A novel and effective Zn/PEI-MCM catalyst for the acetylene hydration to acetaldehyde

Article abstract of DOI:10.1016/j.cclet.2019.03.049

MCM-41 material was modified by polyethyleneimine (PEI) using ultrasonic assisted impregnation method with different PEI loading (P-MCM-x, x = 0–15 wt%). The synthesised P-MCM-x materials and corresponding Zn/P-MCM-x catalysts were characterised by FTIR, XRD, TEM, BET, XPS, TG and H₂-TPR, as well as their catalytic performance in the hydration of acetylene was investigated. The results showed that the modified materials retained the mesoporous structure with good thermostability, and the corresponding Zn/P-MCM-x displayed the higher catalytic performance than that of Zn/MCM-41 catalyst, especially for the Zn/P-MCM-12 catalyst with about 88% C₂H₂ conversion and 85% selectivity, and the optimal content of PEI is 12 wt%. More importantly, the introduction of PEI enhanced metal-support interaction to make the better metal dispersion and more active sites, and the charge transfer from N atom to Zn species. These all would be responsible for the high activity of the modified Zn catalysts in the acetylene hydration.

Full text of DOI:10.1016/j.cclet.2019.03.049

Accepted Manuscript
Title: A novel and effective Zn/PEI-MCM catalyst for the
acetylene hydration to acetaldehyde
Authors: Qinqin Wang, Mingyuan Zhu, Bin Dai, Jinli Zhang
PII:
DOI:
Reference:
S1001-8417(19)30145-7
https://doi.org/10.1016/j.cclet.2019.03.049
CCLET 4885
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Chinese Chemical Letters
Received date:
Revised date:
Accepted date:
23 January 2019
28 February 2019
27 March 2019
Please cite this article as: Wang Q, Zhu M, Dai B, Zhang J, A novel and effective
Zn/PEI-MCM catalyst for the acetylene hydration to acetaldehyde, Chinese Chemical
Letters (2019), https://doi.org/10.1016/j.cclet.2019.03.049
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Chinese Chemical Letters
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Communication
A novel and effective Zn/PEI-MCM catalyst for the acetylene hydration to
acetaldehyde
Qinqin Wanga, Mingyuan Zhub,c, Bin Daib,c , Jinli Zhanga,*
a school of Chemical Engineering & Technology, Tianjin University, Tianjin 300350, China
b Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, Shihezi 832000, China
c School of Chemistry and Chemical Engineering, Shihezi University, Shihezi 832003, China
Corresponding authors.
E-mail addresses: db_tea@shzu.edu.cn (B. Dai), zhangjinli@tju.edu.cn (J. Zhang)
Graphical Abstract
The introduction of PEI can enhance the metal-support interaction to make the better metal dispersion and more active sites, and
the charge transfer from N atom to Zn species, especially for the Zn/P-MCM-12 catalyst with about 88% C2H2 conversion and
85% selectivity.
ARTICLE INFO
ABSTRACT
Article history:
Received
Received in revised form
Accepted
MCM-41 material was modified by polyethyleneimine (PEI) using ultrasonic assisted
impregnation method with different PEI loading (P-MCM-x, x = 0-15 wt%). The synthesized P-
MCM-x materials and corresponding Zn/P-MCM-x catalysts were characterized by FTIR, XRD,
TEM, BET, XPS, TGandH2-TPR, as well as their catalytic performance in the hydration of
acetylene was investigated. The results showed that the modified materials retained the
mesoporous structure with good thermostability, and the corresponding Zn/P-MCM-x displayed
the higher catalytic performance than that of Zn/MCM catalyst, especially for the Zn/P-MCM-
12 catalyst with about 88% C2H2 conversion and 85% selectivity, and the optimal content of PEI
is 12 wt%. More importantly, the introduction of PEI enhanced metal-support interaction to
make the better metal dispersion and more active sites, and the charge transfer from N atom to
Zn species. These all would be responsible for the high activity of the modified Zn catalysts in
the acetylene hydration.
Available online
Keywords:
Polyethyleneimine
Modified MCM-41
Acetylene hydration
Zinc catalyst
High activity
Acetaldehyde is widely used as a chemical intermediatefor
the production of peracetic acid, acetic anhydride, butylene
glycol, and so on [1, 2]. The hydration of acetylene to give
acetaldehyde has attracted increasing attentionbecause it
provides a more promising route for the industrial production of
acetaldehyde, and it profits from the vast domestic coal reserves
and the increase in oil prices [3]. A stoichiometric amount of
mercuric sulfate hasbeen employedunder strongly acidic
process generates toxic waste containing mercury, which results
in severe environmental problems [4]. Therefore,
environmentally friendly non-mercury-containingcatalysts have
been widely investigated over recent decades.
