Efficient conversion of cellulose to lactic acid over yttrium modified siliceous Beta zeolites

Article abstract of DOI:10.1016/j.apcata.2021.118133

The selective one-pot synthesis of lactic acid (LA) from cellulose, and further the raw biomass, on heterogeneous catalysts is the key point for the development of biorefinery technology. Herein, we reported an yttrium (Y) modified siliceous Beta zeolites catalyst via two-step post-synthesis for highly efficient conversion of cellulose to LA. Under condition of 220 °C and 2 MPa N₂, the cellulose could be transformed to LA with a yield of 49.2 % within 30 min, and the substrate can be extended to various raw biomass. It was demonstrated that the dealumination and modification of Y can efficiently modulate the acidity on the surface of zeolite. The dehydration products HMF and other derivatives were suppressed, and the yield of LA was correlated in line with the acid amount, which were attributed to the increased Lewis acidity originated by Y incorporation. These results contribute to the development of the green and efficient synthesis of bio-chemicals.

Full text of DOI:10.1016/j.apcata.2021.118133

Applied Catalysis A, General 619 (2021) 118133
Contents lists available at ScienceDirect
Applied Catalysis A, General
journal homepage: www.elsevier.com/locate/apcata
Efficient conversion of cellulose to lactic acid over yttrium modified
siliceous Beta zeolites
a
,
b
,
e
a
,
b
a
,
b
c
a,
b
d
Juan Ye
, Chenyu Chen , Ying Zheng , Dan Zhou , Yunzhen Liu , Denglong Chen ,
e
a,
b,
e,
Liufang Ni , Gang Xu
*, Fanan Wang **
a
College of Chemistry and Material Science, Fujian Normal University, Fuzhou, 350007, China
b
c
Fujian Provincial Key Laboratory of Polymer Materials, College of Chemistry and Materials Science, Fujian Normal University, Fuzhou, 350007, China
Department of Chemical Machinery, Faculty of Chemical Engineering and Biological Science, Dalian University of Technology, Dalian, 116024, China
Quangang Petrochemical Research Institute of Fujian Normal University, Quanzhou, 362801, China
d
e
Fujian Eco-materials Engineering Research Center, Fujian University of Technology, Fuzhou, 350118, China
A R T I C L E I N F O
A B S T R A C T
Keywords:
The selective one-pot synthesis of lactic acid (LA) from cellulose, and further the raw biomass, on heterogeneous
catalysts is the key point for the development of biorefinery technology. Herein, we reported an yttrium (Y)
Lactic acid
Cellulose
modified siliceous Beta zeolites catalyst via two-step post-synthesis for highly efficient conversion of cellulose to
Yttrium-Beta
Lignocellulosic biomass
Lewis acid
◦
LA. Under condition of 220 C and 2 MPa N
2
, the cellulose could be transformed to LA with a yield of 49.2 %
within 30 min, and the substrate can be extended to various raw biomass. It was demonstrated that the deal-
umination and modification of Y can efficiently modulate the acidity on the surface of zeolite. The dehydration
products HMF and other derivatives were suppressed, and the yield of LA was correlated in line with the acid
amount, which were attributed to the increased Lewis acidity originated by Y incorporation. These results
contribute to the development of the green and efficient synthesis of bio-chemicals.
1
. Introduction
With the wide availability and huge scale of annual yield, biomass,
[15–18]. Among them, the redro-aldol of fructose is considered to be the
rate-determining step [16,19]. Furthermore, the selectivity for LA suf-
fered from multiple side-reactions with by-products such as HMF, LeA
and solid humins. Hence, specific C-C cleavage and C-O activation are
essential for the efficient one-pot synthesis of LA from cellulose [17],
which requires well-designed catalysis systems. Specifically, the first
hydrolysis of cellulose can be driven by Brønsted acidity; while the
following steps of isomerization and retro-aldol reaction are favored via
catalysts with Lewis acidity and/or basicity [12]. Catalysts with acidic
sites, especially various types of solid Lewis acids, have been extensively
studied in recent years. For instance, Marianou et al. [15] investigated
various oxides, heteropolyacids, and oxides supported heteropolyacids,
the only sustainable and green carbon source, possesses an immense
potential to complement fossil-derived carbons [1,2]. The clean and
efficient conversion of biomass to energy and chemicals, generally
termed as “biorefinery technology”, has become a crucial strategy of
development all over the world [3,4]. As the most abundant component
of biomass, cellulose can be hydrolyzed to yield glucose, which can be
subsequently converted into a variety of platform chemicals such as
fructose [5], sorbitol [6,7], 5-hydromethylfurfural (HMF) [8,9], levu-
linic acid (LeA) [10], glycol [11], LA [12,13], etc. Among these, LA has a
wide range of applications in food industry, pharmaceuticals, biode-
gradable plastics, and green solvents, with a global market valued at
approximately $2.9 billion in 2018 and assessed around $8 to 10 billion
by 2025 [14,15].
