Domino transformation of furfural to γ-valerolactone over SAPO-34 zeolite supported zirconium phosphate catalysts with tunable Lewis and Br?nsted acid sites

Article abstract of DOI:10.1016/j.mcat.2021.111538

The economic and highly efficient synthesis of γ-valerolactone (GVL) is being increasingly focused due to its wide applications in solvent, chemical, and fuel. Herein, a range of SAPO-34 supported zirconium phosphate (ZPS-X) catalysts were prepared for a facile one-pot conversion of furfural (FF) to GVL through a series of cascaded reactions involving transfer hydrogenation, etherification, alcoholysis and esterification. The introduction of zirconium phosphate renders the formation of relatively strong Lewis acid sites, and the amount of Lewis (L) and Br?nsted (B) acid sites of ZPS-X catalysts could be modified by adjusting the molar ratio of Zr to P (Zr/P ratio). Specifically, ZPS-1.0 having an appropriate Zr/P ratio with relatively strong L acid sites exhibited superior activity and selectivity for the production of GVL from FF.

Full text of DOI:10.1016/j.mcat.2021.111538

Molecular Catalysis 506 (2021) 111538
Contents lists available at ScienceDirect
Molecular Catalysis
journal homepage: www.journals.elsevier.com/molecular-catalysis
Domino transformation of furfural to γ-valerolactone over SAPO-34 zeolite
supported zirconium phosphate catalysts with tunable Lewis and Brønsted
acid sites
,
b
Weile Lia, Mengzhu Lia, Huai Liua, Wenlong Jiaa, Xin Yua, Shuai Wanga, Xianhai Zenga
,
,
,
,
,b
Yong Suna b, Junnan Weic **, Xing Tanga b,*, Lu Lina
a Xiamen Key Laboratory of Clean and High-valued Utilization for Biomass, College of Energy, Xiamen University, Xiang’an South Road, Xiamen, 361102, China
b Fujian Engineering and Research Center of Clean and High-valued Technologies for Biomass, Xiamen University, Xiang’an South Road, Xiamen, 361005, Fujian, China
c School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, No. 1 Wenyuan Road, Nanjing, 210046, China
A R T I C L E I N F O
A B S T R A C T
Keywords:
The economic and highly efficient synthesis of γ-valerolactone (GVL) is being increasingly focused due to its wide
applications in solvent, chemical, and fuel. Herein, a range of SAPO-34 supported zirconium phosphate (ZPS-X)
catalysts were prepared for a facile one-pot conversion of furfural (FF) to GVL through a series of cascaded
reactions involving transfer hydrogenation, etherification, alcoholysis and esterification. The introduction of
zirconium phosphate renders the formation of relatively strong Lewis acid sites, and the amount of Lewis (L) and
Brønsted (B) acid sites of ZPS-X catalysts could be modified by adjusting the molar ratio of Zr to P (Zr/P ratio).
Specifically, ZPS-1.0 having an appropriate Zr/P ratio with relatively strong L acid sites exhibited superior ac-
tivity and selectivity for the production of GVL from FF.
SAPO-34 zeolite
Zirconium phosphate
Tunable acidic sites
Furfural
γ-Valerolactone
1. Introduction
GVL is still largely limited by the cost-intensive synthesis of pure LA and
its esters [23]. It was known that furfural (FF) has already been effi-
Biomass, as the only renewable carbon resource on earth, can be
utilized for the production of a range of materials, chemicals and bio-
fuels, thereby alleviating the dependence of human society on fossil
energy [1–5]. With this background, biomass-derived platform mole-
cules, such as 5-hydroxymethylfurfural, levulinic acid (LA), and
γ-valerolactone (GVL), are considered as key intermediates [6–10]. The
safe and non-toxic GVL was served as an excellent and green solvent for
the fractionation of lignocellulose and many organic synthesis reactions
[11,12]. As a versatile biomass-derived platform molecule, GVL can be
converted into many value-added chemicals, such as 5-nonanone [13],
1,4-pentanediol [14], etc. Several biomass-derived polymeric mono-
ciently obtained from lignocellulosic biomass on an industrialized scale
[24–27], therefore, one-pot preparation of GVL from FF is a more
intriguing strategy [28,29]. However, the development of multifunc-
tional acid catalysts for the synthesis of GVL from FF with desirable
yields is a great challenge owing to the domino reactions including
transfer hydrogenation, etherification, hydrolysis and esterification as
well as inevitable side reactions to form humins involved (Scheme 1)
[30–33].
