Catalytic upgrading of ethanol to butanol over a binary catalytic system of FeNiOx and LiOH

Article abstract of DOI:10.1016/S1872-2067(20)63541-0

Catalytic conversion of ethanol to butanol is vital to bridge the gap between huge amounts of ethanol production, the limited blending ratio of ethanol in gasoline, and the outstanding performance of butanol. In this work, a highly active binary catalytic system of FeNiO_x and LiOH was developed for upgrading of ethanol to butanol. After 24 h reaction at 493 K, the selectivity to butanol reached 71% with >90% high carbon alcohols at 28% ethanol conversion, which was comparable to the performance of some noble metal homogeneous catalysts.

Full text of DOI:10.1016/S1872-2067(20)63541-0

Chinese Journal of Catalysis 41 (2020) 672–678
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
Catalytic upgrading of ethanol to butanol over a binary catalytic
system of FeNiOx and LiOH
Jifeng Pang a, Mingyuan Zheng a,*, Zhinuo Wang a,b, Shimin Liu b, Xinsheng Li a,c, Xianquan Li a,c,
Junhu Wanga,d, Tao Zhang a,#
a CAS Key Laboratory of Science and Technology on Applied Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023,
Liaoning, China
b School of Materials Science and Engineering, Dalian Jiaotong University, Dalian 116028, Liaoning, China
c University of Chinese Academy of Sciences, Beijing 100049, China
d Mössbauer Effect Data Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
A R T I C L E I N F O
A B S T R A C T
Article history:
Catalytic conversion of ethanol to butanol is vital to bridge the gap between huge amounts of etha-
nol production, the limited blending ratio of ethanol in gasoline, and the outstanding performance of
butanol. In this work, a highly active binary catalytic system of FeNiOx and LiOH was developed for
upgrading of ethanol to butanol. After 24 h reaction at 493 K, the selectivity to butanol reached 71%
with >90% high carbon alcohols at 28% ethanol conversion, which was comparable to the perfor-
mance of some noble metal homogeneous catalysts.
Received 24 October 2019
Accepted 23 November 2019
Published 5 April 2020
Keywords:
Ethanol
Catalysis
© 2020, Dalian Institute of Chemical Physics, Chinese Academy of Sciences.
Published by Elsevier B.V. All rights reserved.
Butanol
Hydrogen transfer
Condensation
The fossil oil depletion and environmental issues have stim-
ulated the exploration of renewable fuels [1,2]. Ethanol is the
most promising biofuel to partially replace the conventional
gasoline thanks to the well-established sugar fermentation
processes and the developed catalytic methods [3–6]. Its pro-
duction reached ca. 30 billion gallons in 2017 with an annual
increase of 4%–6% in the past five years [7]. Nevertheless,
ethanol has a relatively low energy density compared to gaso-
line (19.6 MJ/L vs 32 MJ/L), and the mixed ratio of ethanol in
gasoline is confined to < 15 v%. Additionally, ethanol readily
absorbs water under most conditions, not only causing the
separation and storage trouble in the existing fuel infrastruc-
tures, but also inducing corrosion problems to the current en-
gines of vehicles [8]. In contrast, butanol has a higher energy
density close to gasoline (29.2 MJ/L), and is immiscible with
water and noncorrosive to the engines. These improved fea-
tures endow it a promising candidate to be used as an ad-
vanced fuel additive [9,10]. In spite of the progress in ABE (ac-
etone-butanol-ethanol) fermentation, the synthesis of butanol
from renewable feedstocks remains a challenge due to the
self-inhibition of butanol (1%–3%) [11]. Considering the great
amount of ethanol production and the excellent performance of
* Corresponding author. Tel: +86-411-84379738; Fax: +86-411-84685940; E-mail: myzheng@dicp.ac.cn
# Corresponding author. E-mail: taozhang@dicp.ac.cn
This work was supported by the National Natural Science Foundation of China (21690081, 21690084, 21776268, and 21721004), and the Strategic
Priority Research Program of Chinese Academy of Sciences (XDA 21060200). We also thank Alexandre I. Rykov for the Mössbauer spectrum charac-
terization and data analysis.