and found that TSA/SiO
2
-Al
2
O
3
, with the highest Lewis to Brønsted
acidity ratio, led to the highest LA selectivity (38.4 %) and yield (23.5
%), at 61.2 % cellulose conversion. Other solid catalysts with pro-
5 3 2
nounced Lewis acidity, such as Zr-SBA-15 [20], NbF -AlF [21], ZrO
The hydrothermal conversion of cellulose into LA involves consec-
utive steps of cellulose hydrolysis to glucose, glucose isomerization to
fructose and fructose transformation into LA via retro-aldol pathway
[22], Er/K10(S)-3 [23], Al (WO [24], are also employed as active
2
4 3
)
catalysts to facilitate the sluggish steps.
Among all the chosen materials, Beta zeolites are one of the most
*
Corresponding author at: College of Chemistry and Material Science, Fujian Normal University, Fuzhou, 350007, China.
** Corresponding author at: Fujian Eco-materials Engineering Research Center, Fujian University of Technology, Fuzhou, 350118, China.
E-mail addresses: xugang@fjnu.edu.cn (G. Xu), fanan_wang@fjut.edu.cn (F. Wang).
https://doi.org/10.1016/j.apcata.2021.118133
Received 9 January 2021; Received in revised form 19 March 2021; Accepted 1 April 2021
Available online 15 April 2021
0
926-860X/© 2021 Elsevier B.V. All rights reserved.

J. Ye et al.
Applied Catalysis A, General 619 (2021) 118133
studied and enjoy multiple inherent merits [25–30]. The
three-dimensional interconnected channel structures render them large
surface area and confinement effect for loading of active catalytic
components and the complete reaction of intermediates. They also have
abundant acidity sites on their surface, making them promising catalyst
and/or multifunctional supports. Furthermore, their surface chemical
properties can be adjusted by acid treatment and ion exchange with
metal ions. As an example, Holm et al. [16] reported that, the H-Al-Beta
zeolite with Brønsted acidity catalyzed the dehydration of the sugars,
leading to HMF and other derivatives. While after modified with Ti, Sn,
or Zr, the zeolites featured Lewis acidity and were active for the con-
version of sugars to LA derivatives, and Sn-Beta zeolite with the stron-
gest Lewis acidic sites exhibited the most selectivity. Besides, with
hemicellulose and cellulose in its components, the raw lignocellulosic
biomass, such as corn stover, can be utilized as feedstock for the pro-
duction of LA [31]. A transition metal and Sn incorporated Beta zeolite
was reported to directly convert raw biomass into lactic acid with a yield
of 33.4 %. The strong Lewis acidity originated from transition metal and
the relatively weak Lewis acidity from Sn were rationalized to serve as
multifunctional active sites [32]. However, the application of Beta ze-
olites in the one-pot conversion of cellulose and the raw biomass to LA
still suffered from low yield.
2.2. Catalyst preparation
Y-Beta zeolite catalysts were prepared through a two-step procedure,
consisting of the dealumination of the Al-Beta zeolite and then intro-
duction of Y species via solid-state ion-exchange. In a typical process, the
commercial Al-Beta zeolite was stirred in a 13 mol/L nitric acid aqueous
◦
solution at 100 C overnight to obtain dealuminated Beta (deAl-Beta).
The deAl-Beta was filtered, washed thoroughly with deionized water,
◦
and dried at 110 C overnight. Afterward, the dried deAl-Beta was
ground with Y(NO
3
)
3
∙6H
2
O in agate mortar for 0.5 h; then the mixture
◦
◦
was dried at 110 C overnight and calcined at 550 C for 6 h to obtain Y-
Beta. The zeolite samples after calcination were directly used as the
catalysts without any reduction treatment. The final product was labeled
by x%-Y-Beta, where x indicated the designated weight loading of metal
in the sample.
2.3. Characterization techniques
Powder X-ray diffraction (XRD) patterns were acquired with an
XPert Pro MRD diffractometer equipped with a Cu-K
α
source (40 kV,
◦
40 mA). Data points were acquired by step scanning with a rate of 5 /
◦
◦
min from 2θ = 5 ꢀ 50 . Nitrogen adsorption-desorption measurements
◦
The introduction of Y species can lead to the formation of Lewis
acidity in the catalysis system, and have been applied in plenty of acid-
catalyzed organic transformations [33,34]. Yan et al. [35] developed a Y
modified siliceous Beta zeolite catalyst via dealumination of the parent
Beta zeolite and then introduction of Y species via wet impregnation.
