A novel risedronic acid-modified Nieuwland catalyst for acetylene dimerization

Article abstract of DOI:10.1016/j.catcom.2019.105922

Nieuwland catalyst (NC) was modified with different phosphonic acids (P_x) and evaluated for their acetylene dimerization activity in monovinyl acetylene (MVA) production. Nearly 49.2% of acetylene conversion and 80.3% of MVA selectivity were obtained in 5 mol% risedronic acid (P₂)-modified NC under an acetylene-gas space velocity of 105 h^?1 at 80 °C, which was 17.8% higher than the yield of the control NC. The characterization results of NC and P₂–NC indicated that the addition of P₂ effectively enhanced the stability of the Cu ions and inhibited oxidation of the active component Cu⁺, improving their catalytic activity and long-term stability.

Full text of DOI:10.1016/j.catcom.2019.105922

CatalysisCommunications136(2020)105922
Contents lists available at ScienceDirect
Catalysis Communications
journal homepage: www.elsevier.com/locate/catcom
Short communication
A novel risedronic acid-modified Nieuwland catalyst for acetylene
dimerization
⁎
Qixia Zhanga,1, Congcong Lia,1, Juan Luoa, Jianwei Xiea,b, , Jinli Zhangc, Bin Daia
a School of Chemistry and Chemical Engineering, Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, Shihezi University, North 4th road,
Shihezi 832003, China
b College of Chemistry and Bioengineering, Hunan University of Science and Engineering, Yangzitang Road, Yongzhou 425100, China
c School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
A R T I C L E I N F O
A B S T R A C T
Keywords:
Nieuwland catalyst (NC) was modified with different phosphonic acids (Px) and evaluated for their acetylene
dimerization activity in monovinyl acetylene (MVA) production. Nearly 49.2% of acetylene conversion and
80.3% of MVA selectivity were obtained in 5 mol% risedronic acid (P2)-modified NC under an acetylene-gas
space velocity of 105 h−1 at 80 °C, which was 17.8% higher than the yield of the control NC. The character-
ization results of NC and P2–NC indicated that the addition of P2 effectively enhanced the stability of the Cu ions
and inhibited oxidation of the active component Cu+, improving their catalytic activity and long-term stability.
Acetylene dimerization
Monovinylacetylene
Cu-based catalyst
Modified Nieuwland catalyst
1. Introduction
creation of metal/acid bifunctional sites [12]. Recently, Wang et al.
reported that 1-hydroxyethylidene-1,1-diphosphonic acid-modified Cu/
Chloroprene rubber is a general-purpose polymer material produced
by the polymerization of chloroprene (CP). It is an important type of
synthetic rubber with broad application prospects [1]. In China, where
coal is abundant, CP is mainly produced through C2H2-based processes.
However, the production efficiency of CP is limited by the dimerization
of acetylene to monovinyl acetylene (MVA). The traditional catalyst for
acetylene dimerization is the Nieuwland catalyst (NC), invented by
Nieuwland in the 1930s, which consists of CuCl–NH4Cl–HCl–H2O [2].
This catalyst has always been disadvantaged by low conversion, low
selectivity, and high polymer. Therefore, more effective catalysts for
acetylene dimerization are urgently required. In recent years, NC have
been modified by second metal addition [3–5], ligand modification
[6–9], and optimization and intension [10,11]. These modifications
have significantly advanced the acetylene dimerization process. How-
ever, they also incur drawbacks such as low acetylene conversion and
low MVA selectivity.
activated carbon (AC) catalyst is highly active in acetylene hydro-
chlorination. This modification boosted the coordination ability of PA
and improved the dispersion of active components on the AC support
[13]. Kou et al. modified Cu-Zn-Al hydrotalcite-derived oxides with
amino trimethylene phosphonic acid (ATMP), and catalytically syn-
thesized isobutanol and ethanol from syngas. The lattice of the CuZnAl-
HTDO catalyst is partially destroyed due to the complexation of Cu2+
ions with ATMP. It leads to lattice strain and defects, and improves the
adsorption and dissociation of CO at the active site of Cu, which ac-
celerates the reaction rate of CO insertion [14]. Zhang et al. modified
Au catalysts with etidronic acid and nitrilotri(methylphosphonic acid)
for acetylene hydrochlorination. The transfer of electrons from het-
eroatoms to Aun+ due to the coordination of N, P and O, which in-
creases the density of electron clouds around the active center [15].