DOI: 10.1016/S1872-2067(20)63541-0 | http://www.sciencedirect.com/science/journal/18722067 | Chin. J. Catal., Vol. 41, No. 4, April 2020

Jifeng Pang et al. / Chinese Journal of Catalysis 41 (2020) 672–678
673
butanol, it is highly attractive to upgrade ethanol into butanol
[12–15].
The catalytic conversion of ethanol to butanol is a multiple
Table 1
Catalytic conversion of ethanol over different heterogeneous catalystsa.
Selectivity b (%)
EA Butanol C6
Conver-
sion (%)
Entry
Catalyst
step reaction, known as the Guerbet reaction [16,17]. In gen-
eral, ethanol is first dehydrogenated to acetaldehyde, and then
to acetaldol via the aldol condensation. After the dehydration
and hydrogenation reactions, butanol is formed eventually. A
variety of catalysts have been developed for this reaction [18].
Homogeneous catalysts of Ru, Ir, and Mn complexes were used
to convert ethanol into butanol in the presence of different
bases and ligands [19–23]. The Ru or Ir complexes participate
in the dehydrogenation and hydrogenation reactions, and the
base or some non-noble hydroxide complexes catalyze the al-
dol condensation of acetaldehyde to C4 products. By precisely
controlling the micro reaction environment, the butanol selec-
tivity reached > 99% with ca. 30% ethanol conversion at 423 K
in the presence of different additives [21]. On the other hand,
recyclable heterogeneous catalysts of hydroxyapatite [24,25],
mixed oxides [26,27]and metal based catalysts [28–32] have
been widely exploited for ethanol conversion. However, it is
still a challenge to balance the ethanol conversion and butanol
selectivity for the heterogeneous catalysts. In most cases, the
selectivity to butanol is lower than 60% at > 20% ethanol con-
versions. The reason lies in the uncontrollable distribution and
strength of acid and base sites in different reaction conditions,
which cause serious side reactions to produce methane, eth-
ylene, ethyl acetate, butyraldehyde and >C10 carbon alcohols.
Recently, binary catalysts were developed to combine the ad-
vantages of homogeneous and heterogeneous catalysts. For
instance, Zhang et al. [33] employed commercial cobalt pow-
ders and NaHCO3 for converting ethanol to butanol at 473 K in
aqueous solution. The selectivity to butanol reached 69%, but
unfortunately the ethanol conversion was less than 10% with a
very low reaction efficiency (3–20 d reaction). Therefore, it is
highly desirable to explore more efficient and reusable catalytic
systems to reach the high ethanol conversion and butanol se-
lectivity. Herein, a novel binary catalytic system of FeNiOx and
LiOH was first developed for the conversion of ethanol to bu-
tanol. The butanol selectivity reached > 70% at 28% ethanol
conversion under the optimal reaction conditions of 493 K for
24 h (butanol productivity: 0.33 g h–1 gcat–1). The FeNiOx played
the key role in hydrogen transfer reaction, while the LiOH cat-
alyzed the aldol condensation reaction and also enhanced eth-
anol conversion due to the synergistic effect with FeNiOx. The
FeNiOx catalyst was rather stable, and able to be used for seven
times without deactivation.
