One-pot conversion of dihydroxyacetone into ethyl lactate by Zr-based catalysts

Article abstract of DOI:10.1039/d1ra00775k

Efficient strategies for producing bio-based reagents from sustainable biomass are highly attractive for cost-effective sustainable manufacturing. In this study, a series of eco-friendly Zr-based catalysts (basic zirconium carbonate, zirconium dioxide and zirconium hydroxide) were investigated for the efficient conversion of dihydroxyacetone to ethyl lactate in a one-pot system, in which basic zirconium carbonate exhibited the best performance with 100% dihydroxyacetone conversion and 85.3% EL (ethyl lactate) yield at 140 °C, 4.0 h and 1.0 MPa N₂. The improved activity of basic zirconium carbonate could be attributed to the synergistic effect among acid and base active sites. Furthermore, this low-cost catalyst shows improved thermochemical stability and recyclability under optimal conditions, where no significant decrease in activity was observed after three runs. This catalytic process could be identified as a promising alternative to produce ethyl lactate from renewable biomass and its derivatives.

Full text of DOI:10.1039/d1ra00775k

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One-pot conversion of dihydroxyacetone into ethyl
lactate by Zr-based catalysts
Cite this: RSC Adv., 2021, 11, 10935
Junjun Shi, *a Fukun Li,*bc Jie Zhang, Ning Li, Xingmin Wang, Xianming Zhang
and Yunqi Liu
b
b
b
c
cd
Efficient strategies for producing bio-based reagents from sustainable biomass are highly attractive for
cost-effective sustainable manufacturing. In this study, a series of eco-friendly Zr-based catalysts (basic
zirconium carbonate, zirconium dioxide and zirconium hydroxide) were investigated for the efficient
conversion of dihydroxyacetone to ethyl lactate in a one-pot system, in which basic zirconium
carbonate exhibited the best performance with 100% dihydroxyacetone conversion and 85.3% EL (ethyl
ꢀ
lactate) yield at 140 C, 4.0 h and 1.0 MPa N
2
. The improved activity of basic zirconium carbonate could
Received 29th January 2021
Accepted 8th March 2021
be attributed to the synergistic effect among acid and base active sites. Furthermore, this low-cost
catalyst shows improved thermochemical stability and recyclability under optimal conditions, where no
significant decrease in activity was observed after three runs. This catalytic process could be identified as
a promising alternative to produce ethyl lactate from renewable biomass and its derivatives.
DOI: 10.1039/d1ra00775k
rsc.li/rsc-advances
biomass, which suffers from low productivity along with tedious
post-processing. Therefore, new chemo-catalytic processes from
1
. Introduction
The ever-increasing environmental pollution and energy crisis, raw biomass and its derivatives directly are intensively required.
caused by the overuse of petroleum resources, urge people to
Many studies have reported that heterogeneous solid basic
explore and utilize renewable resources. Lignocellulosic catalysts can break down C–C bond in sugars and form alkyl
biomass, the largest sustainable carbon resource, is recognized lactates (ALs). For example, a 29.45% yield of methyl lactate
ꢀ
as the most promising alternative for producing bio-fuels and (ML) was achieved from glucose under 200 C in 20 h when MgO
8
9
bio-based platform chemicals such as levulinic acid, 5-hydrox- was used. Lu et al. reported Mg-MOF-74 was an efficient
1–3
ymethyl furfural, formic acid and ethyl lactate (EL). Among catalyst for converting sucrose to ML with a yield of 47% at
ꢀ
10
them, EL obtained from biomass renery has attracted growing 220 C in 6.0 h. On the other hand, Hayashi et al. rst reported
interest due to its wide application. For example, EL could be that Lewis acid salts such as SnCl and SnCl exhibited
applied in food additives, pharmaceuticals, and cosmetics for impressively catalytic activity for the production of ALs in
2
4
11
its low toxicity. Moreover, it can also be employed as a green different alcohols. Meanwhile, Holm et al. found that Sn-beta
4,5
precursor for the synthesis of other value-added chemicals.
zeolite which contained Lewis acid sites could produce ML from
Currently, EL is produced predominantly via esterication of mono- and disaccharides. Inspired by these ndings, numerous
7
lactic acid and ethanol catalyzed by H
2
SO
4
(ref. 6) and lipase.
