Linear-regioselective hydromethoxycarbonylation of styrene using Ru-clusters/CeO2 catalyst

Article abstract of DOI:10.1016/S1872-2067(19)63527-8

Hydroalkoxycarbonylation of olefins has been considered to be one of the most attractive methods to synthesize esters. Controlling the regioselectivities of linear esters (L) and branched esters (B) is a challenging project for researchers working in this reaction. Although most of the attention has been paid to control the regioselectivity through ligand design in homogeneous catalytic systems, study in the area is still limited. Herein, Ru-clusters/CeO₂ is employed as a heterogeneous catalyst for the hydromethoxycarbonylation of styrene without any additives. After optimization of the reaction conditions, the conversion of styrene is > 99% with 83% and 12% regioselectivity of linear and branched ester, respectively. By using different supports (CeO₂ (nanoparticle), CeO₂-rod, and CeO₂-cube), three catalysts including Ru-clusters/CeO₂, Ru/CeO₂-rod, and Ru/CeO₂-cube are prepared and applied in the reaction. Structural characterizations demonstrate that the L/B ratio is related to the Ru size of supported Ru catalysts. Further Raman characterization and NH₃-TPD demonstrate that the metal-support interaction and the concentration of oxygen vacancy of the catalyst have a great influence on the Ru size. The mechanism and kinetic analysis for this reaction are also investigated in this work.

Full text of DOI:10.1016/S1872-2067(19)63527-8

Chinese Journal of Catalysis 41 (2020) 963–969
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
Linear-regioselective hydromethoxycarbonylation of styrene using
Ru-clusters/CeO2 catalyst
Jinghua An a,b, Yehong Wang a, Zhixin Zhang a, Jian Zhang a, Martin Gocyla c,
Rafal E. Dunin-Borkowski c, Feng Wang a,*
a State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences,
Dalian 116023, Liaoning, China
b University of Chinese Academy of Sciences, Beijing 100049, China
c Ernst Ruska Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Juelich GmbH, Juelich 52425,
Germany
A R T I C L E I N F O
A B S T R A C T
Article history:
Hydroalkoxycarbonylation of olefins has been considered to be one of the most attractive methods
to synthesize esters. Controlling the regioselectivities of linear esters (L) and branched esters (B) is
a challenging project for researchers working in this reaction. Although most of the attention has
been paid to control the regioselectivity through ligand design in homogeneous catalytic systems,
study in the area is still limited. Herein, Ru-clusters/CeO2 is employed as a heterogeneous catalyst
for the hydromethoxycarbonylation of styrene without any additives. After optimization of the
reaction conditions, the conversion of styrene is > 99% with 83% and 12% regioselectivity of linear
and branched ester, respectively. By using different supports (CeO2 (nanoparticle), CeO2-rod, and
CeO2-cube), three catalysts including Ru-clusters/CeO2, Ru/CeO2-rod, and Ru/CeO2-cube are pre-
pared and applied in the reaction. Structural characterizations demonstrate that the L/B ratio is
related to the Ru size of supported Ru catalysts. Further Raman characterization and NH3-TPD
demonstrate that the metal-support interaction and the concentration of oxygen vacancy of the
catalyst have a great influence on the Ru size. The mechanism and kinetic analysis for this reaction
are also investigated in this work.
Received 31 October 2019
Accepted 18 December 2019
Published 5 June 2020
Keywords:
Regioselectivity
Ru-clusters/CeO2
Ester
Hydromethoxycarbonylation
Olefins
Heterogeneous catalysis
© 2020, Dalian Institute of Chemical Physics, Chinese Academy of Sciences.
Published by Elsevier B.V. All rights reserved.
Esters exist in various natural products such as green olives
and pears and have numbers of applications on the production
of perfumes, flavorings, etc. [1]. Consequently, various methods
have been reported to synthesize esters such as the esterifica-
tion of carboxylic acids with alcohols [2], the condensation of
acid chlorides and alcohols [3] as well as the alcoholysis of ni-
triles [4]. Compared with those methods, the functionalization
of olefins in the presence of carbon monoxide (CO) and alco-
hols, which is named as hydroalkoxycarbonylation of olefins,
has been considered to be one of the most attractive methods
for synthesizing esters owing to the 100% of the atom economy
and the using of readily available starting materials [5–15].