They demonstrated that the surface Brønsted acidic sites were elimi-
nated by the dealumination, and the surface Lewis acidic sites increased
in line with the incorporation of Y raised from 2% to 10 %, which
accounted for the high efficiency of one-pot conversion of acetic acid to
isobutene. In the field of biomass conversion, trivalent Y species was
reported as a homogeneous catalyst for the direct synthesis of LA from
were performed at ꢀ 196 C with a Micromeritics ASAP-2460 surface
area analyzer. Prior to the measurements, the samples were degassed at
◦
◦
110 C and 250 C for 1.5 h and 5 h, respectively. The specific surface
areas were calculated with BET equation. The micropore volume was
determined by t-plot model, and the micropore size distribution was
obtained by DFT method. FTIR spectra of the silanol vibration region
and pyridine adsorption were obtained using a Thermo Scientific Nicolet
6700 spectrometer equipped with a liquid nitrogen-cooled MCT detec-
tor. Samples for IR spectroscopy were prepared by pressing catalyst into
a 20 mm diameter pellet and placing it into a custom-built transmission
cell fitted with CaF windows. All pellets were pretreated in dry air at
2
+
3+
◦
the actual biomass. The [Y(OH)
2
2
(H O)
2
]
species derived from Y
450 C for 1 h to remove any water in the material; spectra were ac-
◦
hydrolysis was responsible for the the simultaneous conversion of
hemicellulose and cellulose components in rice straw to obtain a LA
yield of 66.3 % [36]. While to the best of our knowledge, there has been
few reports of supported Y catalysts on the conversion of cellulose or raw
lignocellulose to LA yet.
quired at 150 C. For pyridine adsorption, 2
μ
L of pyridine was injected
◦
for each experiment and desorbed at 150 C, then the FTIR spectrum of
pyridine was obtained. The total acid capacity was determined by
ammonia temperature programmed desorption (NH -TPD) using the
3
Micromeritics Autochem 2910 unit. Scanning electron microscopy
Based on the above discussion, we herein reported a Beta zeolite
supported Y (Y-Beta) catalyst for efficient conversion of cellulose, and
further the raw biomass to LA. The catalysts were synthesized through
the modified method reported by Yan et al. [35], with the incorporation
of Y via a solid-state ion-exchange. The prepared catalysts were thor-
oughly characterized with respect to their crystal structure,
morphology, porosity and acidity. The product yield was correlated with
the acidity. The as-prepared Y-Beta can efficiently transform cellulose to
LA, and the substrates can be extended to several raw biomass. Attempts
have been made to optimize reaction conditions and investigate the
reaction mechanism.
(SEM) was conducted on a SU8220 electron microscope at an acceler-
ation voltage of 5.0 kV. Transmission electron microscopes (TEM) was
carried out on a JEM-2100 F electron microscope equipped with a field
emission gun operating at an accelerating voltage of 200 kV. The sam-
ples were prepared by dropping ethanol dispersion of catalysts onto
carbon-coated copper TEM grids (Ted Pella, Redding, CA) using pipettes
and dried under ambient condition. X-ray photoelectron spectroscopic
(XPS) analyses were performed on a Kratos Axis Ultra spectrometer
(Kratos Analytical, UK) equipped with a monochromatized aluminum X-
ray source. Inductively coupled plasma (ICP) experiments were per-
formed on a Thermo IRIS Intrepid II spectrum apparatus to determine
the actual Y contents. The carbon content of cellulose and lignocellulose
was measured by the Thermo Flash 2000 CHNS/O Elemental Analyzer.
2
. Experimental
2
.1. Materials
2.4. Catalytic experiments and product analysis
Microcrystalline cellulose (average particle size 50
μ
m), D-fructose
The catalytic conversion was conducted in a stainless steel autoclave
(HuoTong, 50 mL) with a mechanical stirrer. Generally, a mixture of
cellulose, the solid acid catalyst, and ultra-pure water were loaded into
the autoclave. After the autoclave was sealed, the atmosphere in the
(
99 %), D-(+)-glucose (99 %), D-(+)-xylose (99 %), LeA (95 %), LA (90
), formic acid (88 %), acetol (90 %), HMF (≥99 %), Y(NO ∙6H
99.5 %) and Y (99.99 %) were purchased from Aladdin. A com-
%
3
)
3
2
O
(
2 3
O
mercial beta zeolite (Si/Al ratio of 25) was purchased from Catalyst
Plant of Nankai University (Tianjin, China). Bamboo, pine and rice husk
were obtained from Fujian province, China. Before reaction, they were
dried at 393 K, milled, and screened into powder with the size of <60
meshes. Other reagents were all analytical grade and used without
further purification.
reactor was replaced three times with N
2 2
and then 2 MPa N was
charged. The reactor was heated to the desired temperature with a
◦
ꢀ 1
heating rate of ~5 C min and kept for a designed time. After the re-
action, the aqueous solution was separated from the solid catalyst by
filtration and cooled in an ice bath. The solid catalyst was collected and
◦
dried at 120 C overnight.