AA
C8
1 c
2
3
4
5
NiOx
CuOx
FeNiOx
5%Ru/C
5%Pd/C
4.6
4.4
4.8
3.2
3.4
3.1
4.1
3.0
6.7 12.5
24.7
0.1 10.5
53.0
52.5
68.3
35.0
35.7
42.4
31.6
64.7
4.8 0.6
1.6 0.1
0
10.1 1.9
10.2 3.5
12.7 5.1
14.0 6.1
15.5 7.8
13.1 3.2
8.2
6.6
5.7
5.8
4.2
0
6
7
2%Rh/TiO2
5%Ni/CeO2
4%Ir4%Ni/MC
7.4
1.0
8
10.7
3.1
a Reaction conditions: 30 mL ethanol, 0.3 g catalyst and 0.2 g NaHCO3 in
b
50 mL autoclave, 0.5 MPa N2, 473 K for 24 h. AA, EA, C6 and C8 are
abbreviations for acetaldehyde, ethyl acetate, six carbon alcohols, and
eight carbon alcohols, respectively. Gaseous products of methane,
carbon monoxide, and carbon dioxide were detected with overall yield
of 10.3%.
c
tion reaction of acetaldehyde [30,34]. In contrast, over the
FeNiOx catalyst, the butanol selectivity reached 68.3% with
more than 80% overall high carbon alcohols at the same etha-
nol conversion. The main by-product is ethyl acetate (10.5%)
with decreased gaseous products, which endows it as the
promising catalyst for ethanol conversion. From the results of
XRD and XRF (Fig. S1 and Table S1), the FeNiOx catalyst is
composed of FeNi oxides (possible phases are NiFe2O4,
Fe1.85Ni1.25O4, Fe3O4, and a small amount of metallic Fe, Ni, or
FeNi alloy) with the Fe/Ni ratio of 4:1. Different supported
metal catalysts were also used for this reaction. As shown in
entries 4–7, the butanol selectivities were less than 43% at ca.
3% ethanol conversions over the Ru/C, Pd/C, Rh/TiO2, and
Ni/CeO2 catalysts, which also gave a low carbon balance in the
reaction due to by-products. NiIr/MC (meso porous carbon)
catalyst was tried in this reaction (entry 8) due to its high activ-
ity in the hydrogenation reaction as we previously reported
[35]. Although the catalyst demonstrated high selectivity to
butanol (64.7%), the low ethanol conversion and the scarcity of
noble metal stimulated us to employ cheap and readily availa-
ble FeNiOx catalysts for ethanol upgrading.
Liquid or solid base/salt catalysts are widely used for the
aldol condensation reaction, and the base types, strength or
strength distributions greatly influence the final product selec-
tivity [17,36,37]. Therefore, besides the benchmark salt of Na-
HCO3, different salts or bases with same weight ratio were
tested for ethanol conversion in the presence of FeNiOx cata-
lysts under mild reaction conditions. As shown in Fig. 1, the
butanol selectivities were less than 60% over the alkali metal
carbonates, following an order of Na>Cs>Li>K. Differently, the
main product shifts to ethyl acetate with lower ethanol conver-
sion when using the alkaline earth metal carbonates like CaCO3
and BaCO3 in the reaction. The selectivity to butanol over CaCO3
is much lower than that of metal oxide such as CaO, indicating
that suitable base sites are needed to balance the ethanol de-
hydrogenation and aldol condensation reactions. Following the
strategy of homogeneous catalysts, C2H5ONa was tested for
ethanol conversion in combination with FeNiOx. It gave 54.9%
butanol selectivity at 9.4% ethanol conversion, being more
Dehydrogenation is the first and foremost reaction step for
the one-pot conversion of ethanol to butanol. To activate the
ethanol, a variety of metal catalysts were screened in the pres-
ence of NaHCO3. As shown in Table 1, entries 1–3, the selectivi-
ty to butanol reached ca. 53.0% at 4.4%–4.6% ethanol conver-
sions over the NiOx and CuOx catalysts (the XRD patterns are
shown in Fig. S1). Large amounts of gaseous products (me-
thane, carbon monoxide, and carbon dioxide; ca. 10.3% carbon
yield) and ethyl acetate were observed over the NiOx and CuOx
catalysts, respectively. This should be attributed to the random
cleavage of C–C bonds in ethanol and excessive dehydrogena-

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Jifeng Pang et al. / Chinese Journal of Catalysis 41 (2020) 672–678
0.2–0.6 g, and decreased to 23.2% with 0.8 g LiOH. The butanol
100
75
50
25
0
12
8
Octanol
Hexanol
selectivity first increased and then levelled off at around 71%
with LiOH amount increase. In contrast, the yield of ethyl ace-
tate gradually decreased as increasing the LiOH amount. The
base sites are crucial to the aldol condensation reaction. At low
base loadings, the ethanol was preferentially transformed to
ethyl acetate due to the further conversion of acetaldehyde
over the FeNiOx catalyst. The presence of abundant base sites
promoted the condensation reaction, and shifted the reaction
equilibrium to butanol with elevated ethanol conversion.