Controlling regioselectivity is a challenging task for chemists
working in hydroalkoxycarbonylation of olefins [9,15,16]. Nu-
merous researchers have attempted to control the regioselec-
tivity through ligand design or modification in homogeneous
* Corresponding author. Tel/Fax: +86-411-84379798; E-mail: wangfeng@dicp.ac.cn
This work was supported by the Strategic Priority Research Program of Chinese Academy of Sciences (XDB17020300), and the National Natural Sci-
ence Foundation of China (21721004, 21690084, and 21690080).
DOI: S1872-2067(19)63527-8 | http://www.sciencedirect.com/science/journal/18722067 | Chin. J. Catal., Vol. 41, No. 6, June 2020

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Jinghua An et al. / Chinese Journal of Catalysis 41 (2020) 963–969
catalytic systems. For example, monodentate N-phenylpyrrole
phosphine ligand was designed by Beller’s group [1] and ap-
plied in hydroalkoxycarbonylation of olefins with high regiose-
lectivities of branched esters owing to the steric hindrance of
the ligand (up to 91%), which had been verified through the
density functional theory (DFT) calculation (Scheme 1a). Alt-
hough it is well known that monodentate phosphine ligands are
favorable for the production of branched esters, there are still
some exceptions. Recently, a monodentate cage phosphaada-
mantane ligand in combination with Lewis acid such as SnCl2
was reported to enhance the regioselectivities of the linear
esters in the range of 70%–96% when PdCl2 was used as the
catalyst (Scheme 1b) [17]. Additionally, considering the fact
that more attention has been turned to heterogeneous catalytic
system owing to the difficulties in the separation as well as
reusability of homogeneous catalysts [18], the investigation of
factors affecting the regioselectivity attracts more and more
attention in heterogeneous catalytic system. Recently, a heter-
ogeneous catalytic system was reported and high regioselectiv-
ities of branched esters (up to 91%) were obtained with
Pd-TPPTS-OTPPTS complex supported on acidic resin as the
heterogeneous catalyst (Scheme 1c) [19,20]. They found that
the reaction regioselectivity was remarkably impacted by the
pore size of the support owing to the steric confinement effect
[20]. Therefore, the development of a greener heterogeneous
catalytic system with high activity and excellent regioselectivi-
ty, especially of linear esters, as well as the in-depth investigat-
ing of the factors affecting regioselectivity is urgent for the re-
action.
In our previous works, Ru-clusters/CeO2 has been used in
various carbonylation reactions [21–23]. For example, we re-
ported the synthesis of methyl propionate from hydromethox-
ycarbonylation of ethylene over Ru-clusters/CeO2 catalyst [21].
Although excellent catalytic performance was obtained, there is
no regioselectivity for methyl propionate. Herein,
Ru-clusters/CeO2 was used as the catalyst for hydromethox-
ycarbonylation of a terminal olefin, that is, styrene, to investi-
gate the factors influencing the regioselectivity. The conversion
of styrene was > 99% and the regioselectivity for linear and
branched esters was 83% and 12%, respectively (Scheme 1d).
By using different supports (CeO2 (nanoparticle), CeO2-rod, and
CeO2-cube), three catalysts including Ru-clusters/CeO2,
Ru/CeO2-rod, and Ru/CeO2-cube were prepared and applied in
this reaction. Structural characterizations demonstrate that the
L/B ratio is related to the Ru size of supported Ru catalysts.
Raman characterization and NH3-TPD results show that the Ru
size has a great relationship with the metal-support interaction
and the concentration of oxygen vacancy of the catalyst. The
highest regioselectivity of linear ester could be obtained using
Ru-clusters/CeO2 as catalyst owing to the smallest size of Ru
clusters on the CeO2 surface.
Initially, hydromethoxycarbonylation of styrene was con-
ducted under 0.5 MPa of CO in methanol at 165 °C for 6 h.
When Ru-clusters/CeO2 was used as the catalyst, the conver-
sion of styrene was 43% with 82% and 13% regioselectivity of
linear and branched ester, respectively (Table 1, entry 1). The
reaction did not take place in the absence of catalyst or only in
the presence of CeO2 support (Table 1, entries 2–3). In compar-
ison, RuCl3·nH2O, the Ru precursor of Ru-clusters/CeO2, gave
very low regioselectivity of total ester (L/B = 36:6), albeit >
99% conversion of styrene (Table 1, entry 4). Other metals
including Pd and Rh exhibited no activities at all (Table 1, en-
tries 5–6). Both a low conversion of styrene (7%) and poor
regioselectivity of 61:21 (L/B) were obtained when Ru/SiO2
was used as the catalyst (Table 1, entries 7).