Numerous transition metal ions, such as Cu2+, Ag+, Cd2+,
and Zn2+, which were either in aqueous solution or in the solid
state in the form of their oxides, phosphates, molybdates,
phosphomolybdates, and tungstates, exhibited initial activityin
the hydration of acetylene [5-13]. Notably, the catalytic activity
conditions for the hydrationof acetylene. However, this catalytic
———

in the hydration of acetylene decreased in the order of Cd > Zn
>Pb [11]. Unfortunately, although the Cd-based catalysts showed
the excellent catalytic performance for the hydration of
acetylene, the toxicity of cadmium limited their application in the
reaction. In addition, the activezeolite catalysts containing
transition metal ions were easily deactivated because the metal
ions were reduced (such as Cu2+, Ag+, Hg2+) or/and carbonaceous
depositswere formed. In view of this, zinc-based catalysts would
be likely to constitute potential replacementsforcadmium-based
catalysts for the hydration of acetylene. In fact, the zinc-based
catalysts preserved the relatively high initial activity in the
hydration of acetylene [11].
thoroughly with deionised water until pH 7 was reached. The
powder wasthen dried at 60 °C and calcined at 500 °C for 6 h
with airflow to obtain the MCM-41 material.
Then, the PEI modified MCM-41 material was prepared by
the ultrasonic assisted impregnation method. A certain amount of
PEI was dissolved in deionised water, and then obtained PEI
solution was added dropwise into the MCM-41 material under
the ultrasonicirradiated for
8 h with argon at ambient
temperature. Finally, the obtained mixture was dried at 100°C
overnight to gain PEI modified MCM-41 material, named P-
MCM. Notably, the synthesizedPEI modified MCM-41 materials
contained different PEI contents: 4 wt%, 6 wt%, 10 wt%, 12
wt%, and 15 wt%, called after P-MCM-4, P-MCM-6, P-MCM-
10, P-MCM-12, and P-MCM-15.
Inprevious studies, the particularly potential support MCM-
41 has been used in the acetylene hydration due to its
exceptionalproperties [14-16], such as the well-organized
mesoporous structure, large surface area, excellent thermal
stabilities and facile surface modification. However, almost no
active sites, almost neutral of surface charge and single Si–OH
groups of the MCM-41 caused to the poor activity and stability
[17-20]. Therefore, it is essential for the surface modification
through introducing the reactive organic functionalgroups to
bond or anchor more metal on the mesoporous MCM-41 surface
to enhance the catalytic performance. It is well known that the
polyethyleneimine(PEI) is a cationic hydrophilic polymerwith a
large amount of charge density, particularly, the high amine
density, good solubility and functionality has been employed in
the preparation andsurface modification for the materials [21-
27]. As a result of these excellent properties, the unique PEI has
always applied invarious systems to play different roles. For
instance, the PEI modified nanocomposites could enhance
adsorption capacity as a functionalized adsorbents and the
modified PEI-MOFs materials could effectively separate CO2
and phosphate sequestration [28-30]. Additionally, PEI also
could be served as a stabilizer to capture nanoparticles [31].
Notably, the adhesion between compounds and carriers surface
can be improved by adding the PEI [32-34].Moreover, PEI also
could be used to prepare multifunctional fluorescent carbon dots
profiting from its picturesque proton sponge mechanism [35].
Hence, inspired by the excellent properties of PEI with ahigh
density ofcharge, a series of PEI modified MCM-41 materials
with different PEI contents were synthesized by using the
ultrasonic assisted impregnation method. And then thePEI
modified MCM-41 materialscapturedzinc active compound as
catalysts for acetylene hydration to acetaldehyde. In this work,
we explored thenature of thestructure and introduction of amine
functional groups for the as-synthesised materials as well as the
influence on the catalytic performance in the acetylene hydration.
Interestingly, the PEI modified Zn catalyst showed the high
catalytic performance in the acetylene hydration. Allofthe
samples were characterised by FTIR, XRD, BET,H2-TPR, TEM,
XPS, and TGA.