Based on the above challenge, only several works have been devoted
to design the catalysts or catalytic systems with appropriate distribution
of acidic sites for the conversion of FF to GVL (Table S1). For example,
mers, including
ε
-caprolactam and
α-methylene-γ-valerolactone [15,
Zhu et al. designed a noble-metal-based catalysts system (Au/
16], can also be produced from GVL. More interestingly, value-added
liquid alkenes fuels can be synthesized from GVL by consecutive
ring-opening and hydrodeoxygenation [17,18].
ZrO2+ZSM-5) and gave a GVL selectivity of 80.4 % with a complete
conversion of FF at 120 ◦C for 24 h using 2-propanol as H-donor. In this
case, highly dispersed Au nanoparticles over ZrO2 support and ZSM-5
zeolite brought the appropriate amount of L and B acid sites, respec-
tively, resulting in the excellent catalytic performance [34]. Besides,
It has been reported that GVL could be produced from LA and its
esters with desirable yields [7,19–22], but the industrial production of
* Corresponding author at: Xiamen Key Laboratory of Clean and High-valued Utilization for Biomass, College of Energy, Xiamen University, Xiang’an South Road,
Xiamen, 361102, China.
** Corresponding author.
E-mail addresses: junnan_wei@outlook.com (J. Wei), x.tang@xmu.edu.cn (X. Tang).
https://doi.org/10.1016/j.mcat.2021.111538
Received 11 January 2021; Received in revised form 18 March 2021; Accepted 19 March 2021
Available online 5 April 2021
2468-8231/© 2021 Elsevier B.V. All rights reserved.

W. Li et al.
Molecular Catalysis 506 (2021) 111538
Scheme 1. Proposed reaction pathway for the conversion of FF to GVL in isopropanol; [1] & [4] Transfer hydrogenation (catalyzed by Lewis acid) [2]; Etherification
(catalyzed by Lewis or Brønsted acid) [3]; Alcoholysis (catalyzed by Brønsted acid) [5]; Cyclization (catalyzed by Brønsted acid).
non-precious metals, such as Sn, Zr and Al are also active metal sites for
the tandem reactions during the conversion of FF to GVL. Bui et al.
established a non-noble metal system composed of Al-MFI-ns and
Zr-beta, which was employed to catalyze the tandem conversion of FF to
GVL, and a GVL yield of 78 % was obtained in 2-butanol/water under
120 ◦C for 48 h [35]. Nevertheless, a multifunctional catalyst capable of
catalyzing the integrated transformation of FF to GVL is a more
appealing choice, owing to it is available in catalyst recycling. In this
light, Winoto et al. prepared a Sn-Al-Beta bimetallic zeolite catalyst for
the direct conversion of FF to GVL, which offered 60.5 % GVL yield in
2-butanol (180 ◦C, 24 h) [33]. In order to further improve GVL yield,
they also prepared HPW/Zr-Beta as the catalysts and used isopropanol as
the H-donor instead of 2-butanol, finally achieved near 70 % yield of
GVL at the milder reaction conditions (160 ◦C, 24 h) [36]. Compared
with Sn-Al-beta, HPW/Zr-Beta possessed more abundant B acid sites,
which promote alcoholysis of isopropyl levulinate (IPL). Additionally,
Zr-Al-beta mesoporous catalyst was designed and prepared by Song et al.
for the direct synthesis of GVL from FF in isopropanol, providing the
highest GVL yield up to 90 % at 120 ◦C for 48 h [37]. In this case, the
acidic sites over meso-Zr-Al-beta catalysts were tuned efficiently
through acid-alkali treatment during the preparation of the catalyst,
facilitating the selective synthesis of GVL from FF. However,
meso-Zr-Al-beta still suffered from low catalytic efficiency (48 h) [37].