Further experiments optimizing of the reaction conditions
to improve catalytic activity were conducted (Fig. 1). First, we
investigated the influence of CO pressure on styrene hydro-
methoxycarbonylation catalyzed by Ru-clusters/CeO2 (Fig. 1a).
Obviously, when the CO pressure increased from 0.1 to 0.9
MPa, the conversion of styrene decreased from 87% to 43%.
The regioselectivity of linear ester remained at 82% (L/B =
82:12). Therefore we chose 0.5 MPa as the optimizing pressure
of CO, in which condition both a moderate conversion of sty-
rene (51%) and high regioselectivity of 82:12 (L/B) could be
obtained. Further optimization of the reaction temperature
under 0.5 MPa of CO was conducted (Fig. 1b). The catalytic
results at temperatures of 145–185 °C showed that the conver-
sion of styrene increased rapidly from 4% at 145 °C to 51% at
165 °C and then to 80% at 185 °C. The regioselectivity of 29:14
(L/B) obtained at 145 °C increased to 82:12 (L/B) at 165 °C
and then decreased to 66:11 (L/B) at 185 °C. Thus the temper-
Table 1
Hydromethoxycarbonylation of styrene.
Product distribution (%)
Conversion of
styrene (%)
Entry
Catalyst
L
82
B
13
Others
5
1
2
3
4
5 a
6
7
Ru-clusters/CeO2
no catalyst
CeO2
RuCl3·nH2O
Pd/CeO2
43
< 2
< 2
> 99
15
trace
trace
36
trace
trace
6
trace
trace
58
trace
trace
61
trace
trace
21
99
trace
8
Rh/CeO2
Ru/SiO2
< 2
7
Reaction conditions: catalyst (0.1 g), styrene (0.5 mmol), methanol (4
mL), CO (0.9 MPa), 165 °C, 6 h. Conversion is determined by GC using
mesitylene as an internal standard. CeO2: CeO2 nanoparticle. Other
products are ethylbenzene and polystyrene. L: linear ester. B: branched
ester. a The product is ethylbenzene.
Scheme 1. Synthesis of esters via hydroalkoxycarbonylation of olefins.
Homo: homogeneous catalyst; Heter: heterogeneous catalyst.

Jinghua An et al. / Chinese Journal of Catalysis 41 (2020) 963–969
965
Fig. 1. (a) Effect of CO pressure on hydromethoxycarbonylation of styrene catalyzed by Ru-clusters/CeO2. Reaction conditions: Ru-clusters/CeO2 (0.1
g), methanol (4 mL), 165 °C, 6 h. Other products are ethylbenzene and polystyrene. (b) Effect of reaction temperature on styrene hydromethoxycar-
bonylation catalyzed by Ru-clusters/CeO2. Reaction conditions: Ru-clusters/CeO2 (0.1 g), methanol (4 mL), CO (0.5 MPa), 6 h. (c) Time-on-stream
profile at 165 °C. Reaction conditions: Ru-clusters/CeO2 (0.1 g), methanol (4 mL), CO (0.5 MPa), 165 °C. (■) Conversion of styrene, (●) Regioselectivity
of linear ester, (▲) Regioselectivity of branched ester, () Others.
ature of 165 °C was considered to be the optimal temperature
for the reaction. Further extending the reaction time to 14 h
under 0.5 MPa of CO at 165 °C, the conversion of styrene in-
creased to > 99%, giving 83% and 12% regioselectivity of line-
ar and branched ester, respectively (Fig. 1c).
Mechanism investigations for styrene hydromethoxycar-
bonylation over Ru-clusters/CeO2 were then conducted (Fig. 2).
Fig. 2a shows the plot of the logarithm of the rate constants
log(kX/kH) plotted against Brown-Okamoto constant σp for each
substituent on para-position in styrene (CH3, H, F, or Cl). Obvi-
ously, there was no linear relationship between log(kX/kH) and
σp, implying that the reaction is not sensitive to groups substi-
tuted on styrene [25]. Meanwhile, this result suggested the
radical path of the reaction. Then further experiment using
TEMPO (2,2,6,6-tetramethylpiperidine-N-oxide) as the radical
inhibitor was conducted and the conversion of styrene de-
creased from 43% to 9% when 0.2 mmol of TEMPO was added
into the reaction system, proving the radical path of hydro-
methoxycarbonylation of styrene over Ru-clusters/CeO2 (Fig.