Although PAs are excellent modifiers or complexing agents in several
catalytic reactions, they have rarely been considered in acetylene di-
merization.
Phosphonic acids (PAs), a class of organic compounds containing
the -PO(OH)2 group, are often used as phosphorus precursors, com-
plexing agents, or catalyst-modifying ligands in the catalysis fields
[12–17]. Hao et al. reported an efficient and convenient method for
vanillin hydrodeoxygenation using PAs-modified Pd/Al2O3 as the cat-
alyst at low temperature. They attributed the improvement to the
We have been endeavoring to develop efficient modified NCs for the
acetylene dimerization reaction [4,5,7–9]. As part of these efforts, we
propose a P2-modified NC catalyst that converts 49.2% of the C2H2 with
an MVA selectivity of 80.3%. The effect of P2 on the microstructure and
active components of the catalyst is examined by various techniques:
⁎ Corresponding author at: School of Chemistry and Chemical Engineering, Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan,
Shihezi University, North 4th road, Shihezi 832003, China.
E-mail address: cesxjw@foxmail.com (J. Xie).
1 Equal contribution to this work.
https://doi.org/10.1016/j.catcom.2019.105922
Received 21 October 2019; Received in revised form 13 December 2019; Accepted 24 December 2019
Availableonline24December2019
1566-7367/©2019ElsevierB.V.Allrightsreserved.

Q. Zhang, et al.
CatalysisCommunications136(2020)105922
Fig. 1. Structures of the six ligands (P1-P6).
Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction
(XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetry/
derivative thermogravimetry (TG/DTG), transmission electron micro-
scopy (TEM), temperature programmed desorption-mass spectrometry
(TPD–MS), and inductively coupled plasma (ICP) spectroscopy.
2.4. Catalyst characterization
The NC and P2–NC reacted for seven hours were denoted as the used
NC and P2–NC, respectively. The fresh and used NC and P2–NC were
maintained at 3 °C for 6 h in a refrigerator. After cooling, the catalysts
were filtered from the catalytic solution, washed with water, and dried
in a vacuum oven at 55 °C to obtain a solid catalyst for characterization.
The TG/DTG was performed in a NETZSCH STA 449 F3 Jupiter
system (nitrogen atmosphere, temperature range 50–900 °C, ramp rate
10 °C/min). The crystal structures of the samples were determined by
XRD (2θ = 10–90°). The FT-IR spectra of the catalysts were determined
2. Experimental section
2.1. Materials
Glyphosine (P1), risedronic acid (P2), cytidine 5′-monophosphate
(P3), hydroxyphosphono-acetic acid (P4), 2-phosphonobutane-1,2,4-
tricarboxylic acid (P5), phenylphosphonic acid (P6), CuCl (99%), and
NH4Cl (purity ≥99.5%), were purchased from Adamas and directly
used without purification. The molecular structure of the six ligands are
shown in Fig. 1. The NCs containing Px are denoted as Px-NC. The
amount of Px (in moles) was based on the CuCl quantity.
by
a Bruker Vertex70 FTIR spectrometer (wavenumber range
500–4000 cm−1). The XPS data was performed in a Kratos AXIS Ultra
DLD spectrometer with a monochromatized Al-Kα x-ray source, the
deconvolution of the XPS peaks are obtained by the XPSPEAK41 soft-
ware to process XPS data. The morphologies and microstructures of the
samples were recorded by a JEM2100F TEM instrument. The TPD-MS
experiments were performed with a Micromeritic ASAP 2720. The ab-
solute Cu contents in the samples were tested by ICP atomic emission
spectroscopy (710ES, Varian, USA).