However, the excessive base sites changed the interaction be-
tween ethanol and FeNiOx, and inhibited the ethanol activation.
It is worth noting that this reaction has a wide catalyst opera-
tion window. At the FeNiOx and LiOH weight ratio of 0.5–1.5,
the butanol selectivity reached 71% with > 90% high carbon
alcohols at 28% ethanol conversion. Additionally, the ethanol
conversion, butanol selectivity, and high carbon alcohols selec-
tivity are comparable to the homogeneous catalysts results (in
autoclave), and far higher than the results of most heterogene-
ous catalysts [22].
The effect of reaction temperature (473–523 K) and reac-
tion time (4–50 h) on ethanol conversion and high carbon al-
cohols selectivity were investigated. As shown in Fig. 3(A), the
ethanol conversion was 13.2% with 77.9% selectivity to buta-
nol at 473 K over the optimized FeNiOx (0.3 g) and LiOH (0.3 g)
catalysts. The ethanol conversion was linearly increased to
43.5% as increasing the reaction temperatures to 523 K. The
butanol selectivity levelled off 75% at temperatures between
473 and 503 K, and then decreased dramatically to 44.2% and
28.9% at 513 and 523 K, respectively. Large amounts of gase-
ous products were detected due to the decomposition of prod-
ucts or intermediates at higher temperatures. Fig. 3(B) depicts
the effect of reaction time on the butanol yield. Prolonging the
reaction time improved the butanol yield to ca. 19.0% after the
24 h reaction (butanol productivity reached 0.33 g h–1 gcat–1),
and then remained constant in the time range of 24–50 h. The
ethanol conversion kept increasing in the whole time range, but
the butanol selectivity was as high as ca. 72% in 24 h, and then
gradually decreased to 40.2% in the 50 h reaction. The butanol
product is metastable, and able to be decomposed to methane
and carbon oxides. It also serves as the reaction feedstock for
the further aldol condensation to produce higher carbon alco-
hols (> C10). To get a high butanol yield, the reaction tempera-
ture and reaction time were optimized to 493 K and 24 h, re-
spectively.
Butanol
Ethyl acetate
Acetaldehyde
4
0
Fig. 1. Catalytic conversion of ethanol over different additives in the
presence of FeNiOx. Reaction conditions: 30 mL ethanol, 0.3 g FeNiOx
with 0.2 g additive in 50 mL autoclave, 0.5 MPa N2, 473 K for 24 h;
NaOH* indicates the amount of NaOH is 0.33 g, equal to the mole of
LiOH.
efficient than the above mentioned salts and bases. Afterwards,
hydroxide bases were tested in ethanol conversion. Over
Mg(OH)2 and NaOH, low ethanol conversion (<3%) with ca.
30% selectivity to butanol were obtained. Interestingly, LiOH
significantly improved the ethanol conversion to 11.2% with
56.1% selectivity to butanol, even much higher than that over
the C2H5ONa or NaOH at the same mole of LiOH. In accordance
with previous results about the high activity of Li based cata-
lysts in condensation reactions [38–40], LiOH herein provided
the base sites to promote both aldol condensation and ethanol
dehydrogenation reactions, and afforded the elevated butanol
yield. Therefore, the binary catalyst of FeNiOx and LiOH was
identified as the optimal candidate for the further study in the
following sections.