Lewis acid-containing solid materials have been synthesized
12
However, a number of disadvantages in this procedure should and used for the preparation of ALs, such as Sn-MCM-41, Sn-
19
13
14
15,16
17
18
be noted, such as the corrosion of reactor arising from strong MWW, Sn-Mont, SnPO,
ZrO
–TiO
,
Zr-SBA-15, ZIFs,
2
2
20
mineral acids and the catalyst recycling. Additionally, the montmorillonite-supported Pt(II) diphosphane complex and
precursor, lactic acid, is generally produced via fermentation of NiO.
21,22
The reported catalysts containing single Lewis acid or
base site are responsible for the efficient conversion of dihy-
23
droxyacetone (DHA) to lactic acid and its esters. However, the
School of Environmental and Chemical Engineering, Foshan University, Foshan reported catalysts still face a challenge for industrial application
a
5
28000, China. E-mail: junjunshi@fosu.edu.cn
due to the complex catalyst preparation procedures or harsh
reaction conditions. And little attention was focused on the
synergistic effect among acid and base site on a single catalyst.
Zirconium materials possesses important properties: acidity
b
Chongqing Engineering Research Center for Processing, Storage and Transportation of
Characterized Agro-Products, College of Environment and Resources, Chongqing
Technology and Business University, Chongqing 400067, China. E-mail: lok@ctbu.
edu.cn
24
c
and basicity as well as reducing and oxidizing abilities. Zr-
Chongqing Key Laboratory of Catalysis & Environmental New Materials, Engineering
25
26
Research Center for Waste Oil Recovery Technology and Equipment of Ministry of based catalysts, such as ZrO
2
,
Zr-containing zeolites, and
Education, Chongqing Technology and Business University, Chongqing 400067, China Zr(OH)
(ref. 27) were used for the conversion of biomass. In
4
d
State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East
this study, a one-pot process with Zr-based catalysts possessing
China), Qingdao 266580, China
©
2021 The Author(s). Published by the Royal Society of Chemistry
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ꢀ
ꢀ
ꢀ
ꢁ1
both Lewis acid and base site for converting DHA to EL under recorded from 40 C to 850 C with a heating rate of 10 C min
ꢁ1
mild conditions was established (Scheme 1). Type of Zr-based under a 20 mL min air.
catalysts and the impact of various parameters such as cata-
lyst dosage, alcohol choice, reaction temperature and time were 2.3 DHA conversion to EL
also evaluated. In the process proposed here, a remarkable
The DHA conversion to EL was performed in a 30 mL Teon-
synergistic effect exhibited among Lewis acid and base sites on
Zr-based catalyst, giving 100% DHA conversion and 85.3% EL
yield. Furthermore, the Zr-based catalyst showed high thermo-
chemical stability and acceptable recyclability.
lined stainless-steel autoclave. In
a typical experiment,
1.0 mmol DHA, 0.10 g Zr-based catalyst and 10 mL ethanol were
loaded into the reactor and exchanged with N for three times
2
and then maintained with a pressure of 1.0 MPa. Subsequently,
ꢀ
the reactor was placed into an oil-bath maintained at 140 C for
4
.0 h. Aer that, the reactor was cooled down to room temper-
2
. Materials and methods
ature and the catalyst was recovered by centrifugation and
washed with 2 mL ethanol for three times. The recovered cata-
lyst was dried at 60 C for 6.0 h and used for circulation
2.1 Materials
ꢀ
Zr-based catalysts were obtained from Aladdin (Shanghai,
China). Naphthalene, DHA, ML, EL, propyl lactate (PL), and
butyl lactate (BL) were supplied from TCI Development Co. Ltd
experiments.
Qualitative analysis of products was carried out on gas
chromatography-mass spectrometer apparatus (Shimadzu,
GCMS-QP2020) with SH-Rxi-5Sil MS column (30 m, 0.25 mm ꢂ
(Shanghai, China). Other chemical agents were purchased by
Kelong Chemical Factory Co. Ltd (Chengdu, China). Zr(CO3)2
was prepared in laboratory by heating basic zirconium
carbonate at a temperature of 400 C for 4.0 h under static air.