2

J. Ye et al.
Applied Catalysis A, General 619 (2021) 118133
2 3 2
Fig. 1. a) XRD patterns of Y O , deAl-Beta, and different Y-Beta catalysts; b) TEM images of Y-Beta with corresponding element mapping. c) N adsorption-
desorption isotherms and d) corresponding pore size distribution curves for various catalysts.
Products analysis were analysed by high performance liquid chro-
matography (HPLC) in a Shimadzu LC-10 chromatograph equipped with
a refractive index detector (RID-10A, Shimadzu) and a Xtimate Sugar-H
The concentrations of all components were determined by comparison
to the standard calibration curves. The mass of unconverted cellulose
was determined by deducting the mass of the initial catalyst from the
total mass of the solid residue after reaction, ignoring the wastage of the
catalyst. The cellulose conversion can be calculated as followed:
Cellulose conversion (%):
ion exclusion column (300 × 7.8 mm, 8
SO as the mobile phase at a flow rate of 0.6 mL/min. The column
temperature was 60 C and the detector temperature was set to 40 C.
μ
m particle, YueXu), using 5 mM
H
2
4
◦
◦
2 3
Fig. 2. a) FTIR spectra in the hydroxyl stretching vibration region of H-Beta, deAl-Beta and 10 % Y-Beta. b) Y 3d XPS of 10 % Y-Beta and reference Y O3. c) NH -TPD
◦
profiles of the catalysts. d) Py-IR spectra of the catalysts at 150 C.
3

J. Ye et al.
Applied Catalysis A, General 619 (2021) 118133
(
m ass of the solid residue - m ass of the initial catalyst)
Conversion(%) = 1 ꢀ
× 100%
(1)
m ass of initial cellulose
Yield of product i (C %):
m ol of carbon in target product
of all samples demonstrated the inherent microporous structure of the
zeolite. It also indicated the presence of mesopores, which may be
attributed to the interparticle voids of the random stack of the nano-
crystals and/or the collapse inside the zeolite crystals after the deal-
umination (Fig. 1c-d). As listed in Table S1, after modification with the Y
species, the micropore surface area of the catalysts decreased from
Yield(%) =
× 100%
(2)
m ol of carbon in initial cellulose
For the raw biomass, only cellulose (composed of C6 units) and
hemicellulose (composed of C5 units) can be converted into lactic acid,
whereas lignin cannot produce lactic acid. Therefore, as commonly
applied in literatures, the yield of lactic acid here was calculated based
on C6 and C5 monomeric units contained in the raw biomass using the
following equation [18,36,37]:
2
ꢀ 1 ꢀ 1
2
4
29 m g to 295 m g , and the micropore pore volume decreased
3
ꢀ 1
3
ꢀ 1
from 0.17 cm g to 0.12 cm g .
The FTIR spectra spectrum in the hydroxyl stretching region were
given in Fig. 2a). For parent H-Beta, there were two characteristic bands
ꢀ 1
ꢀ 1
centered at 3735 cm and 3600 cm , which were assigned to the
m oles of obtained lactic acid
Yield(%) =
× 100%
(3)
m oles of C5 units in the feedstock + 2 × m oles of C6 units in feedstock
3
. Results and discussion
isolated external Si
–
OH groups and the bridging hydroxyls (Si-OH-Al),
respectively27. After the dealumination, the band related to Al species
(Si-OH-Al) disappeared, meanwhile the band due to the isolated internal
Y-Beta catalysts were prepared through a two-step procedure, con-
ꢀ 1
sisting of the dealumination of the H-Beta (deAl-Beta) and then intro-
duction of Y species via solid-state ion-exchange. As can be seen from the
XRD results (Fig. 1a), samples after dealumination and Y introduction
inherited the crystalline structure of the original H-Beta, with typical
diffraction lines characteristic of the BEA topology [28,38]. However,
compared to the parent zeolite, the intensities of the reflections
decreased with the increase of Y content, indicating the gradual loss of
Si OH groups intensified, and a new band at around 3540 cm
–
attributed to hydrogen-bonded silanol groups occurred. With the
introduction of Y species, the intensities of the bands related to the
–
Si OH decreased obviously, indicating the incorporation of Y with
silanol groups [35].The XPS analyses were further carried out. As can be
seen from Fig. 2b), in the Y 3d XPS spectra of the Y-Beta, signals of
binding energy at 160.2 and 158.5 eV were corresponded to Y 3d5/2 and
3d3/2, respectively, which were obviously higher than those for bulk
the crystallinity. No obvious diffraction peaks from Y
2 3
O crystallites
(
JCPDS: 76-0151) were detected, demonstrating that Y was either
Y
2
O
3
(158.5 and 156.6 eV), demonstrating the formation of the Si-O-Y
bond [35,39,40].