2.2. Catalyst preparation
The catalyst performances were evaluated in a bubble column re-
actor (length = 400 mm, outer diameter = 40 mm, inner dia-
meter = 10 mm). As a control, an unmodified NC was prepared by
dissolving 5.35 g (0.1 mol) of NH4Cl and 9.9 g (0.1 mol) of CuCl in
10 ml of deionized water at 80 °C. For the experimental specimens, an
appropriate molar amount of Px (based on the CuCl quantity as men-
tioned above) was added to the NC. Scheme S1 shows the formation of
the gas-phase products in the dimerization process and the catalyst
performance evaluation is performed in the C2H2 dimerization device
(Fig. S1).
3. Results and discussion
3.1. Catalytic activities of NC and Px-NC
The performances of the NC and Px-NCs were initially tested under
the same fixed conditions (T = 80 °C, C2H2 gas hourly space velocity
GHSV(C2H2) = 105 h−1). The results are shown in Fig. 2. All Px-NCs
exhibited a higher catalytic activity than NC; specifically, the catalytic
activity decreased in the order P2-NC > P1-NC > P6-NC > P4-
NC > P3-NC > P5-NC > NC. The best performer (P2-NC) converted
49.2% of the C2H2 with an MVA selectivity of 80.3%. The conversion
improvement of P2-NC over NC was 39.5%. Next, we screened the P2
content (Fig. S2) and the GHSV(C2H2) (Fig. S3). The performance was
maximized at a P2 content of 5% (P2/Cu = 0.05/1). Under a GHSV
(C2H2) of 80 h−1, the conversion performance improved to 51.1%. In a
long-term test, the 5% P2-NC delivered both excellent activity (51.1%
C2H2 conversion and 78.8% MVA selectivity) and satisfactory stability
(Fig. S4). Therefore, P2 can significantly enhance the catalytic perfor-
mance and extend the lifetime of NC for acetylene dimerization.
Contrasting the ligand structure, ligands P1 and P2 contain two
phosphonic acid groups in six ligands, which may play an important
role in high catalytic activity. Phosphonic acid groups are activated by
π-electron cloud of benzene, so P6 has a remarkable effect in the re-
action among the P3-P6 modified catalysts. By the same way, the
2.3. Analytical methods
The criteria of the catalytic performance, namely, the acetylene
conversion (X) and MVA selectivity (S), were respectively computed as
follows:
λ2 + 2λ3 + 2λ4 + 3λ5
X =
S =
× 100%
λ1 + λ2 + 2λ3 + 2λ4 + 3λ5
2λ3
× 100%
λ2 + 2λ3 + 2λ4 + 3λ5
where λ1, λ2, λ3, λ4, and λ5 are the volume fractions of the gas products
C2H2, CH3CHO, MVA, 2-chloroprene (CP), and divinylacetylene (DVA),
respectively.
2

Q. Zhang, et al.
CatalysisCommunications136(2020)105922
Fig. 2. Catalytic performances of the Px–NCs (P1–P6) on acetylene dimerization: (a) conversion of C2H2 and (b) selectivity of MVA. Reaction conditions: T = 80 °C,
GHSV (C2H2) = 105 h−1, Px /Cu(I) = 0.05/1.00.
pyridine of ligands P2 may also be an important influencing factor for
enhancing catalytic activity. Therefore, it can be concluded that the
pyridine and two phosphonic acid groups play an important role in
higher catalytic activity of P2-NC among the modified catalysts.
3.2. Catalyst characterization
3.2.1. Effect of P2 additive on catalyst appearance
During the reaction, black solids appeared in the reacting NC and
P2-NC catalysts (Fig. S5), part of the acetylene was polymerized into a
high-molecular-weight polymer that adsorbed and encapsulated the
active component Cu. Such Cu sequestering is an important cause of
catalyst deactivation [3]. Moreover, consistent with the long-term test
results, the polymer content was significantly lower in P2-NC than in
NC. The loss of active component was further confirmed by ICP
(Table 1).