The corresponding Zn/P-MCM-x (where x = 4, 6, 10, 12 and
15) catalysts were synthesised using thewet impregnation
technique with deionised water as a solvent. Briefly, a
stoichiometric amount of ZnCl2solutionwas added to the P-
MCM-x powder dropwise under magnetic stirring. The resulting
suspension was stirred for 10 h in the environmental condition
and then evaporated to dryness before the powder was further
dried for 18 h at 100 °C to form the Zn/P-MCM-x catalysts. The
same procedure was followed to prepare the corresponding
Zn/MCM catalyst for comparison. The content of ZnCl2 was 10
wt% in all catalysts.
The synthesised PEI modified MCM-41materials and
corresponding Zn catalysts were carried out by a series of
characterization
techniques.
Fourier-transform
infrared
spectroscopy (FTIR): IS10 FT-IR spectrometer with wavelength
range of 500-4000 cm−1.X-ray diffractometry(XRD): Bruker D8
advanced X-ray diffractometer. Transmission electron
microscopy (TEM): a JEM 2010 electron microscope.X-ray
photoelectron spectroscopy(XPS): an Axis Ultra spectrometer
with a monochromatised Al-Kα X-ray source. Brunauer–
Emmett–Teller (BET):
Temperature-programmed reduction (TPR): anAutoChem 2720
instrument. Thermogravimetric (TG)analysis:over the
a
Micromeritics ASAP 2020.
temperaturerange of 50-1000°C with the heating rateof
20°C/minand a nitrogen flow rate of 10 mL/min.
In brief, the catalytic performance was tested using 2 mL
catalyst in the fixed-bed glass microreactor (i.d. of 10 mm) for
the hydration of acetylene. Firstly, in order to eliminatetheair
atmosphere of the reactor, the nitrogen was continued to purge
for 30 min. Then, when the temperature of reactor reached to 240
°C, the reactant water vapourwas injected the reactor by using a
peristaltic pump. After 0.5 h, the other reactant acetylene was
poured into the system to react with water vapour. Finally, the
reaction products were detected by the gas chromatograph (GC-
2014C). In addition, acetylene conversion(XA) and selectivity to
acetaldehyde(SAA) are the performance indicators for the Zn
catalyst, and the calculation equation is as follows:
In this work, the parent MCM-41 was synthesised by using the
traditional hydrothermal treatment method [36, 37]. Typically,
1.82 g cetyltrimethylammoniumbromide was mixed with a
solution containing 0.2 mol/L of sodium hydroxide at 40°C for 2
h. Then, the tetraethyl orthosilicate was slowly added to the
mixture under vigorous stirring for 2 h. The obtained solution
was transferred to a Teflon autoclave and placed in drying oven
at 110°C for 72 h. The white solid was filtered and washed
−Φ
푋A = Φ
A×100%
A0
Φ
A0
Φ
A
푆AA
=
1−Φ
×100%
A
Where ΦA0 and ΦA are the volume fraction of the initial and
remaining acetylene,respectively.

1635
P-MCM-15
1386
956
1460
800
1238
P-MCM-4
P-MCM-6
P-MCM-12
P-MCM-10
P-MCM-10
P-MCM-12
P-MCM-15
881
P-MCM-6
P-MCM-4
0.0
0.2
0.4
0.6
0.8
1.0
Relative pressure (P/P0)
Fig. 3. N2 adsorption-desorption isotherms of P-MCM-x samples.
800
1000
1200
1400
1600
1800
2000
Wavenumber (cm-1)
In addition, the structure parameters (including surface area,
pore volume and pore diameter) of P-MCM-x samples are listed
in Table S1 in Supporting information. In comparison with the
parent MCM-41, the decrease of surface area and pore volume
would confirm that the PEI has been successfully doped into the
MCM-41 framework. Although the reduction of structure
parameters of PEI modified MCM-41 due to the organic species
plunged into framework and limited the accessible to N2, the P-
MCM-x samples also have high surface area to seize active sites
to catalyze reaction. In addition, the N2 adsorption-desorption
isotherms ofP-MCM-x samples in Fig. 3 could suggest that the
samples retained the mesoporousstructure because of the type IV
isotherm. Furthermore, it is feasible that the further decrease of
structure parameters after the zinc species deposition on the
surface of P-MCM-x samples, and the mesoporous structure was
not destroyed but with the poor ordered pore channels for the
Zn/P-MCM-x samples (shown in Table S1 and Fig. S2 in
Supporting information). Notably, these features also could be
observed from the small-angle XRD patterns in Fig. 4.