The NH -TPD analyses were conducted to investigate the modifica-
amorphous or highly dispersed within the zeolite matrix. The TEM im-
ages (Fig. S1) and the element mapping (Fig. 1b) of 10 % Y-Beta dis-
played the hierarchical pores of the support, and no obvious
Y-containing aggregates, further confirming the homogeneous distri-
bution of Y species. The SEM images of 10 % Y-Beta (Fig. S2) showed
that the catalyst was composed of closely stacked zeolite nanocrystals
and the particle size of the final catalyst was in range of 50ꢀ 100 nm. The
3
tion of surface acidity. As can be seen from Fig. 2c), the parent H-Beta
◦
showed a large NH
3
desorption peak centered at approximately 200 C
◦
and a broad peak at 300–500 C, corresponding to weak and strong
acidic sites, respectively. After dealumination and introduction of Y, the
3
intensities of the peaks for NH desorbed from both weak and strong
N
2
physisorption isotherms and the corresponding pore size distribution
acidic sites decreased significantly compared to the parent H-Beta,
revealing the disappearance of a large number of acidic sites because of
removal of aluminum atoms from the framework [41]. With the increase
of the Y amount, the peak areas gradually rose up, revealing an increase
on total acid amount, which was specifically listed in Table S2.
To further identify the surface acidity, the pyridine adsorption IR
spectroscopies were taken out. Three main classes of vibrations could be
assigned: i) vibrations related to physiosorbed and/or hydrogen bonded
ꢀ 1
pyridine generated by both Lewis and Brønsed acid sites (1490 cm ); ii)
vibrations arising from coordination of pyridine to Lewis acid centers
ꢀ
1
(
1620ꢀ 1600, 1455ꢀ 1445 cm ); and iii) vibrations related to pyridine
ꢀ 1
protonated by Brønsted acid centers (1637, 1540 cm ) [25,42]. As can
be seen from Fig. 2d), there existed vibrations attributed to both
Brønsted and Lewis acid sites on the surface of parent H-Beta. After
dealumination and introduction of 10 % Y, the characteristic of Brønsted
acid was almost absent and only Lewis acid sites were present. These
findings were consisting with the previous studies that the incorporation
of Y within the zeolite could create Lewis acid sites35. Hence, the
3
increased acid amount from NH -TPD analysis was attributed to the
Lewis acidity originated from Y loading. These results demonstrated the
dealumination and modification of Y could efficiently modulate the
Fig. 3. Catalytic performances of various catalysts. Reaction conditions: cel-
◦
lulose 0.3 g, water 30 mL, catalyst 0.1 g, 220 C, 2 MPa N
2
, 30 min.
4

J. Ye et al.
Applied Catalysis A, General 619 (2021) 118133
Table 1
that cellulose hydrolysis to glucose was catalyzed by Brønsted acid sites.
Afterwards, with the aid of Lewis acidity, glucose may isomerize to
fructose, which subsequently either dehydrates to HMF (Brønsted
acidity) or converts into LA via retro-aldol reactions (Lewis acidity) [15,
The comparison of to LA by different catalyst systems.
Substrate
Catalyst
Temperature
Time
(h)
LA
Year
ref
o
(
C)
yield
(
%)
1
6]. In our case, the cellulose could be depolymerized by the water
glucose
In–Sn-Beta
190
190
220
175
2
53
2020
2019
2019
2019
[43]
[44]
[24]
[15]
autoprotolysis due to the increased ionization constant of hot water
◦
cellulose
cellulose
cellulose
ZrW
24
3
28
(220 C). While for the Y-Beta, the elimination of Brønsted acid sites
Al
TSA/SiO
Al
Y-Beta
2
(WO
4
)
3
46
dramatically suppressed the dehydration of fructose to HMF and the
further decomposition of HMF. The re-formation of sufficient Lewis acid
sites facilitated the isomerization and retro-aldol reactions, leading to
high selectivity of LA.
2
-
24
23.5
O
2 3
cellulose
220
0.5
49.2
This
work
The optimal reaction conditions for the conversion of cellulose to LA
were further investigated. It can be seen from Fig. 4 a and b that the
acidity on the surface of zeolite.