0
.25 mm). The conversion of DHA was carried out on a high-
ꢀ
performance liquid chromatography instrument (Agilent 1200
HPLC) equipped with a refractive index detector (RID) and an
HPX-87H column (300 mm ꢂ 7.8 mm, 5 mm) using the standard
curve method. And the products were conducted on a Shimadzu
GC-2010 Plus equipped with a ame ionization detector (FID)
and RTX®-5 column (30 m, 0.25 mm ꢂ 0.25 mm) based on the
internal standard method (naphthalene as the internal stan-
dard). DHA conversion (CDHA) and EL yield (YEL) were expressed
as following the eqn (1) and (2):
2.2 Material characterization
The microstructure of materials was investigated by scanning
electron microscopy (Bruker, Multimode 8, Germany) at an
accelerating voltage of 5.0 kV. Fourier Transform Infrared
Spectroscopy (FT-IR) of samples were analyzed by IRPrestige-21
spectrometer (Shimadzu, Japan) using KBr pellets in the range
ꢁ
1
ꢀ
ꢁ
from 400 to 4000 cm . X-ray diffraction (XRD) patterns were
undertaken on a LabX XRD 6100 diffractometer (Shimadzu,
M
F2
F1
C
DHAðmol%Þ ¼ 1 ꢁ
ꢂ 100%
(1)
(2)
M
˚
ꢀ
Japan) (Cu Ka-radiation, l ¼ 1.5406 A, 40 kV, 40 mA, 2q ¼ 5–90 )
ꢀ
ꢁ1
with a scan rate of 3 min . NH and CO temperature pro-
MEL
ELðmol%Þ ¼ MF1 ꢂ 100%
3
2
Y
grammed desorption (NH -TPD and CO -TPD) were recorded by
3
2
a BELCAT II instrument with a thermal conductivity detector
where MF1 and MF2 stand for the mole of DHA before and aer
reaction, respectively, and MEL stands for the mole of EL
quantied by GC.
ꢀ
(
2
BEL Japan). Each material was heated at 120 C for 3.0 h under
ꢁ1
0 mL min . He for removing of water and any other physically
ꢀ
absorbed gas and then cooled to 100 C. Subsequently, 20
mL min 5% NH
ꢁ
1
3 2
or CO was absorbed for 1.0 h, following by
ꢁ1
3. Results and discussion
purging with 20 mL min . He to remove the physically absor-
bed NH or CO for other 1.0 h. The resulting data was obtained 3.1 Catalyst characterization
3
2
ꢀ
ꢀ
ꢀ
ꢁ1
from 100 C to 470 C at a rate of 10 C min . N adsorption–
2
XRD pattern of basic zirconium carbonate indicates that this
material is amorphous in nature with no obvious diffraction
peaks. Small size particles without uniform structure could be
observed in SEM images, which is well accorded with the XRD
pattern (Fig. 1a). Furthermore, N2 physisorption prole
demonstrates that basic zirconium carbonate possesses
a typical type IV isotherm with a H3-type hysteresis loop and
a broad distribution of pore sizes (Fig. 1b). In the solid FT-IR
desorption isotherms were obtained by a Micromeritics' ASAP
ꢀ
2
020 HD88 Analyzer at ꢁ196.15 C before the materials were
ꢀ
dehydrated at 100 C for 24 h under vacuum. Thermo-
gravimetric analysis (TGA) was measured by a STA 449 F3
instrument (Netzsch, Germany). The materials were heated at
ꢀ
8
0 C for 6.0 h under vacuum prior to analysis. The curves were
ꢁ1
spectrogram (Fig. 1c), the peaks between 3220 and 3680 cm
can be assigned to the –OH stretching on the catalyst surface or
2
8
ꢁ1
absorbed trace water. Absorption at 2350 cm is asymmetric
ꢁ
1
stretching of CO
2
. The two signals at 1515 and 1367 cm and
the single peak located at 1081 cm are attributed to the
asymmetric stretching and symmetric stretching of CO
respectively. The peak detected at 836 cm is considered as
ꢁ1
2
ꢁ
,
3
29
ꢁ1
3
0
Scheme 1 Conversion of DHA to EL by Zr-based catalysts.
the stretching of Zr–O.
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respectively (Table 1, entries 2, 5 and 6), demonstrating that
12,31
single Lewis acid or base site shows lower active.
selectivity for EL production slightly decreased from 85.3% to
8.2% and 80.3% in the presence of piperidine and benzoic
Besides,
7
acid. These results suggested that the synergistic effect among
acid and base sites of catalyst plays a key role in the formation of
EL.