Both L and B acids are needed for the production of GVL from FF
(Scheme 1), thus the key to improve the conversion efficiency of FF into
GVL with an attractive yield is the design of multifunctional catalysts or
catalytic systems with the appropriate spread of L and B acidic sites.
However, the strategy and mechanism about the regulation of L and B
acidic sites needs to be further investigated.
2. Experimental
2.1. Materials
Furfural (FF, 98 %), furfuryl alcohol (FA, 98 %), γ-valerolactone
(GVL, 98 %), ZrOCl2.8H2O (99 %) and NH4H2PO4 (99 %) were pur-
chased from Aladdin Reagent Co. Ltd. (Shanghai, China). Zeolite SAPO-
34 was purchased from Tianjin Nankai catalyst co. LTD (Tianjin, China).
Ethanol (99 %), n-propanol (99 %), n-butanol (99 %), isopropanol (99
%), isobutanol (99 %) and ammonia (25–28 %) were bought by Sino-
pharm Chemical Reagent Co. Ltd. (Shanghai, China). Furfuryl ether (FE,
98 %) was supplied from Yuanye Biotechnology Co. Ltd. (Shanghai,
China). Isopropyl levulinate (IPL, 97 %) was provided by Meryer
chemical Technology Co. Ltd (Shanghai, China).
2.2. Catalyst preparation
A series of SAPO-34 supported zirconium phosphate catalysts were
donated as ZPS-X, where the X represents the molar ratio of zirconium to
phosphorus, namely Zr/P molar ratio. Note that the actual Zr/P ratio is
lower than the “X” value of ZPS-X catalysts due to the existence of P in
support SAPO-34 zeolite (as exhibited in Table 2). The molar ratio of Zr
to P in the catalyst was adjusted by changing the amount of Zr precursor
under the condition of keeping the P precursor (NH4H2PO4) unchanged.
A typical procedure for the preparation of ZPS-1.0 was as follows, 1.4 g
ZrOCl2⋅8H2O was dissolved in 8.8 mL deionized water under magnetic
stirring, then dropwise adding 4.4 mL solution of NH4H2PO4 (1 mol/L).
Subsequently, 1.5 g SAPO-34 powder was transferred into the above-
mentioned mixed solution. The solution was stirred vigorously for 4 h
at room temperature and then aged for 8 h. The resultant suspension was
separated by a filter and washed with 600 mL deionized water. After-
wards, the recovered solid was dried overnight at 105 ◦C and calcined at
400 ◦C for 4 h at a heating rate of 5 ◦C/min in air.
SAPO-34 zeolite, one of the nanoporous materials [38,39], possesses
uniform microporosity, excellent specific surface area and high thermal
and chemical stabilities [40–43]. Moreover, owing to its silicoalumi-
nophosphate composition [44], it also has suitable acid properties that
make it a relatively high catalytic performance for methanol-to-olefin
conversion, hydrogenation and oxidation reactions [42,45–47]. Addi-
tionally, Zirconium phosphate is an environmentally benign material
with adjustable L and B acid sites [48,49]. In this work, microporous
SAPO-34 zeolite supported zirconium phosphate (ZPS-X) catalysts were
designed for the domino conversion of FF to selectively synthesize GVL.