To balance the rates of dehydrogenation and aldol conden-
sation reactions, the amounts of metal and base catalysts were
optimized. As shown in Fig. 2, the amount of LiOH greatly af-
fected the ethanol conversion and butanol selectivity. As the
amount of LiOH increased from 0.05 g to 0.2 g, the ethanol
conversion gradually increased, and maximized to ca. 28%.
Then, the ethanol conversion remained constant in the range of
80
60
40
20
0
30
25
20
15
10
5
Acetaldehyde
Ethyl acetate
Butanol
Hexanol
Octanol
The stability of the FeNiOx catalyst was evaluated. As shown
in Fig. 4, the initial butanol selectivity was 75% at 29.1% etha-
nol conversion. After four cycles running, the butanol selectivi-
ty still reached 72% at 25% ethanol conversion. The ethanol
conversion was slightly decreased with the run number in-
crease. Then, the FeNiOx was reduced by NaBH4 after the fourth
run and then used for further cycle experiments. After the re-
duction, the butanol selectivity reached 71% and the ethanol
conversion kept at 24%–25% in the following four cycles. The
slightly decrease in ethanol conversion should be attributed to
the surface oxidation and physical loss of fine FeNiOx particles
during the recycle procedures. The XRD patterns and surface
0
0.0
0.2
0.4
0.6
0.8
Weight /%
Fig. 2. Effect of LiOH amounts on ethanol conversion and product dis-
tribution. Reaction conditions: 30 mL ethanol, 0.3 g FeNiOx, 50 mL au-
toclave, 0.5 MPa N2, 493 K, 24 h.

Jifeng Pang et al. / Chinese Journal of Catalysis 41 (2020) 672–678
675
100
75
50
25
0
50
40
30
20
10
0
100
75
50
25
0
60
40
Butanol
Hexanol
Octanol
B
A
Con. /%
Octanol
Hexanol
Butanol
YieldButanol /%
20
0
470
480
490
500
510
520
530
0
10
20
30
40
50
Temperature /K
Time /h
Fig. 3. Effect of reaction temperature (A, 24 h) and time (B, 493 K) on ethanol conversion and product distribution. Reaction conditions: 30 mL etha-
nol, 0.3 g FeNiOx, 0.3 g LiOH, 0.5 MPa N2, 50 mL autoclave.
area of the FeNiOx catalyst before and after reaction are shown
in Fig. S1 and Fig. S2, which demonstrated the same phases and
structures before and after reaction. The SEM and TEM images
of FeNiOx before and after reaction were shown in Fig. S3. The
FeNiOx catalysts had identical layer structures with thickness of
30–60 nm before and after reaction. These results indicate that
the FeNiOx is rather stable under reaction conditions. Addition-
ally, the FeNiOx is conveniently to be recovered from the reac-
tion solution by the magnetic separation method, as shown in
Fig. S4. For LiOH, it was recovered after the removal of alcohols
by the distillation method. Based on the XRD patterns of LiOH
before and after reaction in Fig. S5 and the reaction results in
Fig. S6, one can find that the LiOH is also very stable, which can
be directly reused in this reaction for three times. During the
reaction, less active salt of Li2CO3 formed, which decreased the
ethanol conversion to some extent. However, the LiOH can be
regenerated through the calcination process, indicating the
recyclable of LiOH in this reaction.