To further understand the effect of active sites on the
complex structure of basic zirconium carbonate (Zr–OH, Zr]O
and Zr–CO ), a series of comparing catalysts (NaOH for –OH,
3
Fig. 1 Basic zirconium carbonate characterization: (a) SEM image and
Zr(OH)4 for Zr–OH, ZrO2 for Zr]O, Na CO for –CO , and
2
3
3
XRD pattern, (b) N
2
physisorption profile, (c) FT-IR profile, (d) TG-DTG
-TPD profile.
Zr(CO ) for Zr–CO ) were employed. Only 40.3% EL was ob-
3
2
3
curve, (e) NH -TPD profile and (f) CO
3
2
tained with NaOH (Table 1, entry 7), lower than that from
Zr(OH) catalyst of 57.6% (Table 1, entry 3), which can be
attributed to the formation of humins from glyceraldehyde via
4
Additionally, the thermal behavior of Zr-based catalyst
Fig. 1d) was also analyzed by TG-DTG. It shows that basic
32
the isomerization of DHA in the presence of strong base.
Meanwhile, as shown in Table 1, it is also noticed that either
Zr(CO3)2 or Na CO exhibited lower catalytic activity on EL
(
zirconium carbonate has three degradation peaks. Between 40
ꢀ
2
3
and 227 C, the weight loss (8.5 wt%) can be assigned to the
production but higher EAPA yield (Table 1, entries 8 and 9). For
example, EL yield obtained from Zr(CO ) was 12.7%, which was
removal of absorbed and structural water. The second one (227–
ꢀ
3 2
4
63 C) exhibits a 7.4 wt% weight loss, which can be explained
much lower than Zr(OH)
4
of 57.6%. However, EAPA yield from
(only
by the dehydration of hydroxyl groups upon the basic zirconium
Zr(CO (43.1%) was much higher than that from Zr(OH)
3
)
2
4
2
9
ꢀ
carbonate. Further increased to 550 C, 5.2 wt% weight loss
2
ꢁ
28
0.8%). It is indicated that Zr–OH was the active site for EL in our
can be observed due to the decomposition of CO
3
. The above
process, which is well consistent with the previous study that
results clearly suggest that the catalyst has high thermal
stability over a broad temperature, which can be applied in
33
M–OH is responsible for the conversion EAPA to EL. In addi-
tion, the EL yield decreased from 85.3% to 68.3% under 1.0 MPa
biomass renery. NH
carbonate can be classied as weak and moderate acid sites
Fig. 1e). Meanwhile, we can also observe the coexistence of
3
-TPD curve shows basic zirconium
O (Table 1, entries 2 and 10), which may be attributed to the
2
oxidation of carbonyl (aldehyde) group by superoxide radical
(
34
anions according to Lin's work. Furthermore, 90.8% DHA
conversion and 78.9% EL yield could still be achieved aer three
runs (Table 1, entry 11), demonstrating that the basic zirconium
carbonate catalyst has good recyclability.
weak, moderate, and strong base sites based on the desorption
temperature, respectively (Fig. 1f), demonstrating that surface
of basic zirconium carbonate exhibits both acid and base
characteristics, which is important to establish the impressive
activity and selectivity of EL in this catalyst system.
3.2 Catalytic performance of Zr-based materials
3.3 The effect of various reaction parameters
The catalytic activities of various Zr-based catalysts were inves- The effect of reaction temperature and time on process effi-
ꢀ
tigated for converting DHA into EL at 140 C for 4.0 h. The result ciency of EL production is presented in Fig. 2a and b, which
shows that the conversion of DHA to EL is insignicant without shows that this process is highly temperature-dependent. For
any catalyst (only 5.1%, Table 1, entry 1). However, when various example, EL yield remarkably increased from 45.1% to 82.9%
Zr-based catalysts were employed, a remarkable increase of accompanying with DHA conversion improved from 73.3% to
ꢀ
conversion and EL yield could be observed. For example, basic 97.8% when the temperature was rose from 120 to 150 C at
zirconium carbonate showed the best performance, giving 1.0 h. Both the DHA conversion and EL yield could also be
1
00% DHA conversion with 85.3% EL yield (Table 1, entry 2). enhanced by the extending reaction time. For example, 100%
Whereas, the yield of EL decreased to 57.6% with Zr(OH) (Table DHA conversion and 83.1% EL yield can be obtained by
, entry 3). It is worth noting that clear difference was observed extending the reaction time to 7.0 h. Furthermore, the yield of
4
1
in product distribution using ZrO as the catalyst (Table 1, entry DEPAP, the only by-product detected, was decreased from
2
ꢀ
4
), where the major product was ethyl acetal of pyruvic aldehyde 20.2% to 4.5% when the temperature rose from 120 to 150 C.