The introduction of zirconium phosphate boosted the acid sites of ZPS-X
catalysts. And the distribution of L and B acid sites over ZPS-X catalysts
could be flexibly tuned by regulating the dosage of Zr precursor
(ZrOCl2⋅8H2O). When the Zr/P ratio of ZPS-X was adjusted to 1.0, the
resulting ZPS-1.0 catalyst that possessed appropriate L and B acidity
facilitated the continuous transfer hydrogenation and alcoholysis re-
actions, achieving a desirable GVL yield (80 %) from FF at 150 ◦C for 18
h (or at 170 ◦C for 6 h) using isopropanol as H-donor.
The preparation method of ZrPO sample, of which the Zr/P was 1.0,
was as follows, NH4H2PO4 solution (1.0 mol/L) of 8.8 mL was firstly
added into ZrOCl2⋅8H2O solution (0.5 mol/L) of 4.4 mL. Subsequently,
the mixed solution was magnetically stirred for 4 h and aged for 8 h.
Then the resulting precipitates were treated through the tandem unit
operations including filtration, washing, drying and calcination. The
above unit operations were performed according to the prepared
method of ZPS-1.0.
The preparation method of Zr/SAPO-34 sample was as follows, 1.4 g
ZrOCl2⋅8H2O was dissolved in 8.8 mL deionized water, then dropwise
adding the adequate NH3⋅H2O solution with magnetic stirring for 4 h
and then aged for 8 h. Then, 1.5 g SAPO-34 powder was added into the
mixed solution. The subsequent steps are identical to the preparation of
ZPS-1.0.
2.3. Catalyst characterization
The X-ray diffraction (XRD) analysis was performed on a Panalytical
X’pert Pro diffractometer with the parameters: 40 kV, 30 mA, 2θ =
2

W. Li et al.
Molecular Catalysis 506 (2021) 111538
20~80◦, scanning speed = 10◦/min, resolution = 0.02◦.
The scanning electron microscope (SEM) images were gained using
SUPRA 55 electron microscope operated on 5 kV teating voltage. The
high resolution transmission electron microscope (HRTEM) measure-
ments were collected by a JEM-2100 electron microscope with 200 kV
testing voltage.
The N2 adsorption-desorption analysis was recorded on a Micro-
meritics ASAP 2020 HD88 physisorption analyzer. To remove moisture
and impurities, the samples were performed degassing treatment under
vacuum before analysis. The surface area, pore size and average pore
diameter were measured by Barrett-Joyner-Halenda (BJH) algorithm
and model.
The temperature-programmed desorption of ammonia (NH3-TPD)
experiments was evaluated by a Micromeritics AutoChem 2920 chemi-
sorption analysis module. The samples were firstly degassed at 200 ◦
C
for 30 min, then cooling to 100 ◦C under Ar flow (20 mL/min), NH3 was
introduced for 30 min and then purged with He for 2 h. The samples
were treated in the scope of 100 ◦C ~ 850 ◦C with a heating speed of 10
Fig. 1. XRD patterns of (a) SAPO-34, (b) ZrPO, (c) Zr/SAPO-34, (d) ZPS-0.5, (e)
◦C minꢀ 1
.
ZPS-1.0, and (f) ZPS-2.0.
The ex-situ Diffuse reflectance infrared Fourier transform spectra
(DRIFTS) were determined by Thermo Fisher Nicolet Is10 spectrometer.
Before the measurement, all the samples were treated at 450 ◦C for 1 h to
eliminate the adsorbed water. DRIFTS were recorded in the scope of
4000–3200 cmꢀ 1 and using KBr spectrum as the background.
FF m olar am ount in products
FF conversion (%) = (1-
Yield of Product (%) =
) × 100%
(1)
(2)
(3)
the initial FF m olar am ount
Product m olar am ount in products
the initial FF m olar am ount
× 100%
The pyridine-adsorbed Fourier transform infrared spectroscopy (Py-
FTIR) using the Bruker Tensor 27 to determine the Brønsted and Lewis
acid sites. The samples were managed at 350 ◦C for 4 h in vacuum. When
the samples were cooled down to room temperature, then pyridine was
injected to the analysis module for 20 min and then emptied the pyri-
dine. Finally, the samples were heated to 350 ◦C, and the spectra were
recorded under this given temperature.