Fig. 1. FT-IR spectra of P-MCM-x materials.
Fig. 1 showed the FTIR spectra of P-MCM-x materials. It is
clearly observed that the special groups of MCM-41 framework
were still well retained after the introduction of PEI, which can
be confirmed by the special features at 800, 956, 1238 and 1386
cm-1corresponding to Si–O–Si symmetric stretch, Si–O–H
stretching vibration, Si–O–Si asymmetric stretch and -OH in-
plane bending vibration of MCM-41 [38]. In addition, it is
reported that the features at 1553-1646 cm-1 and 1468 cm-1 could
+
be classified as bending of -NH2 and symmetric bending of NH3
in the silica samples doping by PEI [39, 40]. Thus, at this stage,
it could be considered that the PEI has been successfully doped
into the MCM-41 framework from the FTIR result.
The thermal stabilities of P-MCM-x samples were
performed by the TG experiments, and the results are plotted in
Fig. 2. Firstly, as shown in Fig. 2, the first step of weight loss
below 200 °C could be attributed to the removal of moisture
molecules and/or desorption of organic molecules on the surface
of P-MCM-x samples. Then, the middle of weight loss at the
temperature range of 200-400 °C would be related to the
decomposition of amine groups anchored to the framework.
Moreover, the last step of slight weight loss might be belonged to
the release of surfactant molecules in the samples. Meanwhile,
the corresponding DTG curves were observed two obvious peaks
at 50-150 °C and 300-400 °C in the Fig. S1 in Supporting
information. The first peak could be due to the adsorb water
or/and organic molecules loss; the second peak would be caused
by the decomposition of amine groups.
P-MCM-15
P-MCM-12
P-MCM-10
P-MCM-6
P-MCM-4
2
3
4
5
6
7
8
2 theta (°)
Fig. 4. Small-angle XRD patterns of P-MCM-x samples.
100
95
The diffraction peaks located around 2.4°, 4.1° and 4.8° of
P-MCM-x samples corresponding to the (100), (110) and (200)
planes, respectively, which is the symbol of mesoporous
structure with a hexagonal ordered pores [38]. However, after the
zinc species deposition, the peak intensity reduced and only one
diffraction peak located at 2.4° was found for the Zn/P-MCM-x
samples (shown in Fig. S3 in Supporting information). These
indicated that the addition of PEI and zinc species reduced the
ordered pore channels, which is consist with the BET results.
Interestingly, from the Table S1, the δ (wall thickness) value
increased with the content of PEI for the P-MCM-x samples due
to the decrease of pore diameter after PEI incorporation into
MCM-41. As expected, the δ value of Zn/P-MCM-x samples is
higher than that of P-MCM-x samples, which might suggest that
most of zinc species deposited on the entrance and a portion of
P-MCM-4(a)
90
P-MCM-6
(b)
85
80
75
P-MCM-12(d)
(c)
Ⅰ
Ⅱ
P-MCM-10
Ⅲ
(e)
P-MCM-15
0
100 200 300 400 500 600 700 800 900
Temperature (oC)
Fig. 2. TG curves of P-MCM-x samples.

species entered into the inside pore channels of P-MCM-x
results are shown in Fig. 6. It is clearly found that a reduction
peak at temperature of around 380°C for the Zn/MCM-41
catalyst. For the representativeZn/P-MCM-12 catalyst, there are
two obvious reduction peaks at the temperature of 337°C and
475°C, except for the reduction peak of P-MCM-12 material. It
might be speculated that the low temperature of reduction peak
could be attributed to the reduction of zinc species dispersed on
the support externalsurface, and the other reduction peak might
be belonged to the reduction of the zinc species that entered into
the inside pore channels with strong interaction between the P-
MCM-12 support. These obvious changes could suggest that the
metal-support interaction has been strengthened after the
incorporation of PEI, which may be one of the reasons for the
high activity of Zn/P-MCM-x catalysts in the acetylene hydration
reaction.
samples.
100
80
60
Zn/P-MCM-4
40
Zn/P-MCM-6
Zn/P-MCM-10
Zn/P-MCM-12
20
Zn/P-MCM-15
Zn/MCM-41
0
0
2
4
6
8
10 12 14
Time on stream (h)
Fig. 5. Acetylene conversionduring the hydration of acetylene
catalyzed by Zn/P-MCM-x catalysts.
