40
60
80
2/(o)
dine-1-carbaldehyde could be increased to 90% (entry 15). The
formamide product was not observed when the bare PAL sup-
port or metallic Pd0 was applied, which implied that the sup-
ported Pd0 was active for the N-formylation of amine with CO2
and H2 (entries 16 and 17). As a weak acidic gas, CO2 was easily
adsorbed on basic sites, while basic amine was easily adsorbed
on acid sites [29,30]. Considering the existence of multiple
functional acid and basic sites on and in the PAL, the support
might be mainly responsible for the adsorption of amine and
CO2. When commercial Pd/C was applied under identical reac-
tion conditions, a low yield of formamide was obtained (entry
18).
To explore the correlation between the structure and activ-
ity, the prepared catalysts were extensively characterized. The
N2 adsorption-desorption analysis revealed that the BET sur-
face area of the active Pd/PAL-12 catalyst was smaller than that
of Pd/PAL (Table 2, entries 1 and 2), which suggested that
more metal Pd migrated into the support, leading to the block-
age of some pores. The Pd/SiO2 catalyst had the largest BET
surface area (entry 5), and the smallest BET surface area was
obtained in the case of Pd/AlSiOx (entry 8). Notably, the active
catalyst, Pd/PAL-12, exhibited the highest average pore radius
(8.4 nm, Table 2, entry 1 and Fig. S1), suggesting that the large
pore size might be favorable for the formation of the desired
product. The Pd contents of the prepared catalysts were de-
termined by inductively coupled plasma atomic emission spec-
troscopy (ICP-AES) and it varied in the range of 0.33 wt%–0.40
wt% (Table 2).
Fig. 2. XRD diffraction patterns of the prepared catalysts. The catalyst
samples are Pd/PAL-12, Pd/PAL, Pd/SiO2, Pd/MgO, Pd/Al2O3,
Pd/MgAlOx, Pd/MgSiOx, Pd/AlSiOx, and Pd/MgAlSiOx in ascending order,
respectively.
of the used Pd/PAL-12 catalyst (Figs. S2s–t) and no obvious
differences were observed upon comparing the fresh and used
samples.
The surface properties of the catalysts were determined by
X-ray photoelectron energy spectroscopy (XPS). The deconvo-
lution of the Pd 3d spectrum for the Pd/PAL-12 catalyst re-
vealed two components with binding energies (BEs) at ap-
proximately 335.6 and 338 eV (Fig. 3), which were similar to
those for the metallic Pd [32]. The second component with a BE
of 338 eV could be ascribed to the peak for Mg KL3 auger,
which could be confirmed by comparing the XPS spectra of all
other Mg-containing catalysts (Fig. S3). In similarity to the case
with the Pd/PAL-12 catalyst, a typical metallic Pd BE could be
observed in the XPS spectra of other catalysts (Fig. S3). In other
words, Pd on the surface of all catalysts existed in its metallic
Pd0 form. Thus, it is difficult to explain the difference in catalyt-
ic performances only by the state of the surface Pd. The above
Pd 3d
Pd/PAL-12
Mg KL3
The powder X-ray diffraction (XRD) patterns are shown in
Fig. 2. Only the major reflections of the supports were observed
in the Pd/PAL-12, Pd/PAL, and Pd/SiO2 catalysts; no signal
indicative of the Pd species was observed, which suggested that
the Pd species might be highly dispersed or amorphous. Con-
trary to the above cases, an obvious diffraction peak at ~18°
was observed for all other catalysts, which could be attributed
to the formation of metallic Pd species [31]. The Pd particles
were not observed in the transmission electron microscopy
(TEM) and high resolution (HR)-TEM images of Pd/PAL-12,
which might be due to the low metal loading or the formation
of Pd species with very small size inside the support (Figs.
S2a–b). A similar phenomenon was observed in the TEM image
Pd0 3d5/2
5.25
342
340
338
Binding Energy (eV)
Fig. 3. XPS spectra of the Pd/PAL-12 catalyst.
336
334

1144
Xingchao Dai et al. / Chinese Journal of Catalysis 40 (2019) 1141–1146
Table 3
Table 4
The surface and bulk atomic ratio of the catalysts.
Results for N-formylation of different aminesa.