Fig. 3. XRD spectra of the fresh and used NCs and P2–NCs after calcination.
3.2.2. Effect of P2 additive on the catalyst microstructure
From the HR-TEM analysis, we can see that the major differences
and used NC and P2-NC after calcination. The diffraction peaks at 28.5°,
33.0°, 47.4°, 56.3°, 69.3°, 76.5°, and 88.3° correspond to the (111),
(200), (220), (311), (400), (331) and (422) crystal faces of CuCl, re-
spectively [18]. The spectrum of the fresh P2-NC reveals additional
peaks at 43.3°, 50.4°, and 74.1°, which are contributed by the (111),
(200) and (220) crystal faces of Cu, respectively. These peaks are not
obvious in the spectrum of the used P2-NC, implying that Cu+ was
reduced to Cu0 when the ligand P2 interacted with Cu+ during the
catalyst preparation, and that Cu0 was oxidized to Cu+ after seven
hours of the reaction.
between NC and P2-NC are microstructure of Cu crystal (Fig. S6 a-d)
and the irregular conglomerates are Cu crystals. Meanwhile, the mi-
crostructure of the fresh P2–NC revealed many intertwined lamellar
crystals. Interestingly, this layer of staggered structures might comprise
the active component Cu. Next, it can be found that the high crystal-
linity and the CuCl single-crystal (Fig. S6 e-h). Typical d-spacing of
0.31 nm and 0.27 nm corresponded to the (111) and (200) planes of the
CuCl crystal, respectively. Many CuCl (200) crystal faces (d = 0.26 nm)
appear in fresh and used P2-NC.
The HRTEM images confirm that the P2 modification changed the
crystal morphology. To explore the crystal structure of Cu in the cata-
lyst, the sample was calcined in a tube furnace under a nitrogen at-
mosphere at 450 °C for 0.5 h. Fig. 3 shows the XRD patterns of the fresh
3.2.3. Coordination between the active components and functional groups
of P2
Fig. 4 shows the FT-IR spectra of the fresh NCs and P2–NCs. The
absorption peak at 3164.52 cm−1 in the fresh NC is the OH stretching
vibration induced by chemisorbed water, adsorbed copper hydroxyl
groups, and aqua complexes [19]. In the fresh P2-NC spectrum, the
peak attributable to OeH telescopic vibrations is blue shifted by
3.57 cm−1 relative to the NC peak, and the absorption peak at
1300–900 cm−1 may be contributed by phosphorus-containing groups
(P]O and P–OH) [20]. The latter peak would form if the phosphorus-
containing group in the ligand were coordinated with Cu in the fresh
P2-NC.
Table 1
+
Relative contents and binding energies of Cu and Cu2 + in the four samples,
determined by XPS and ICP.
Sample
Composition (%)a
Cu% (Metal ion content)b
Cu loss (%)
Cu+
Cu2+
Fresh NC
Used NC
Fresh P2-NC
Used P2-NC
72.48
62.76
80.97
72.96
27.52
37.24
19.03
27.04
42.08
34.97
42.9
16.90
5.48
40.53
Fig. S7 shows the FT-IR spectra of all catalysts, which can be further
explored the effect of functional groups on the catalyst. Obviously, the
peaks of phosphorus-containing groups (1300–900 cm−1) appears in
a
Determined by XPS.
Determined by ICP.
b
3

Q. Zhang, et al.
CatalysisCommunications136(2020)105922
Fig. 4. FTIR spectra of the fresh NCs and P2–NCs.
the FT-IR spectra of the fresh P1-NC, P2-NC and P6-NC. In the fresh P2-
NC, the larger peaks at 1300–900 cm−1 is higher than other catalysts,
which proves that the coordination ability between Cu and P2 is
stronger than other catalysts. Combined with the results of the catalytic
activity, it can be further confirmed that the pyridine and two phos-
phonic acid groups play a vital role in higher catalytic activity of the P2-
NC among the modified catalysts.