Moreover, the synthesized Zn/P-MCM-x catalysts were
used to catalyze the hydration of acetylene, and the reaction
conditions were as follow: reaction temperature is 240°C,
reactants ratio is 4 (water vapour is more), and gas hourly space
velocity is 90 h-. From the catalytic activity results in Fig. 5, the
Zn/MCM catalyst displayed a high initial activity, which was
continuously deactivated from 83.5% to 30.0%witha C2H2
conversion loss of about 64.1% after 14 h, indicating the poor
catalytic activity and stability, as well as the selectivity to
acetaldehyde for the Zn/MCM-41 catalyst in the acetylene
hydration reaction. Surprisingly, the Zn/P-MCM-x catalysts
showed the higher catalytic activity and stability than that of the
Zn/MCM-41 catalyst in the same reaction conditions. Specific
contentsare as follows: the C2H2 conversion loss of Zn/P-MCM-
4, Zn/P-MCM-6, Zn/P-MCM-10, Zn/P-MCM-12, and Zn/P-
MCM-15 catalysts was 19.6%, 17.8%, 8.0%, 7.5% and 9.0%,
respectively. In other word, the catalytic activity increased with
the content of PEI, but further increase in PEI amount the C2H2
conversion was not continue to increase but decreased.
Obviously, the Zn/P-MCM-12 displayed the better catalytic
activity with aC2H2 conversion of about88% and selectivity to
acetaldehyde of about85% (shown in Fig. S4 in Supporting
information).Therefore, the catalytic activity results indicated the
addition of PEI could enhance the catalytic activity and stability
of Zn catalyst in the hydration of acetylene, and the optimal
content of PEI is 12 wt%.
Fig. 7. TEM images of fresh Zn/P-MCM-x catalysts.
Fig. 8. TEM images of spent Zn/P-MCM-x catalysts.
Zn/P-MCM-12
Then, the TEM micrographs and particles size distribution
of fresh and spent Zn/P-MCM-x catalysts are shown in Figs. 7
and 8. The apparentblack/darker dots and a broad particles size
distribution could be observed from the fresh Zn/MCM-41
catalyst with an average particle size of 8.1 nm. Else, the average
particle size of spent Zn/MCM-41 catalyst expanded to 13.3 nm
with the conspicuous agglomeration. In other word, the poor
metal dispersion and particles agglomerated may be one of the
reasons of Zn/MCM catalystdeactivation in the acetylene
hydration. However, it turns dust into glory after the PEI
introduced, as shown in Fig. S5(Supporting information), the Zn
species and N species uniformly distributed on the MCM-41
indicated that the PEI was successfully introduced into the
MCM-41framework.On one hand, the metal particles showed a
Zn/MCM-41
P-MCM-12
100
200
300
400
500
600
Temperature (oC)
Fig. 6. H2-TPR profiles of samples.
To explore the influence of PEI modification on the Zn
catalyst, the following experiments were conducted.Firstly, the
H2-TPR was used to reveal the strength of interactionbetween the
metal and support and the reducibility of metal catalysts and the

good dispersion on the outer surface and the average particle size
never exceeded 5 nm with a narrower particles size distribution
of the fresh Zn/P-MCM-x catalysts. On the other hand, the
absence of apparentagglomeration of the spent Zn/P-MCM-x
catalysts suggested that the addition of PEI could prevent the
particles agglomerated during the reaction. These would be
responsible for the high catalytic performance of the Zn/P-
MCM-x catalysts in the acetylene hydration.
eV and 402.2 eV (listed in Table 1) for the fresh Zn/P-MCM-12
catalyst. Some studies have been pointed out that the N 1s peak
at higher binding energy (400-402 eV) could be related to the
adsorption of metal ions (Mn+) [42-44], which would cause to the
positive polarization. Therefore, in this study, the N 1s peak at
low binding energy could be attributed to the N of the amino
group, the other N 1s peak would originate from the charged
+
ammonium, such as –NH3 or –NH2…M2+ [45, 46]. However,
after the reaction, the N 1s consisted of three peaks and the
binding energies slight reduced indicated that the metal-support
interaction appeared during the reaction. It is well known that the
N atom derived from the amino group has a free electric pair,
which could be formed the coordination bonds with the metal
ions and resulted to the increase of metal electron density to
obtain more active sites. This can be further confirmed by the Zn
2p3/2 XPS spectra for the Zn/P-MCM-12 catalyst (Fig. 9B). As
shown in Table 1, the binding energies of Zn 2p3/2 peaks in Zn/P-
MCM-12 catalyst is lower than that of Zn/MCM-41 catalyst,
indicating that the Zn species obtained the electrons from the PEI
modified support caused to the lower Zn 2p3/2binding energies.