(EAPA, 38.9% yield).
This indicates that higher temperature facilitates the conver-
In general, piperidine and benzoic acid, as the deactivators sion of EAPA to EL but lower temperature favors conversion
of acid/base sites upon the surface of catalyst, were employed to EAPA to DEAPA, which is well accordance with the previously
35,36
explore the role of acid and base sites during the reaction. As reported works.
Besides, the DEAPA yield decreased with the
shown in Table 1, it can be seen that a notable decrease of EL increase of reaction time and temperature, which could be
yield was achieved in the presence of either probe molecules. explained by the conversion of DEAPA to EAPA and further to
17
ꢀ
For example, DHA conversion decreased from 100% to 70.4% EL. For example, under 120 C and 5.0 h, 100% DHA conver-
and 63.2%, accompanying with EL yield decreasing from 85.3% sion and 75.9% EL yield were obtained, and the EL yield
to 55.1% and 50.7% with 1.0 mmol piperidine or benzoic acid, increased to 83.1% with extending reaction time to 7.0 h. Thus,
©
2021 The Author(s). Published by the Royal Society of Chemistry
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a
Table 1 Catalytic activity tests of Zr-based catalysts
b
Yield (%)
Entry
Catalyst
Blank
Conversion (%)
Selectivity (%)
1
2
3
4
5.1 ꢃ 0.9
100
100
76.3 ꢃ 1.7
70.4 ꢃ 1.4
63.2 ꢃ 1.3
100
81.7 ꢃ 1.9
37.1 ꢃ 1.8
100
—c
—
—
—
—
(ZrO)
Zr(OH)
ZrO
2
CO
3
(OH)
2
85.3 ꢃ 1.2
57.6 ꢃ 1.8
8.1 ꢃ 0.9
55.1 ꢃ 1.8
50.7 ꢃ 0.7
40.3 ꢃ 1.7
10.4 ꢃ 0.7
2.7 ꢃ 1.1
68.3 ꢃ 2.1
78.9 ꢃ 2.0
1.3 ꢃ 1.1
2.8 ꢃ 0.5
3.4 ꢃ 0.8
3.7 ꢃ 1.1
4.3 ꢃ 1.5
—
4.9 ꢃ 1.1
3.1 ꢃ 1.0
1.8 ꢃ 0.7
3.3 ꢃ 1.1
85.3 ꢃ 1.4
57.6 ꢃ 1.3
10.6 ꢃ 1.0
78.2 ꢃ 1.4
80.3 ꢃ 0.9
40.3 ꢃ 1.6
12.7 ꢃ 1.3
7.3 ꢃ 1.2
68.3 ꢃ 1.8
86.8 ꢃ 1.4
4
0.8 ꢃ 0.3
2
38.9 ꢃ 1.3
d
5
(ZrO)
(ZrO)
2
CO
CO
3
(OH)
(OH)
2
—
e
6
2
3
2
—
—
7
8
NaOH
Zr(CO
Na CO
3
)
2
43.1 ꢃ 2.1
10.5 ꢃ 1.3
—
9
1
1
2
3
f
0
1
(ZrO)
(ZrO)
2
CO
CO
3
(OH)
(OH)
2
g
2
3
2
90.8 ꢃ 1.7
—
a
ꢀ
b
Reaction conditions: 1.0 mmol DHA, 0.10 g catalyst, 10 mL ethanol, 140 C, 4.0 h, 1.0 MPa N
2
.
The products listed as following: ethyl lactate (EL),
c
d
e
ethyl acetal of pyruvic aldehyde (EAPA), diethyl acetal of pyruvic aldehyde (DEAPA). (—): not detected. Adding with 1.0 mmol piperidine. Adding
with 1.0 mmol benzoic acid. 1.0 MPa O . The 3 cycle of basic zirconium carbonate.
2
f
g
th
Fig. 2d and e, the EL yield remained approximately constants
aer removing the catalyst for 1.0 h with both cold (room
ꢀ
temperature) and hot (60 C) ltration. Meanwhile, no zirco-
nium ions were detected in the above ltrates by ICP-AES
analysis. These ndings demonstrate that the active sites on
the surface of the catalyst are stable during the process.
Inspired by the outstanding catalytic performance of basic
zirconium carbonate for converting DHA to EL in ethanol, the
inuence of alcohol choice was further investigated. In Fig. 2f,
the process efficiency changed markedly in different alcohols.