Fig. 5. XPS spectra of Cu 2p3/2 in the fresh and used catalysts.
(5%), the P2-NC was stable and achieved an acetylene conversion of
49.2% with an MVA selectivity of 80.3% under an acetylene GHSV of
105 h−1 at 80 °C. The NC and P2–NC were characterized by FT-IR, HR-
TEM, TG/DTG, XPS and ICP. The results indicate that coordination
between Cu and P2 enhances the thermal stability of the Cu ions.
During the reaction, the oxidation of the active component Cu+ is ef-
fectively inhibited by P2. Furthermore, the P2 additive also inhibits the
loss of Cu ions from the catalyst, vitally enhancing the long-term sta-
bility of the catalyst. Therefore, P2 is an excellent phosphorus-con-
taining modifier for NC with high catalytic activity and long-term sta-
bility.
3.2.4. Role of coordination between the catalyst and P2 (determined by TG/
DTG analysis)
From the TG/DTG analysis, we see that the major differences be-
tween NC and P2–NC are temperature range of the third mass loss (Fig.
S8 and Table S1). The temperature of the first mass loss, attributable to
the quality loss of crystal water [8,9], was approximately the same in
both NC. This result was confirmed by FT-IR analysis of the catalysts
containing crystal water. In the case of fresh NC and P2-NC, the second
stage included the loss of NH3 [21]. In contrast, the temperature of the
final mass loss, which mainly reflected the loss of CuCl, greatly different
between the fresh NC and fresh P2-NC (463–700 °C vs 543–818 °C). This
difference probably caused by the coordination effect between copper
and P2. In addition, all modified catalysts were characterized by TG/
DTG (Fig. S9), which shown the temperature of the final mass loss in
fresh P2–NC was higher than other modified catalysts. It is inferred that
the coordination between Cu and P2 enhances the thermal stability of
the Cu ions.
Declaration of competing interest
There are no conflicts of interest to declare.
Acknowledgments
We acknowledge the National Natural Science Foundation of China
(No. 21776179 and 21463021) for their financial support.
3.2.5. Valence changes in the active species
Author Contributions Section
The XPS analysis provides the chemical state and distribution of the
active component Cu in the catalyst before and after the reaction. The
XPS peaks at 932.13 and 933.66 eV in Fig. 5 are derived from Cu+ and
Cu2+, respectively [8,9,13]. Table 1 lists the relative Cu2+ and Cu+
contents in the NC catalysts, derived from the relative areas of their XPS
peaks. The relative Cu+ contents were 72.48% and 80.97% respectively
in the fresh NC and P2–NC, and 62.76% and 72.96% respectively in the
used NC and P2–NC. In the P2–NC, the P2 reduction induced the partial
reduction of Cu2+ to Cu+, confirming that the Cu0 in the XRD analysis
(Fig. 3) was contributed by the reduction of P2. Meanwhile, the Cu
contents were 42.08% and 42.9% respectively in the fresh NC and
P2–NC, and 34.97% and 40.53% respectively in the used NC and
P2–NC. This implies that the Cu-ion loss was much lower in P2–NC than
in NC; that is, the P2 additive effectively inhibited the loss of Cu ions
from the catalyst.
Qixia Zhang: performed the experiments and analyzed the data,
wrote the manuscript and supporting information.
Congcong Li: analyzed the data.
Juan Luo: performed the experiments.
Jianwei Xie: designed the project, wrote the manuscript, super-
vision.
Jinli Zhang: reviewed and edited the manuscript.
Bin Dai: designed the project, reviewed and edited the manuscript.
Declaration of Competing Interests
The authors declare that they have no known competing financial
interests or personal relationships that could have appeared to influ-
ence the work reported in this paper.
4. Conclusions
Appendix A. Supplementary data
An NC system was modified with risedronic acid (P2) to accelerate
the acetylene dimerization reaction. At the optimized P2 concentration
Supplementary data to this article can be found online at https://
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