SPd/Mg
BPd/Mg
(10–3
20.73
18.00
1.36
—
SPd/Al
BPd/Al
SPd/Si
BPd/Si
Entry
1
Substrate
Product
Yield b (%)
90/85c/84d
Catalyst
(10–3
6.78
7.99
5.16
—
)
)
(10–3
43.83
73.75
—
)
(10–3
15.66
13.60
—
)
(10–3
7.17
9.62
—
)
(10–3
4.11
3.57
—
)
Pd/PAL-12
Pd/PAL
Pd/MgO
Pd/Al2O3
Pd/SiO2
Pd/MgAlOx
Pd/MgSiOx
Pd/AlSiOx
2
3
99
95
6.24
—
7.16
—
1.64
—
3.43
—
4.09
9.61
—
8.95
—
34.73
70.41
64.49
—
2.15
—
3.49
4.08
3.20
—
—
N
O
7.88
15.26
—
3.43
3.49
—
4
5
6
7
99
98
90
86
O
266.08
Pd/MgAlSiOx 37.23
S: The surface atomic ratio. B: The bulk atomic ratio.
6.41 534.50
speculation that some Pd might migrate into the support, might
be the reason for the relatively high activity with PAL as sup-
port. Therefore, the amount of Pd in the support was evaluated
by comparing the surface and bulk Pd/M (M = Mg, Al or Si)
ratio of the catalysts (Table 3). Noticeably, the surface Pd/Mg
ratio in the Pd/PAL-12 catalyst was much lower than that in
the bulk, which meant that most of the Pd migrated into the
support. This is in good agreement with the results for N2 ad-
sorption-desorption analysis. A similar phenomenon was ob-
served for Pd/PAL, although it was found that the amount of Pd
inside the support should be less than that in the case of the
Pd/PAL-12 catalyst by comparing the two surfaces and bulk
Pd/Mg ratio, which might be the reason that the Pd/PAL cata-
lyst exhibited lower catalytic activity than that of the
Pd/PAL-12 catalyst. For the other Mg-containing catalysts such
as Pd/MgO, Pd/MgAlOx, Pd/MgSiOx, and Pd/MgAlSiOx, more Pd
species were observed in the supports.
Summarizing the above discussions, the excellent catalytic
performance of the Pd/PAL-12 catalyst could be attributed to
the relatively high amount of metal Pd that migrated into the
PAL support. The PAL support has a unique chain-layer struc-
ture and contains multiple acid and basic sites. If the metal Pd
migrates into the support, it can easily interact with more acid
and basic sites in comparison to the surface metal Pd. Moreo-
ver, the local environment consisting of multiple functional
sites, including metal Pd, acid, and basic sites provides favora-
ble reaction conditions for the adsorption and activation of
amine, CO2, and H2.
Next, the scope and limitations of the Pd/PAL-12 catalyst
were explored with the reaction of different amines and CO2/H2
(Table 4). Cyclic secondary amines could be converted into the
desired formamides in excellent yields. For example, 90%–99%
yields were obtained when piperidine and its derivatives were
used as the substrates (entries 1–3). Similar results were ob-
tained in the cases of morpholine, 1-methylpiperazine, and
pyrrolidine (entries 4–6). The Pd/PAL-12 catalyst is also active
for the reaction of normal secondary amine and CO2/H2. An
important industrial molecule, i.e., DMF, could be obtained in
86% yield when dimethylamine aqueous solution was used as
the starting material (entry 7). A nearly identical result was
obtained for dibutylamine (entry 8). The tolerance for
N-benzylethanamine was also good and could be converted
into the corresponding formamide in 83% yield (entry 9). Be-
8
9
85
83
10
11
12
88
96
83
95
13
14
88
15
16
76
81
86
NH2
17
18
78
90
19
a Reaction conditions: 1 mmol amines, Pd/PAL-12 (0.37 wt% Pd, 0.35
mol% Pd), 3 MPa H2, 1 MPa CO2, 3 mL MeOH, 96 °C (reaction tempera-
ture). b The product yields were determined by GC-FID with biphenyl as
an external standard. c The catalyst was used at the 2nd run. d The cata-
lyst was used at the 3rd run.
sides, primary amines with diverse structures also proved to be
active substrates and could easily react with CO2/H2 to synthe-
size the desired formamides. When butan-1-amine,
2-methylpropan-1-amine, butan-2-amine, and heptan-1-amine
were used as the substrates (entries 10–13), 83%–96% yields
were obtained. Cyclohexanamine and cyclopentanamine were
converted into the corresponding formamides in 88% and 76%
yields, respectively (entries 14 and 15). When benzylamine and
4-methyl-benzylamine were applied as the starting materials,
81-86% yields of the desired products were obtained (entries
16 and 17). Notably, good yield was obtained in the case of
1-phenylethanamine (entry 18). Typically, a 90% yield of the
corresponding
3-phenylpropan-1-amine reacted with CO2/H2 (entry 19).