Yield of Product
FF conversion
Selectivity of Product (%) =
× 100%
3. Results and discussion
3.1. Catalyst characterization
3.1.1. X-ray diffraction
The x-ray photoelectron spectroscopy (XPS) analysis was imple-
mented on a Thermo ESCALAB 250Xi electron spectrometer with a
monochromatic Al/Kα (hν = 1486.6 eV). All of the binding energies
were calibrated by C1 s line of 284.6 eV.
X-ray diffraction (XRD) patterns of SAPO-34 zeolite and a set of
synthesized Zr/P containing samples were shown in Fig. 1. Pure SAPO-
34 zeolite displayed a set of diffraction peaks at 13.0◦, 16.2◦, 17.8◦,
20.9◦, 24.9◦, 26.4◦, 30.6◦ and 31.0◦, which related to the chabazite
crystal structure corresponding to PDF.47-0630 [50]. There were no
obvious diffraction peaks of the ZrPO sample, indicating the amorphous
structure of the synthesized zirconium phosphate. The Zr modified
SAPO-34 catalysts still display the similar diffraction peaks with respect
to SAPO-34 zeolite. As for the ZPS-X catalysts, the strength of diffraction
peaks of SAPO-34 declined gradually with the increase of Zr/P ratio.
Especially, when the Zr/P ratio increased to 2.0, almost no characteristic
peak assigned to SAPO-34 was visible in the profiles of ZPS-2.0,
implying that the crystal of SAPO-34 zeolite suffered destruction
owing to the excess introduction of zirconium species [51]. In addition,
the XRD profiles of these samples before and after calcination processed
almost the same diffraction peaks (Fig. S1), demonstrating that the
calcining process has no significant impact on the crystal form of these
samples and the crystal of SAPO-34 in ZPS-2.0 should be destroyed
before calcination.
Elemental analysis was measured by an Elementar Vario EL III in-
strument (Elemen-tar Analysensysteme GmbH, Germany)
The inductively coupled plasma-mass spectrometry (ICP-MS) was
conducted by Agilent 7500 with the parameters: radio frequency power
= 1.5 KW, plasma gas flow rate = 15 L/min, nebulizer gas flow rate =
1.1 L/min, nebulizer pump = 0.1 rps, sample depth = 8.6 mm, sample
inlet flow rate = 1 mL/min. The inductively coupled plasma-atomic
emission spectrometry (ICP-AES) was carried out by 7400 Thermo Sci-
entific with the parameters: radio frequency power = 1.6 kW, 40 MHz,
plasma gas flow rate = 15 L/min, auxiliary gas flow rate: 1.5 L min ꢀ 1,
nebulizer pressure = 200 kPa, pump rate = 10 mL/min.
2.4. Catalytic reaction and product analysis
The experiments about the transformation of FF to GVL were per-
formed in a 50 mL autoclave with an external temperature heating
jacket and magnetic stirring. In the typical procedure, 192 mg of cata-
lyst, 0.05 mol/L furfural, 20 mL isopropanol were loaded in the auto-
clave and then sealed. Prior to place into a heating jacket, N2 was
injected and purged 4 times to absolutely remove air within the reactor.
The temperature and stirring controller were then turned on for heating
and stirring processes. After the reaction was maintained for the ex-
pected time at a stirring speed of 800 rpm, the autoclave was cooled to
room temperature in a flowing water. The used catalyst was recovered
by filtration and washed using isopropanol for 3 times (3 mL for each
time), then drying at 105 ◦C for 6 h to applicate in recyclability tests.
Qualitative and quantitative analysis of liquid phase was determined
by gas chromatograph-mass spectrum (GC–MS) and a GC-7890 Agilent
series (GC), respectively. The FF conversion, product yield and selec-
tivity were computed from equations 1~3, respectively.
