Full Papers
doi.org/10.1002/ejic.202001073
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High-Performance Catalysts Derived from Cupric
Subcarbonate for Selective Hydrogenation of Acetylene in
an Ethylene Stream
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A high-performance base metal catalyst for acetylene selective
hydrogenation was prepared from cupric subcarbonate
(Cu2(OH)2CO3) by thermal treatment with an acetylene-contain-
ing gas followed by hydrogen reduction. The characterization
results revealed that the copper catalyst was composed of
interstitial copper carbide (CuxC) and metal Cu, which were
embedded in porous carbon matrix. The CuxC crystallites, which
showed outstanding hydrogenation activity, were derived from
the hydrogen reduction of copper (II) acetylide (CuC2) which
was generated from the reaction between acetylene and
Cu2(OH)2CO3. The Cu particles and porous carbon were
generated from the unavoidable thermal decomposition of
CuC2. The prepared Cu-derived catalyst completely removed
the acetylene impurity in an ethylene stream with a very low
°
over-hydrogenation selectivity at 110 C and atmospheric
pressure. No obvious deactivation was observed in a 180-h test
run. In the Cu-derived catalyst, CuxC served as the catalytic site
for H2 dissociation, Cu mainly functioned as the site for selective
hydrogenation of acetylene, whereas the porous carbon matrix
posed a steric hindrance effect on the chain growth of linear
hydrocarbons so as to suppress the undesired oligomerization.
Introduction
lysts deactivate quickly during the acetylene hydrogenation
due to the vigorous formation of oligomers.[32,33] In addition, Fe-
based,[34,35] Cu-based[36–38] and CeO2-based[39–41] catalysts were
also reported to perform well in selective hydrogenation of
acetylene. For example, Cu catalysts were intrinsically selective
to alkene in alkyne hydrogenation due to the marked difference
of adsorption energy between alkyne and the corresponding
alkene.[7,42,43] However, Cu catalysts are much less active than Pd
catalysts in hydrogenation, and, as a result, the selective
hydrogenation of acetylene over Cu catalysts often takes place
at higher temperatures. Acetylene is prone to oligomerize to
produce green oil at high temperatures, and the oligomers will
foul the catalyst surface, thus leading to rapid catalyst
deactivation.[7,44] Bridier et al[45] reported that CO-modified Cu-
based catalyst displayed an enhanced propene selectivity and
suppressed the formation of oligomers. They proposed that the
addition of CO altered the surface structure of Cu irreversibly,
resulting in smaller Cu ensembles and minimizing the CÀ C
coupling reaction. Another effective approach to suppressing
the formation of oligomers is to lower the reaction temperature.
McCue et al.[46] and Kyriakou[47] reported that the Pd-promoted
Cu catalysts exhibited outstanding performance in selective
hydrogenation of acetylene at low temperatures, by taking
advantage of the high ethylene selectivity of Cu and the high
activity of Pd.
Ethylene is mainly produced by naphtha cracking and is used as
a basic petrochemical raw material for synthetic resins, such as
polyethylene. For polymer-grade ethylene, acetylene impurity
must be reduced below an acceptable level (5 ppm) to protect
the downstream polymerization catalyst and to avoid ungraded
polymer products.[1–4] In industry, the preferred method of
removing the acetylene impurity in ethylene stream is by
selective hydrogenation of acetylene to ethylene product.[5,6]
The most commonly used catalyst is the low-surface-area
alumina-supported Pd catalyst modified by Ag.[7,8] In addition,
Ga,[9–11] Zn,[12–14] Au,[15–17] Cu,[18–21] and In[22,23] are also used as the
promoters. Recently, Liu et al.[24,25] and McCue et al.[26] reported
that palladium sulfide and palladium phosphides exhibited
excellent ethylene selectivity at complete acetylene conversion
°
above 125 C. In general, one major disadvantage associated
with precious metal catalysts is the high cost.
Ni-based catalysts have been extensively explored for
replacing supported Pd catalysts.[27–31] However, Ni-based cata-
[a] C. Lu, A. Zeng, Prof. Y. Wang, Prof. A. Wang
State Key Laboratory of Fine Chemicals
School of Chemical Engineering
Dalian University of Technology
Dalian 116024, P. R. China
E-mail: wangyao@dlut.edu.cn
In our previous investigation, a new interstitial copper
carbide (CuxC) was synthesized by reducing copper (I) acetylide
[b] Prof. Y. Wang, Prof. A. Wang
[48]
°
(Cu2C2) in H2 at 180 C. The DFT calculation results indicated
that the CuxC was more active than the Cu catalyst in H2
dissociation. The Cu2O-derived catalyst, consisting of CuxC and
Cu, was remarkably active, selective, and stable in acetylene
selective hydrogenation in an ethylene stream. In the present
work, Cu2(OH)2CO3 was used to prepare the catalysts for
Liaoning Key Laboratory of Petrochemical Technology and Equipment
Dalian University of Technology
Dalian 116024, P. R. China
Supporting information for this article is available on the WWW under
Eur. J. Inorg. Chem. 2021, 997–1004
997
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