formamide
was
obtained
when
Finally, the reusability of Pd/PAL-12 catalyst was tested for
the reaction of piperidine with CO2/H2 (Table 4, Entry 1). After
each reaction, the catalyst was recovered by simple centrifuga-
tion, washed, dried, and reused without further treatment. The
catalyst could be recycled for 3 runs without obvious deactiva-

Xingchao Dai et al. / Chinese Journal of Catalysis 40 (2019) 1141–1146
1145
Table 5
Comparison of the performances of the heterogeneous Pd catalysts reported in literature and in this study.
Entry
Catalyst
Pd/PAL-12
Pd/Al2O3-NR
Pd-Au/PANI-CNT
Pd/NC
Pd loading (wt%) CO2/H2 (MPa)
Base
K2CO3 50%
—
T/°C
96
130
125
130
100
t/h
24
24
48
24
24
Yield (%)
99
96
95.2
93
Ref.
This work
[23]
1
2
3
4
5
0.38
0.53
1.6
2
1/3
1/2
3.5/3.5
3/4
—
—
[22]
[19]
[17]
mine-POP-Pd
8.1
3/3
K3PO4 30%
97
tion and 84% product yield could be still maintained at the 3rd
run. Further Pd leaching test was performed to demonstrate
the stability and heterogeneity of the catalyst. After reacting for
5 h, the catalyst was removed, and the filtrate was analyzed by
ICP-AES. As a result, no Pd was detected in the filtrate and the
formamide product was not generated after removing the cat-
alyst, which further confirmed the stability of the catalyst dur-
ing the reaction and the supported Pd as the active species.
To assess our catalytic system, the catalytic performance of
the Pd/PAL-12 catalyst for the N-formylation of amine with CO2
and H2 was compared with that of the supported Pd-based
catalysts reported in the literature. Considering the wide use of
morpholine as a typical starting material, the N-formylation of
morpholine was used as the model reaction to evaluate the
catalytic performance of the different catalysts (Table 5). The
results showed that our catalyst system had the lowest Pd
loading and reaction temperature, but the highest yield of
formamide for the same reaction time, although a catalytic
amount of base was required, which confirmed that our cata-
lyst was more active.
To gain insights into the reaction mechanism, we traced the
reaction of piperidine and CO2 by GC-MS. The analysis results of
the reaction mixtures revealed the formation of methyl for-
mate. Based on the results and early reports [18], a possible
reaction mechanism was proposed. First, CO2 and H2 are ad-
sorbed and activated by the Pd/PAL catalyst, followed by the
reaction with methanol as the reaction medium to in situ gen-
erate HCOOCH3 intermediate with the aid of K2CO3. Subse-
quently, the generated HCOOCH3 reacts with piperidine to form
the targeted product.
In summary, a general and efficient supported Pd catalyst
was developed for amine formylation with CO2 and H2. The
catalyst was prepared by a simple reductive deposition method
with the natural palygorskite containing multiple functional
sites as support. Utilizing this catalyst, N-formylation of a series
of secondary and primary amines with CO2 and H2 could be
performed under mild conditions and good to excellent yields
were obtained. The analysis by a combination of characteriza-
tion techniques revealed that most of the Pd in the active
Pd/PAL-12 catalyst migrated into the PAL support, and the
interaction of Pd and acid/basic sites inside the support was
the key to synthesizing the desired formamides. The study of
the reaction mechanism revealed that the amine formylation
might proceed via methyl formate intermediate pathway.
References
[1] E. V. Kondratenko, G. Mul, J. Baltrusaitis, G. O. Larrazábal, J. Pé-
rez-Ramírez, Energy Environ. Sci., 2013, 6, 3112–3135.
[2] A. Tlili, E. Blondiaux, X. Frogneux, T. Cantat, Green Chem., 2015, 17,
157–168.
[3] K. Dong, R. Razzaq, Y. Hu, K. Ding, Top. Curr. Chem., 2017, 375, 23.
[4] W. Wan, B. M. Tackett, J. G. Chen, Chem. Soc. Rev., 2017, 46,
1807–1823.