Table S2. The isomer shift (IS) of Fe3O4 (octa) was 0.63 mm/s,
much higher than the pure Fe3O4 (octa, 0.56 mm/s) in the liter-
ature [41–43], indicating the presence of Ni2+ in the Fe3O4
phase. Additionally, about 11.9% of metallic Fe was detected,
which was nearly invisible in the XRD due to its high dispersion
and the formation of FeNi alloy [44,45]. It is generally accepted
that the hydrogen transfer is crucial to the ethanol to butanol
process [46]. The presence of metallic Fe, Fe2+, and Fe3+ pro-
vides the feasibility of multiple sites for ethanol dehydrogena-
tion, hydrogen storage, and hydrogenation. This conjecture is
confirmed by the XPS results in Fig. S7. Different Fe species
including Fe2O3, Fe3O4, and Fe were detected (Fig. S7, A) along
with NiFe2O4 and Ni2O3 species (Fig. S7, B) over the FeNiOx
catalyst. From the results of H2-TPR and TPD experiments (Fig.
S8), although negligible metallic Ni and Fe was observed by
XRD and XPS, the great hydrogen consumption at 420–571 K in
Fig. S8(A) indicating the presence of metallic Ni and Fe under
reaction conditions (493 K in ethanol, vs 420–571 K for reduc-
tion in H2-TPR). Additionally, strong hydrogen adsorption was
found over the FeNiOx catalyst during the wide desorption
window (500 to 750 K) in Fig. S8(B), indicating the strong in-
teraction of hydrogen and the FeNiOx catalyst for the hydrogen
transfer reaction.
To identify and quantify the iron phases in FeNiOx, 57Fe
Mössbauer spectrum was collected after reaction with ethanol
protection. As shown in Fig. 5, the spectrum was fitted by three
sextets, corresponding to the main phase of Fe3O4 (octa, blue
line, 60%), Fe3O4 (tetra, red line, 28.1%) and Fe0 (green line,
11.9%). The corresponding spectral parameters were given in
To disclose the reaction mechanism of the binary catalytic
system in ethanol conversion, some conditional experiments
were conducted. As shown in Fig. 6, dehydrogenation products
100
Octanol
Hexanol
Butanol
30
20
10
0
75
50
25
0
0
2
4
6
8
Run number
-10 -8 -6 -4 -2
0
2
4
6
8
10
Velocity /mms-1
Fig. 4. Reusability of the FeNiOx catalyst. Reaction conditions: 30 mL
ethanol, 0.3 g FeNiOx, 0.3 g LiOH, 50 mL autoclave, 0.5 MPa N2, 493 K, 24
h.
Fig. 5. 57Fe Mössbauer spectrum of the FeNiOx catalyst after reaction
(protected in ethanol).

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Jifeng Pang et al. / Chinese Journal of Catalysis 41 (2020) 672–678
conversion with the butanol yield of ca. 19.0%. The FeNiOx was
efficiently transferred the hydrogen from ethanol to butanol,
and LiOH catalyzed the aldol condensation reactions and pro-
moted the ethanol conversion. The heterogeneous FeNiOx cat-
alyst was conveniently recycled by the magnetic separation
method and cycled for seven times without deactivation. The
LiOH was also recyclable, and could be regenerated by the cal-
cination process. These results make the binary catalytic sys-
tem of FeNiOx and LiOH very attractive for practical applica-
tions.
100
75
50
25
0
Octanol
Butanol
Acetaldehyde
Hexanol
Ethyl acetate
12
8
4
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Graphical Abstract
Chin. J. Catal., 2020, 41: 672–678 doi: 10.1016/S1872-2067(20)63541-0
Catalytic upgrading of ethanol to butanol over a binary catalytic
system of FeNiOx and LiOH
Jifeng Pang, Mingyuan Zheng*, Zhinuo Wang, Shimin Liu,
Xinsheng Li, Xianquan Li, Junhu Wang, Tao Zhang *
Dalian Institute of Chemical Physics, Chinese Academy of Sciences;
Dalian Jiaotong University; University of Chinese Academy of Sciences
A robust binary catalytic system of FeNiOx and LiOH was developed
for converting ethanol to butanol, over which the butanol selectivity
reached 71% with > 90% high carbon alcohols at 28% ethanol
conversion.