◦
optimal temperature and reaction time were 220 C and 30 min,
To evaluate the catalytic performance of the as-obtained catalysts,
respectively. With further increasing the temperature and reaction time,
the conversion of cellulose and the yield of LA remained almost stable,
confirming the stability and negligible overreaction of the LA. The best
catalyst dosage was determined to be 0.1 g for 0.3 g cellulose amount
the hydrothermal conversion of cellulose to LA was conducted under
◦
conditions of 220 C and 2 MPa N
2
. The cellulose can be 100 % con-
verted with all catalysts while the carbon balance varied due to the
different degree of humins and coke formation. The products distribu-
tion of the as-obtained catalysts were displayed in Fig. 3. Besides the
desired product of LA, by-products including glucose, fructose, pyr-
uvaldehyde, HMF, LeA, and formic acid were also detected. In the
presence of the H-Beta, the yield of LA was low, approximately 6.3 %,
while the main products were the hydrolysis product of cellulose and the
further dehydration product, with glucose yield of 13.1 % and HMF of
(
Fig.4c), for the balance of the availability of active sites.
One issue associated with the practical application is the catalyst
Table 2
Catalytic conversion of various raw biomass feedstock. Reaction conditions:
◦
Biomass material 0.3 g, water 30 mL, catalyst 0.1 g, 240 C, 2 MPa N
2
, 60 min.
a
Element content
wt.%)
Component (wt.%)
2
2.7 %, together with a small amount of formic acid and LeA. The
LA yield
(
Substrate
b
presence of LeA and formic acid indicated the further hydration of HMF.
When Y was introduced into the deAl-Beta with loading from 1 % to 15
(
%)
C
H
N
cellulose
hemicellulose
lignin
%
, the LA yield was significantly improved from 19.5–51.6%, which was
Bamboo
Pine
47.8
46.7
41.7
6.6
6.8
6.0
0.1
0.1
0.5
46.0
44.6
39.9
19.3
14.9
18.7
21.5
25.4
16.8
75.9
60.8
44.0
in line with the increased surface acidities (Fig. S3). In contrast, the yield
of HMF was greatly reduced from 22.0%–5.6%. This result was plea-
surably competitive to the reported systems, as compared in Table 1.
The difference in the performance could be attributed to the internal
variation of Brønsted and Lewis acids in the catalysts. It was accepted
Rice
husk
a
Analyzed according to the procedures of the Van-Soest method [45].
Calculated based on C6 and C5 units contained in the raw biomass.
b
Fig. 4. Effect of a) temperature, b) time and c) catalyst amount on the conversion of cellulose over 10 %Y-Beta.
5

J. Ye et al.
Applied Catalysis A, General 619 (2021) 118133
adaptability to raw biomass feedstock. The complex structure of ligno-
cellulosic biomass consisting of cellulose, hemicellulose and lignin re-
stricts the efficiency of the cellulose hydrolysis reaction. The
performance of the catalysts for the conversion of lignocellulosic
Acknowledgements
This work was supported by the National Natural Science Foundation
of China (21808035); the Natural Science Foundation of Fujian Province
(2019J05058); the Fujian Provincial Department of Education
(JT180089, JT180343); the Quanzhou Department of Science and
Technology (2017YJY10); the Fundamental Research Funds of FJUT
(GY-Z18041, GY-Z20014).
◦
biomass into LA was evaluated over 10 % Y-Beta at 240 C for 60 min. To
our delight, as can be seen from Table 2, satisfactory LA yields were
obtained, with bamboo as high as 75.9 %, pine 60.8 %, and rice husk
4
4.0 % (based on the amount of C6 and C5 monosaccharide units con-
tained in the raw biomass feedstock, with more explanations in Cata-
lytic experiments and product analysis). It was also revealed that the
yield of LA was affected by the composition of biomass, especially
correlated with the content of cellulose and hemicellulose. The above
results indicated that the Y-Beta catalyst not only had outstanding ac-
tivity in converting cellulose into LA, but also performed well on
lignocellulose with more complex structure.
Appendix A. Supplementary data
Supplementary material related to this article can be found, in the
online version, at doi:https://doi.org/10.1016/j.apcata.2021.118133.
References
To verify the reusability of the catalyst, three consecutive reactions
were conducted with 10 %Y-Beta under the same reaction conditions
after catalyst recovery (Fig. S4). Between runs, the solid catalyst was
[
[
[
1] D.R. Dodds, R.A. Gross, Science 318 (2007) 1250–1251.
2] K. Li, Y. Sun, Chemistry 24 (2018) 18258–18270.
3] A. Corma, S. Iborra, A. Velty, Chem. Rev. 107 (2007) 2411–2502.