With methanol, a slight decrease of ML yield (80.1%) was shown
Fig. 2 Effects of various parameters on transformation of DHA to EL
over basic zirconium carbonate: (a and b) reaction temperature and compared to that with ethanol (85.3%), which can be attributed
time, 1.0 mmol DHA, 0.10 g basic zirconium carbonate, 10 mL ethanol;
to the lowest steric hindrance, resulting in the formation of
ꢀ
(
c) dosage, 1.0 mmol DHA, 10 mL ethanol, 140 C, 4.0 h; (d and e)
14
1,1,2,2-tetramethoxypropane (8.9%). Further extending the
leaching tests, 1.0 mmol DHA, 0.10 g basic zirconium carbonate, 10 mL
ꢀ
carbon chain of n-alcohol, a declined trend of the correspond-
ethanol, 140 C; (f) alcohol choice, 1.0 mmol DHA, 0.10 g basic
zirconium carbonate, 10 mL alcohol, 140 C, 4.0 h, others stands for ing alkyl lactates yield was observed, which may be explained by
ꢀ
the resulting dialkylacetal of pyruvic aldehyde except in methanol the increasing effect of steric hindrance. For example, only
media where 1,1,2,2-tetramethoxypropane is the only detected by-
product.
7
5.4% BL yield was generated from n-butanol. This effect of
steric hindrance was more obvious for i-propanol, where only
60.2% isopropyl lactate yield was achieved.
ꢀ
from the above discussion, 140 C and 4.0 h are required to
achieve excellent process efficiency.
3.4 Reaction pathway of the DHA conversion
37–43
Fig. 2c shows that catalyst dosage plays a critical role in the Based on the above discussion and previous reports,
conversion of DHA to EL. A negligible process efficiency was a probable reaction pathway for transformation of DHA to EL is
observed without any catalyst (Table 1, entry 1). However, it was
signicantly improved aer adding 0.05 g basic zirconium
carbonate, giving 85.3% DHA conversion and 55.5% EL yield
(Fig. 2c). The peak value of EL yield (85.3%) was achieved at
0.10 g catalyst. However, a decrease trend of EL yield was ob-
tained when catalyst loading increased to 0.175 g. Hence, 0.10 g
ꢀ
of the catalyst would be the optimum amount at 140 C for
4
.0 h.
Leaching tests were also conducted to investigate the
chemical stability under optimal conditions. As exhibited in
Scheme 2 Reaction pathway for conversion of DHA to EL over basic
zirconium carbonate.
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proposed (Scheme 2). Firstly, the DHA is isomerized to glycer-
References
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aldehyde (Step 1). The dehydration and rearrangement reac-
tion catalyzed by both Brønsted and Lewis acids undergoes,
giving an important intermediate compound-pyruvic aldehyde
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41–43
5).
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14
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14
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ꢀ
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Conflicts of interest
There are no conicts to declare.
20 W. Oberhauser, C. Evangelisti, S. Caporali, V. Dal Santo,
F. Bossola and F. Vizza, J. Catal., 2017, 350, 133.
21 X. Lyu, L. Wang, X. Chen, L. Xu, J. Wang, S. Deng and X. Lu,
Ind. Eng. Chem. Res., 2019, 58, 3659.
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22 X. Lyu, M. Xu, X. Chen, L. Xu, J. Wang, S. Deng and X. Lu, Ind.
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The authors gratefully acknowledge the nancial support of the
National Natural Science Foundation of China (Grant No. 23 P. M ¨a ki-Arvela, I. L. Simakova, T. Salmi and D. Y. Murzin,
1808021 and 21808032), the Natural Science Foundation of
Chem. Rev., 2013, 114, 1909.
Guangdong Province (Grant No. 2018A030310351), the Science 24 G. Yang, Y. Ke, H. Ren, C. Liu, R. Yang and W. Dong, Chem.
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Eng. J., 2016, 283, 759.
Wattanapaphawong,
A. Yamaguchi, RSC Adv., 2017, 7, 18561.
2
Education Commission (Grant No. KJQN201800828, KJZD- 25 P.
M201900802 and KJZD-K201800801) and the Startup Founda-
tion of Chongqing Technology and Business University (Grant
No. 950318060).
P.
Reubroycharoen
and
©
2021 The Author(s). Published by the Royal Society of Chemistry
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