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FeNiOx和LiOH催化剂体系上乙醇转化到丁醇
庞纪峰a, 郑明远a,*, 王祉诺a,b, 刘世民b, 李新生a,c, 李显泉a,c, 王军虎a,d, 张 涛a,#
a中国科学院大连化学物理研究所中国科学院应用催化科学与技术重点实验室, 辽宁大连 116023
b大连交通大学材料科学与工程学院, 辽宁大连 116028
c中国科学院大学, 北京 100049
d中国科学院大连化学物理研究所穆斯堡尔谱数据中心, 辽宁大连 116023
摘要: 随着生物发酵技术的进步和化学转化方法的发展, 全球乙醇产量迅速增加. 然而, 乙醇存在能量密度低、吸水、对发
动机腐蚀性高等缺点, 其在汽油中的添加量有限, 一般低于15%, 这严重限制了乙醇产业的发展. 与此相比, 丁醇具有更高
的能量密度和汽油添加量, 是一种更加理想的油品添加剂. 因此, 乙醇催化转化为丁醇是连接高乙醇产量和优质丁醇需求
的桥梁, 具有重要的学术和应用价值. 在过去的几十年里, 均相催化剂、复合氧化物催化剂、羟基磷灰石及金属促进的氧
化物催化剂迅速发展, 但是仍存在乙醇转化率低、丁醇选择性差和催化剂不能循环等问题. 乙醇催化转化为丁醇是一个
Guerbet反应, 乙醇首先脱氢生成乙醛, 乙醛通过缩合、脱水生成巴豆醛, 巴豆醛通过加氢得到丁醇. 反应中主要涉及氢转移
活性位和羟醛缩合活性位. 因此, 本文中我们根据催化反应机理, 筛选了不同金属氧化物和碱催化剂体系, 分别用于乙醇

678
Jifeng Pang et al. / Chinese Journal of Catalysis 41 (2020) 672–678
脱氢、巴豆醛加氢和乙醛缩合、脱水反应. 结果发现, 在FeNiOx和LiOH催化体系中, 乙醇转化率和丁醇选择性最好. 通过
优化反应温度、反应时间、金属氧化物和碱量等条件, 在493 K反应釜中反应24 h, 得到28%的乙醇转化率、71%的丁醇选
择性和超过90%的C4–C8高碳醇选择性, 达到了部分均相贵金属催化剂上的反应结果. 在FeNiOx和LiOH催化体系中, FeNi-
Ox具有较强的磁性, 便于磁性分离, 循环八次后仍具有较高的催化活性, 展示出优异的稳定性. LiOH可以通过蒸馏分离, 循
环三次没有明显失活, 但有少量Li2CO3生成, 其可以通过焙烧的方式恢复. 通过穆斯堡尔谱、氢气吸附、XPS等表征和条件
实验发现, FeNiOx中存在金属态的镍、铁和不同氧化态的铁物种, 其能促进乙醇的脱氢和后续巴豆醛的加氢, 起到氢转移的
作用. LiOH具有合适的酸碱性, 能够促进乙醛的羟醛缩合, 并加速乙醇转化. 在两者协同作用下, 乙醇转化率和丁醇选择
性都有显著提高. 这一研究策略对此反应中新型催化剂的开发和反应机理的认识都具有重要的推动作用.
关键词: 乙醇; 催化; 丁醇; 氢转移; 羟醛缩合
收稿日期: 2019-10-24. 接受日期: 2019-11-13. 出版日期: 2020-04-05.
*通讯联系人. 电话: (0411)84379738; 传真: (0411)84685940; 电子信箱: myzheng@dicp.ac.cn
#通讯联系人. 电子信箱: taozhang@dicp.ac.cn
基金来源: 国家自然科学基金(21690081, 21690084, 21776268和21721004); 中国科学院战略性先导科技专项(A类)“变革性洁净能
源关键技术与示范”项目(XDA 21060200).
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).