2b) [26,27].
The reaction kinetic of styrene hydromethoxycarbonylation
was studied at temperatures of 145–175 °C (Fig. 3a). The con-
centration of methanol, CO, and catalyst remained constant
during the reaction, maintaining the dependence of the rate on
Fig. 2. Reaction mechanism investigations of hydromethoxycarbonylation of styrene over Ru-clusters/CeO2. (a) Hammett plot, σp was obtained from
the literature [24]. Reaction conditions: Ru-clusters/CeO2 (0.1 g), styrene or its derivative (0.5 mmol), methanol (4 mL), CO (0.5 MPa), 165 °C, 3 h. (b)
The effect of the introduction of TEMPO. Reaction conditions: Ru-clusters/CeO2 (0.1 g), styrene (0.5 mmol), methanol (4 mL), CO (0.9 MPa), 165 °C, 6
h. Other products are ethylbenzene and polystyrene.

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Jinghua An et al. / Chinese Journal of Catalysis 41 (2020) 963–969
catalyst. A further higher regioselectivity of 82:13 (L/B) was
achieved when Ru-clusters/CeO2 was used as the catalyst. In
order to show the difference of the regioselectivities over the
three catalysts, L/B ratios were calculated and showed in Fig.
4b. The order of L/B ratios was in
a subsequence of
Ru-clusters/CeO2 (6.92) Ru/CeO2-rod (3.75) > Ru/CeO2-cube
(3.14) (Fig. 4b), which means that the highest L/B ratio was
obtained when Ru-clusters/CeO2 was used as catalyst.
To elucidate the reasons for observed different L/B ratios
obtained in hydromethoxycarbonylation of styrene over the
three catalysts, we first characterized their structures using
electron microscopy. Both high-angle annular dark-field imag-
ing-transmission electron microscope (HADDF-STEM) and
energy-dispersive X-ray spectroscopy (EDX) using the Ru L line
confirmed that the highly-dispersed Ru clusters existed on the
defected CeO2 surface for Ru-clusters/CeO2 (Fig. 5a and 5b).
However, a small amount of Ru nanoparticles with most of Ru
clusters could be observed on the surface of Ru/CeO2-rod cata-
lyst based on the characterizations from HADDF-STEM and
EDX mappings using the Ru L line (Fig. 5c and 5d). The TEM
and HR-TEM characterizations showed that a large number of
Ru nanoparticles unevenly distributed on CeO2-cube surface
(Fig. 5e).
By combining the different Ru sizes and the L/B ratios ob-
tained in styrene hydromethoxycarbonylation over the three
catalysts, we found that the L/B ratio is related to the Ru size of
supported Ru catalysts. The Ru-clusters/CeO2, who has the
smallest Ru size on CeO2 surface, gave the highest L/B ratio in
hydromethoxycarbonylation of styrene.
Considering the fact that metal-support interaction between
metal and their oxide supports has profound effects on the
dispersion and size of metal species in heterogeneous catalysts,
the metal-support interaction for the three catalysts was then
investigated via Raman characterization (Fig. 6a) [32–38]. The
Fig. 3. (a) Kinetic analysis of styrene hydromethoxycarbonylation at (
175 °C, (■) 165 °C, (●)155 °C, and (▲) 145 °C using Ru-clusters/CeO2
catalyst. (b) Arrhenius plot using the data in (a). Reaction conditions:
Ru-clusters/CeO2 (0.1 g), styrene (0.5 mmol), methanol (4 mL), CO (0.5
MPa).
styrene to be isolated. The k values at 175, 165, 155, and 145 °C
were 11.5 × 10–6, 7.5 × 10–6, 4.5 × 10–6, and 5.6 × 10–6, respec-
tively, which were calculated from the slopes of the plots in Fig.
3a. Obviously, there was a linear Arrhenius plot of ln(k) versus
1000/T (Fig. 3b). And the activation energy (Ea) was calculated
to be 48.50 kJ mol–1, indicating the smoothly proceeding of
styrene hydromethoxycarbonylation over heterogeneous
Ru-clusters/CeO2 catalyst.