◦
◦
dried at 80 C overnight and calcined at 500 C for 2 h. After the second
use of the catalyst, the cellulose could still be fully converted, but the LA
yield dropped from 49.2–40.8%, while still slightly decreased to 37.3 %
in the third run. The ICP analysis of the used catalyst was conducted and
showed that the Y loading was reduced from 9.8 wt%to 6.3 wt% in the
second run. The resulting LA yield of 40.8 % was comparable to that on
fresh 5 % Y-Beta (40.1 %), indicating that the leaching of Y may be the
main reason for the deactivation of the used catalyst. In order to further
determine whether the dissolved Y species play the key catalytic role for
cellulose conversion, the fresh 10 %Y-Beta was treated in hot com-
[4] C. Mondelli, G. Gozaydin, N. Yan, J. Perez-Ramirez, Chem. Soc. Rev. 49 (2020)
3
764–3782.
5] V. Choudhary, A.B. Pinar, R.F. Lobo, D.G. Vlachos, S.I. Sandler, ChemSusChem 6
2013) 2369–2376.
[6] Y. Liao, Q. Liu, T. Wang, J. Long, L. Ma, Q. Zhang, Green Chem. 16 (2014)
305–3312.
7] N. Yan, C. Zhao, C. Luo, P.J. Dyson, H. Liu, Y. Kou, J. Am. Chem. Soc. 128 (2006)
[
(
3
[
8
714–8715.
[8] N. Shi, Q.Y. Liu, Q. Zhang, T.J. Wang, L.L. Ma, Green Chem. 15 (2013) 1967–1974.
[9] R.J. van Putten, J.C. van der Waal, E. de Jong, C.B. Rasrendra, H.J. Heeres, J.G. de
Vries, Chem. Rev. 113 (2013) 1499–1597.
[
[
10] S.M. Kang, J.X. Fu, G. Zhang, Renew. Sust. Energ. Rev. 94 (2018) 340–362.
11] Y. Liu, C. Luo, H. Liu, Angew. Chem. Int. Ed. Engl. 51 (2012) 3249–3253.
◦
pressed water at 220 C for 0.5 h and then filtered to get the filtrate
[12] A.A. Marianou, C.M. Michailof, A. Pineda, E.F. Iliopoulou, K.S. Triantafyllidis, A.
A. Lappas, Appl. Catal. A-Gen. 555 (2018) 75–87.
solution. The result showed that the yield of LA was only about 5% when
the recovered filtrate solution was used as reaction media, comparable
to that in the condition of absence of catalyst. It was indicated that the
reaction was heterogeneous catalysis. The stability of the catalyst would
continue to be improved in the future.
[
13] W. Deng, P. Wang, B. Wang, Y. Wang, L. Yan, Y. Li, Q. Zhang, Z. Cao, Y. Wang,
Green Chem. 20 (2018) 735–744.
[14] https://www.zionmarketresearch.com/sample/lactic-acidmarket).
[
15] A.A. Marianou, C.C. Michailof, D. Ipsakis, K. Triantafyllidis, A.A. Lappas, Green
Chem. 21 (2019) 6161–6178.
[
[
16] M.S. Holm, S. Saravanamurugan, E. Taarning, Science 328 (2010) 602–605.
17] S. Li, W.P. Deng, Y.Y. Li, Q.H. Zhang, Y. Wang, Int. J. Energ. Mater. Chem. Propuls.
3
2 (2019) 138–151.
4
. Conclusions
[
18] Y. Wang, W. Deng, B. Wang, Q. Zhang, X. Wan, Z. Tang, Y. Wang, C. Zhu, Z. Cao,
G. Wang, H. Wan, Nat. Commun. 4 (2013) 2141.
Herein, we successfully synthesized a Y modified Beta zeolite catalyst
[19] M. Orazov, M.E. Davis, P. Natl. Acad. Sci. U. S. A. 112 (2015) 11777–11782.
[
[
20] L. Yang, X. Yang, E. Tian, H. Lin, ChemSusChem 9 (2016) 36–41.
21] S.M. Coman, M. Verziu, A. Tirsoaga, B. Jurca, C. Teodorescu, V. Kuncser, V.
I. Parvulescu, G. Scholz, E. Kemnitz, ACS Catal. 5 (2015) 3013–3026.
for highly efficient conversion of cellulose to LA. It was confirmed that
the Brønsted acidities on the parent H-Beta resulted in the formation of
dehydration by-products. After dealumination and modification of Y,
the Brønsted acidities were removed and the Lewis acidic sites reformed,
which promoted the isomerization and retro-aldol reaction and led to
the selective production of LA. Over the 10 % Y-Beta, the cellulose can
be converted into LA with a yield of 49.2 % within 30 min, and the
substrate can be extended to bamboo powder, pine and other raw
biomass. Further attempts should be addressed to stabilize the Y species
confined within the zeolite matrix in water solution and promote the
recyclability of catalyst. These results possess a promise for the devel-
opment of biorefinery technology.
[22] P. Wattanapaphawong, P. Reubroycharoen, A. Yamaguchi, RSC Adv. 7 (2017)
18561–18568.