[5] Y. Zhang, X. Dai, H. Wang, F. Shi, Acta Phys.-Chim. Sin., 2018, 34,
845–857.
[6] F. Shi, X. Cui, Catalytic Amination for N-Alkyl Amine Synthesis, Aca-
demic Press, Cambridge, 2018.
[7] G. Yuan, C. Qi, W. Wu, H. Jiang, Curr. Opin. Green Sustain. Chem.,
Graphical Abstract
Chin. J. Catal., 2019, 40: 1141–1146 doi: S1872-2067(19)63397-8
Amine formylation with CO2 and H2 catalyzed by heterogeneous
Pd/PAL catalyst
Xingchao Dai, Bin Wang, Aiqin Wang, Feng Shi*
Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences; North-
west Minzu University; University of Chinese Academy of Sciences
Heterogeneous Pd catalyst with the natural palygorskite as support could
effectively catalyze amine formylation with CO2 and H2 via the synergistic
effect of multiple functional sites.

1146
Xingchao Dai et al. / Chinese Journal of Catalysis 40 (2019) 1141–1146
2017, 3, 22–27.
[20] Y. Zhang, H. Wang, H. Yuan, F. Shi, ACS Sustain. Chem. Eng., 2017, 5,
5758–5765.
[21] R. A. Molla, P. Bhanja, K. Ghosh, S. S. Islam, A. Bhaumik, S. M. Islam,
ChemCatChem, 2017, 9, 1939–1946.
[22] P. Ju, J. Chen, A. Chen, L. Chen, Y. Yu, ACS Sustain. Chem. Eng., 2017,
5, 2516–2528.
[23] X. Cui, Y. Zhang, Y. Deng, F. Shi, Chem. Commun., 2014, 50,
189–191.
[24] Y. Morimoto, Y. Fujiwara, H. Taniguchi, Y. Hori, Y. Nagano, Tetra-
hedron Lett., 1986, 27, 1809–1810.
[25] K. Kudo, H. Phala, N. Sugita, Y. Takezaki, Chem. Lett., 1977, 6,
1495–1496.
[26] X. Cui, Y. Zhang, Y. Deng, F. Shi, Chem. Commun., 2014, 50,
13521–13524.
[27] X. Cui, X. Dai, Y. Zhang, Y. Deng, F. Shi, Chem. Sci., 2014, 5, 649–655.
[28] B. Mu, A. Wang, J. Environ. Chem. Eng., 2016, 4, 1274–1294.
[29] K. S. Walton, M. B. Abney, M. D. LeVan, Microporous Mesoporous
Mater., 2006, 91, 78–84.
[8] D. Zhang, J. Luo, J. Wang, X. Xiao, Y. Liu, W. Qi, D. S. Su, W. Chu, Chin.
J. Catal., 2018, 39, 157–166.
[9] J. Du, Y. Zhang, Y. Zhang, K. Wang, Q. Wang, J. Wu, J. Mol. Catal.
(China), 2016, 30, 346–353.
[10] R. Zhiani, S. M. Saadati, M. Zahedifar, S. M. Sadeghzadeh, Catal.
Lett., 2018, 148, 2487–2500.
[11] Y. Zhang, J. Wang, H. Zhu, T. Tu, Chem. Asian J., 2018, 13,
2956–2956.
[12] U. Jayarathne, N. Hazari, W. H. Bernskoetter, ACS Catal., 2018, 8,
1338–1345.
[13] H. Liu, Q. Mei, Q. Xu, J. Song, H. Liu, B. Han, Green Chem., 2017, 19,
196–201.
[14] P. Daw, S. Chakraborty, G. Leitus, Y. Diskin-Posner, Y. Ben-David, D.
Milstein, ACS Catal., 2017, 7, 2500–2504.
[15] M. A. Affan, P. G. Jessop, Inorg. Chem., 2017, 56, 7301–7305.
[16] L. Zhang, Z. Han, X. Zhao, Z. Wang, K. Ding, Angew. Chem. Int. Ed.,
2015, 54, 6186–6189.
[17] X. Yu, Z. Yang, S. Guo, Z. Liu, H. Zhang, B. Yu, Y. Zhao, Z. Liu, Chem.
Commun., 2018, 54, 7633–7636.
[30] T. Horiuchi, H. Hidaka, T. Fukui, Y. Kubo, M. Horio, K. Suzuki, T.
Mori, Appl. Catal. A, 1998, 167, 195–202.