In order to investigate the factors influencing the regioselec-
tivity of styrene hydromethoxycarbonylation, three catalysts
including Ru-clusters/CeO2, Ru/CeO2-rod, and Ru/CeO2-cube
were prepared by the same method [28,31]. And then the three
catalysts were applied in the hydromethoxycarbonylation of
styrene under the same reaction conditions (Fig. 4a). When
Ru/CeO2-cube was used as the catalyst, the regioselectivity of
66:21 (L/B) was obtained. The reaction proceeded in higher
regioselectivity of 75:20 (L/B) when Ru/CeO2-rod was used as
7
6
5
4
3
2
1
0
(a)
(b)
Product yield (%)
Catalyst
L
B
5
Others
Ru/CeO2-cube
Ru/CeO2-rod
15
37
71
3
2
4
10
11
Ru-clusters/CeO2
Ru/CeO2-cubeRu/CeO2-rodRu-clusters/CeO2
Fig. 4. (a) The catalytic performance of Ru-clusters/CeO2, Ru/CeO2-rod, and Ru/CeO2-cube on hydromethoxycarbonylation of styrene. Reaction con-
ditions: catalyst (0.1 g), methanol (4 mL), CO (0.5 MPa), 165 °C, 12 h. Other products are ethylbenzene and polystyrene. (b) The L/B ratios obtained in
Fig. 4a.

Jinghua An et al. / Chinese Journal of Catalysis 41 (2020) 963–969
967
ports.
In the literature reports, the formation of metal size has a
great relationship with the concentration of oxygen vacancy,
which presents a linear relationship with the concentration of
acid site [40,45]. Thus, we turned to characterize
Ru-clusters/CeO2, Ru/CeO2-rod, and Ru/CeO2-cube using
NH3-TPD to investigate the concentration of acid site of the
catalyst (Fig. 6b). Obviously, the order of acid concentration of
the three catalysts was in the subsequence of Ru-clusters/CeO2
> Ru/CeO2-rod > Ru/CeO2-cube (Table S1). Thus, the order of
the concentration of oxygen vacancy was in the subsequence of
Ru-clusters/CeO2 > Ru/CeO2-rod > Ru/CeO2-cube (Fig. 6c).
Therefore, the smallest size of the Ru with the highest concen-
tration of oxygen vacancy, having the largest steric hindrance,
is favor to the linear adsorption mode of styrene, which is ben-
efit to generation of linear product. Similar results are also re-
ported before [46].
In summary, Ru-clusters/CeO2 is used as an active catalyst
for the hydromethoxycarbonylation of styrene with > 99%
conversion of styrene, giving 83% and 12% regioselectivity of
linear and branched ester, respectively. Structural characteri-
zations demonstrate that the L/B ratio is related to the Ru size
of supported Ru catalysts. Further Raman characterization and
NH3-TPD demonstrate that the metal-support interaction and
the concentration of oxygen vacancy of the catalyst have a great
influence on Ru size. Mechanism investigation proves the radi-
cal path of hydromethoxycarbonylation of styrene over
Ru-clusters/CeO2. Considering the complication varying of
CeO2 shape, further research work, in-depth investigating of the
factors affecting regioselectivity, is ongoing.
Fig. 5. (a) Combining HAADF-STEM image and EDX elemental mapping
of Ru-clusters/CeO2. (b) EDX elemental mapping of Ru-clusters/CeO2.
(c) HAADF-STEM images of Ru/CeO2-rod. (d) EDX elemental mapping
of Ru/CeO2-rod. The inset shows an enlargement of the Ru nanoparticle
indicated by white arrow. (e) The TEM and HR-TEM images of
Ru/CeO2-cube.