These could imply that the stronger interaction between Zn2+ and
amino group from the PEI modified support, as well as for the
spent Zn/P-MCM-12 catalyst. In addition, the elemental
compositions in Table 1indicated the addition of PEI could
enrich more Zn species and present the Zn species loss (Zn loss
of 13.8% is obvious lower than that of Zn/MCM-41 catalyst).
Therefore, the stronger metal-support interaction, more active
sites and lower Zn loss would be also responsible for the high
catalytic performance in the hydration of acetylene.
(B)
spent Zn/P-MCM-12
(A)
spent Zn/P-MCM-12
spent Zn/MCM-41
fresh Zn/P-MCM-12
fresh Zn/P-MCM-12
fresh Zn/MCM-41
396
398
400
402
404
1018
1020
1022
1024
1026
1028
Binding energy (eV)
Binding energy (eV)
Fig. 9. The high-resolution XPS spectra for the N 1s (A) and the Zn
2p (B) of the catalysts.
Lastly, in order to measure the chemical state and surface
composition of the representative Zn/P-MCM-12 catalyst, the
XPS experiment was performed. From the Fig. S6 (Supporting
information), the obvious peak at the binding energy of 400.0 eV
indicated that the presence of the nitrogen (N 1s) of the Zn/P-
MCM-12 catalyst [41], which confirmed that the PEI has been
doped into the MCM-41 framework due to the N atoms derived
from the PEI. More importantly, the N 1s peak (Fig. 9A) has
been fitted well by two peaks with the binding energies of 400.0
Table1
Surface atomic composition (%) and binding energies ofcatalysts.
Composition (At %)
Binding energy (eV)
Samples
N
Zn
C
Zn 2p3/2
1023.2
1023.1
1022.6
1022.0
Zn 2p3/2
N 1s
Fresh Zn/MCM-41
Spent Zn/MCM-41
Fresh Zn/P-MCM-12
Spent Zn/P-MCM-12
/
/
3.13
2.27
3.78
2.96
10.56
11.69
10.98
25.72
1024.0
1023.6
1023.2
1022.5
/
/
/
/
3.73
2.46
400.0
399.8
402.2
400.9
401.9
In this work, a simple ultrasonic assisted impregnation
method was used to synthesize PEI modified MCM-41material
with different PEI amount. FTIR results suggested that the PEI
has been successfully doped into the MCM-41 framework. The
TD-DSC results confirmed the good thermostability of P-MCM-
x materials. BET and XRD indicated that the P-MCM-x materials
retained the mesoporous structure with hexagonal pores. In the
activity tests, the corresponding Zn/P-MCM-x displayed the
higher catalytic performance than that of Zn/MCM-41 catalyst in
the hydration of acetylene. Notably, the Zn/P-MCM-12 catalyst
showed the better activity with aC2H2 conversion of about88%
and selectivity to acetaldehyde of about85%, suggested the
optimal content of PEI is 12 wt%. Furthermore, the H2-TPR
results implied that the addition of PEI could enhance the
interaction between metal and support that related to the high
activity of Zn/P-MCM-12 catalyst. The better metal dispersion
and narrower particles size of Zn/P-MCM-x catalysts can be
verified by the TEM, as well as the fact that the introduction of
PEI prevented the particles agglomerated. More importantly, the
XPS results confirmed the strong metal-support interaction and
the charge transfer from N atom to Zn species. Else, the
incorporation of PEI not only enriched more active sites but also
restrained the Zn species loss during the reaction. These all
would be responsible for the high activity of the modified Zn
catalysts in the acetylene hydration. We believe that this work
would be as a basic research to develop and design the powerful
metal catalysts in the hydration of acetylene to acetaldehyde for
industrial applications.
Acknowledgments
We gratefully acknowledge the financial support from the
Program for Changjiang Scholars and Innovative Research Team
in University (No. IRT_15R46), Yangtze River Scholar Research
Project of Shihezi University (No.CJXZ201601),the High-level
Talent Scientific Research Project of Shihezi University (No.
RCZX201405), and the National Natural Science Fundation of
China (Nos.U1403294, 21666033).

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