[18] Y. Wang, B. Chen, S. Liu, X. Shen, S. Li, Y. Yang, H. Liu, B. Han,
ChemCatChem, 2018, 10, 5124–5127.
[31] J. D. Hanawalt, H. W. Rinn, L. K. Frevel, Ind. Eng. Chem. Anal. Ed.,
1938, 10, 475–512.
[19] X. Luo, H. Zhang, Z. Ke, C. Wu, S. Guo, Y. Wu, B. Yu, Z. Liu, Sci. China
Chem., 2018, 61, 725–731.
[32] R. T. Poole, P. C. Kemeny, J. Liesegang, J. G. Jenkin, R. C. G. Leckey, J.
Phys. F, 1973, 3, L46–L48.
Pd/PAL催化二氧化碳、氢气和胺反应合成甲酰胺
代兴超a,d, 王 斌b, 王爱勤c, 石 峰a,*
a中国科学院兰州化学物理研究所羰基合成与选择氧化国家重点实验室, 甘肃兰州730000
b西北民族大学化工学院甘肃省高校环境友好复合材料及生物质利用省级重点实验室, 甘肃兰州730030
c中国科学院兰州化学物理研究所环境材料与生态化学研究发展中心甘肃省粘土矿物应用研究重点实验室, 甘肃兰州730000
d中国科学院大学, 北京100049
摘要: CO2高效活化和定向转化合成高附加值化学品是催化化学领域的重要研究课题. 然而, 由于CO2分子具有高度对称结
构和高的碳原子氧化态, 其在温和条件下的活化和转化仍然是一个挑战. 众所周知, CO2的有效吸附和活化是其转化利用
的前提. 因此, 一种理想的CO2催化转化材料应该具有吸附、活化和选择性转化CO2的多功能特性. 据报道, 金属Pd能够催
化CO2/H2和胺反应合成甲酰胺. 但是已有的催化体系通常只对脂肪族仲胺显示出高的活性, 当脂肪族伯胺用作反应底物
时仅低到中等的产物收率. 最近, Liu和Han等报道负载型的Pd催化剂Imine-POP@Pd、Pd/LDH和Pd/NC能够催化CO2和脂肪
族伯胺反应合成甲酰胺. 但是这些催化体系要求高的反应温度(140 oC)、CO2压力(3 MPa)和Pd担载量(8.1 wt%). 我们小组
最近发现富羟基官能团碳担载的纳米Pd能够有效催化CO2/H2和胺反应合成甲酰胺, 但是反应条件仍然比较苛刻且碳载体
制备过程复杂.
凹凸棒石是一种天然的一维纳米水合镁铝硅酸盐粘土矿物, 不仅具有独特的链层状结构, 而且含有丰富的纳米孔道和
多种酸碱位点. 因此, 凹凸棒石有可能提供多种活性位点协同作用的反应环境, 用作CO2活化转化多功能催化材料合成的
潜在载体. 本论文首次以凹凸棒石为催化剂载体制备了负载型多相Pd/PAL催化剂, 并将其应用于CO2的还原胺化反应. 在
低于100 °C、1 MPa CO2条件下, 实现了一系列不同结构仲胺和伯胺到目标产物甲酰胺的转化, 并获得了较好的产物收率.
催化剂重复使用性研究结果表明, 催化剂Pd/PAL在反应过程中较为稳定. BET、XRD和XPS表征揭示, 部分负载的金属Pd
进入到了载体内部, 其与载体内部酸碱位点的协同作用可能是催化剂Pd/PAL能够高效催化CO2/H2和胺反应合成甲酰胺的
重要原因. 控制实验和反应机理研究表明, 甲酸甲酯是甲酰胺形成的可能中间体.
关键词: 甲酰化; 二氧化碳; 胺; 多相钯催化剂; 甲酰胺
收稿日期: 2019-03-25. 接受日期: 2019-05-08. 出版日期: 2019-08-05.
*通讯联系人. 电话: (0931)4968142; 传真: (0931)8277088; 电子信箱: fshi@licp.cas.cn
基金来源: 国家自然科学基金(91745106, 21633013); 甘肃省自然科学基金重大项目(18JR4RA001); 中国科学院青年创新促进会
(2019409); 中国科学院“西部之光”、中国科学院海西创新研究院和中国科学院前沿科学重点研究计划(QYZDJ-SSW-SLH051).
本文的电子版全文由Elsevier出版社在ScienceDirect上出版(http://www.sciencedirect.com/science/journal/18722067).