results are given in Fig. 6a and show that the Ru-clusters/CeO2,
Ru/CeO2-rod, and Ru/CeO2-cube exhibited a strong peak at 453
cm–1 and a relative weaker peak at 595 cm–1, corresponding to
the vibration model of octahedral local symmetry around CeO2
lattice and the defect-induced modes of CeO2, respectively
[39–43]. Besides the two peaks of CeO2, two peaks at 695 and
980 cm–1 were also observed for Ru-clusters/CeO2 and
Ru/CeO2-rod, which could be assigned to Ru–O–Ce bond re-
sulting from the stronger interaction between Ru species and
the different supports (CeO2 and CeO2-rod) [44]. However, no
peaks at 695 and 980 cm–1 were observed in Ru/CeO2-cube,
indicating a weak interaction exists between Ru species and
CeO2-cube. Thus, the Raman characterization showed that
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Jinghua An et al. / Chinese Journal of Catalysis 41 (2020) 963–969
Graphical Abstract
Chin. J. Catal., 2020, 41: 963–969 doi: S1872-2067(19)63527-8
Linear-regioselective hydromethoxycarbonylation of styrene
using Ru-clusters/CeO2 catalyst
Jinghua An, Yehong Wang, Zhixin Zhang, Jian Zhang, Martin Gocyla,
Rafal E. Dunin-Borkowski, Feng Wang *
Dalian Institute of Chemical Physics, Chinese Academy of Sciences;
China; University of Chinese Academy of Sciences, China;
Ernst Ruska Centre for Microscopy and Spectroscopy with Electrons
and Peter Grünberg Institute, Germany
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Ru/CeO2催化剂催化苯乙烯氢甲氧基羰基化反应高选择性制备直链酯类化合物
安静华a,b, 王业红a, 张志鑫a, 张 健a, Martin Gocyla c, Rafal E. Dunin-Borkowski c, 王 峰a,*
a中国科学院大连化学物理研究所, 洁净能源国家实验室, 生物能源研究部, 辽宁大连116023
b中国科学院大学, 北京100049
c厄恩斯特·鲁斯卡电子显微与光谱学中心和彼得·格伦伯格研究所, 尤利希52425, 德国
摘要: 酯类化合物在工业上具有广泛应用, 例如可用于合成香水、调味剂(味精)、洗涤剂和表面活性剂等. 其中, 烯烃的氢
烷氧基羰基化反应是一种合成酯类化合物的重要方法, 其低消耗、100%的原子经济性和原料的易获得等优势使其在制备
酯类化合物中成为一个有效且实际可行的方法. 对于该反应, 文献多采用Pd或Rh的络合均相催化剂, 其中控制反应过程中
直链酯类化合物(L)和支链酯类化合物(B)的选择性是一项颇具挑战性的课题. 虽然目前可通过配体的设计和修饰来调节,
但多集中在均相催化体系, 因此在选择性调变方面的研究仍很欠缺. 相对于均相催化, 多相催化由于产物易分离和提纯、
催化剂可循环使用等优势而逐渐引起了研究者的广泛关注. 在多相催化体系中, Pd负载在强酸性树脂作为催化剂已被应
用于苯乙烯氢甲氧基羰基化反应, 但在该反应中支链酯类化合物为主要产物. 因此, 寻找一个可有效改善多相反应体系中
选择性问题的方法是非常有意义的.
在本研究工作中, 我们分别以CeO2纳米颗粒(NP)、CeO2纳米棒(Rod)和CeO2纳米立方体为载体, 利用浸渍法制备了
Ru/CeO2、Ru/CeO2-rod和Ru/CeO2-cube三种催化剂, 并进一步用于苯乙烯氢甲氧基羰基化反应. 探究了CO压力、反应温度
和反应时间对三种催化剂催化苯乙烯氢甲氧基羰基化反应的影响. 结果表明, Ru/CeO2作为多相催化剂催化苯乙烯氢甲氧
基羰基化反应时, 苯乙烯选择性高于99%, 直链酯选择性为83%, 支链酯选择性为12%. 机理研究表明, 该反应为自由基机
理. 动力学分析表明, 该反应的反应活化能为48.50 kJ mol–1. 结合三种催化剂的反应活性以及HRTEM结构表征结果可知,
该反应中L/B比值与Ru的尺寸有较大关系. 进一步的拉曼表征和NH3-TPD表征结果证明, Ru的尺寸与金属-载体之间的相
互作用以及催化剂表面的氧空位浓度有直接关系.
关键词: 选择性; 钌/二氧化铈; 酯类化合物; 氢甲氧基羰基化反应; 烯烃; 多相催化
收稿日期: 2019-10-31. 接受日期: 2019-12-18. 出版日期: 2020-06-05.
*通讯联系人. 电话/传真: (0411)84379798; 电子信箱: wangfeng@dicp.ac.cn
基金来源: 中国科学院战略性先导科技专项(XDB17020300); 国家自然科学基金(21721004, 21690084, 21690080).
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).