[
[
[
[
23] F.-F. Wang, J. Liu, H. Li, C.-L. Liu, R.-Z. Yang, W.-S. Dong, Green Chem. 17 (2015)
2
455–2463.
24] N. Shi, Q. Liu, X. He, H. Cen, R. Ju, Y. Zhang, L. Ma, Bioresour. Technol. Rep. 5
(2019) 66–73.
25] M. Xia, W. Dong, M. Gu, C. Chang, Z. Shen, Y. Zhang, RSC Adv. 8 (2018)
8
965–8975.
26] J. Dijkmans, M. Dusselier, D. Gabri ¨e ls, K. Houthoofd, P.C.M.M. Magusin, S. Huang,
Y. Pontikes, M. Trekels, A. Vantomme, L. Giebeler, S. Oswald, B.F. Sels, ACS Catal.
5
(2015) 928–940.
[
[
27] D. Yu, W. Dai, G. Wu, N. Guan, L. Li, Chinese J. Catal 40 (2019) 1375–1384.
28] F.-F. Wang, H.-Z. Wu, H.-F. Ren, C.-L. Liu, C.-L. Xu, W.-S. Dong, J. Porous Mater 24
(
2016) 697–706.
[
[
29] Y.Y. Sun, L. Shi, H. Wang, G. Miao, L.Z. Kong, S.G. Li, Y.H. Sun, Sustain. Energ.
Fuels 3 (2019) 1163–1171.
CRediT authorship contribution statement
30] X. Yang, Y. Zhang, L. Zhou, B. Gao, T. Lu, Y. Su, J. Xu, Food Chem. 289 (2019)
285–291.
Juan Ye: Methodology, Data curation, Investigation, Software.
Chenyu Chen: Software, Visualization. Ying Zheng: Resources. Dan
Zhou: Resources. Yunzhen Liu: Resources. Denglong Chen: Funding
acquisition. Liufang Ni: Methodology. Gang Xu: Conceptualization,
Methodology, Supervision. Fanan Wang: Writing - review & editing,
Project administration.
[
[
31] T. He, Z.C. Jiang, P. Wu, J. Yi, J.M. Li, C.W. Hu, Sci. Rep. 6 (2016) 38623.
32] M. Xia, Z. Shen, S. Xiao, B.-y. Peng, M. Gu, W. Dong, Y. Zhang, Appl. Catal. A-Gen.
5
83 (2019), 117126.
[33] W. Dai, S. Zhang, Z. Yu, T. Yan, G. Wu, N. Guan, L. Li, ACS Catal. 7 (2017)
3
703–3706.
34] T. Yan, W. Dai, G. Wu, S. Lang, M. Hunger, N. Guan, L. Li, ACS Catal. 8 (2018)
760–2773.
35] T.T. Yan, L. Yang, W.L. Dai, G.J. Wu, N.J. Guan, M. Hunger, L.D. Li, ACS Catal. 9
[
[
2
(
2019) 9726–9738.
Declaration of Competing Interest
[
[
36] S. Xu, Y. Wu, J. Li, et al., ACS Sustain. Chem. Eng. 8 (2020) 4244–4255.
37] S. Xu, J. Li, J. Li, Y. Wu, Y. Xiao, C. Hu, iScience 12 (2019) 132–140.
There are no conflicts to declare.
6

J. Ye et al.
Applied Catalysis A, General 619 (2021) 118133
[
[
[
[
38] P. Li, G. Liu, H. Wu, Y. Liu, J.-g. Jiang, P. Wu, J. Phys. Chem. C 115 (2011)
663–3670.
39] W.L. Dai, S.S. Zhang, Z.Y. Yu, T.T. Yan, G.J. Wu, N.J. Guan, L.D. Li, ACS Catal. 7
2017) 3703–3706.
40] H. Behner, J. Wecker, T. Matth ´e e, K. Samwer, Surf. Interface Anal. 18 (1992)
85–690.
41] M. Maache, A. Janin, J.C. Lavalley, J.F. Joly, E. Benazzi, Zeolites 13 (1993)
19–426.
[42] J. Pang, M. Zheng, X. Li, L. Song, R. Sun, J. Sebastian, A. Wang, J. Wang, X. Wang,
T. Zhang, ChemistrySelect 2 (2017) 309–314.
3
[43] M. Xia, W. Dong, Z. Shen, S. Xiao, W. Chen, M. Gu, Y. Zhang, Sustain Energ Fuels 4
(2020) 5327–5338.
(
[44] V.C. Nguyen, A. Dandach, T.T.H. Vu, P. Fongarland, N. Essayem, Mol Catal. 476
(2019) 110518.
[45] P.J. Van Soest, J.B. Robertson, B.A. Lewis, J. Dairy Sci. 74 (1991) 3583–3597.
6
4
7