3.1.2. Surface morphology and structure
The surface morphology of SAPO-34, Zr/SAPO-34 and ZPS samples
were illustrated by scanning electron microscope (SEM) images in Fig. 2.
As shown in Fig. 2a and b, SAPO-34 zeolite was comprised of cubic
particles with a uniform size of 1~3 μm and a smooth surface [52].
Zr/SAPO-34 possessed the similar micromorphology with respect to
pure SAPO-34 zeolite, which illustrated that the basic framework of
SAPO-34 remained unchanged after the adhesion of Zr species using
ammonium hydroxide as precipitant (Fig. 2c). Notably, as for ZPS-X
catalysts, the surface of SAPO-34 particles became porous and the
number of holes increased with Zr/P ratio (Fig. 2d and f). During the
preparation of ZPS-X catalysts, the aqueous solution exhibited acidic
3

W. Li et al.
Molecular Catalysis 506 (2021) 111538
Fig. 2. SEM images of (a, b) SAPO-34, (c) Zr/SAPO-34, (d) ZPS-0.5, (e) ZPS-1.0, and (f) ZPS-2.0.
Fig. 3. TEM images of the catalysts: (a) SAPO-34, (b) ZPS-1.0, (c) ZrPO.
Table 1
Table 2
Textural properties of different catalysts.
Distribution of Lewis and Brønsted acid sites of different catalysts.
Entry
Catalyst
SBETa, m2/g
Vporeb, cm3/g
Dporec, nm
Entry
Catalyst
Zr/Pa
L acidb,
μmol/g
B acidb,
μ
mol/g
L/B ratio
1
2
3
4
5
6
SAPO-34
ZrPO
602
240
416
424
402
290
0.33
0.59
0.52
0.48
0.43
0.17
1.90
9.66
6.40
10.1
5.44
3.26
1
2
3
4
5
6
SAPO-34
ZrPO
–
73.6
178.0
104.5
41.3
87.1
76.3
11.9
45.9
12.2
15.3
26.8
29.7
6.18
3.9
–
Zr/SAPO-34
ZPS-0.5
ZPS-1.0
ZPS-2.0
Zr/SAPO-34
ZPS-0.5
ZPS-1.0
ZPS-2.0
–
8.57
2.70
3.25
2.57
0.19
0.36
0.74
a
b
c
a
b
BET surface area.
Zr/P molar ratio was determined by ICP-MS results.
total pore volume measured at P/P0 = 0.9999.
the amount of Lewis/ Brønsted acid sites was calculated by fitting decon-
average pore width calculated by BJH method.
volution of peaks assigned to Lewis/Brønsted acid in Fig. 4B.
after the addition of NH4H2PO4, probably giving rise to the formation of
holes on the surface of ZPS-X catalysts [53]. For instance, if increasing
the dosage of Zr Precursor (ZrOCl2) to prepare ZPS-2.0, stronger acidity
was detected in the aqueous solution, aggravating the destruction of
SAPO-34 crystal particles (Fig. 2f). Besides, The SEM mapping images of
ZPS-1.0 showed the fairly homogeneously dispersion of Zr and P species
(Fig. S2), which means these species were successfully loaded on the
SAPO-34 support. Transmission electron microscope (TEM) images of
SAPO-34, ZPS-1.0 and ZrPO samples were also shown in Fig. 3. As can be
seen from Fig. 3b, cubic particles are SAPO-34 zeolite (the square area
marked red), indicating that the original structure of SAPO-34 was
maintained after the loading of zirconium phosphate. On the other hand,
there are the amorphous clusters around SAPO-34, which should be
zirconium phosphate agglomerates.
3.1.3. N2 adsorption-desorption
The N2 adsorption and desorption isotherms of SAPO-34, Zr/SAPO-
34, ZrPO and ZPS-X catalysts were depicted in Fig. S3. All samples
exhibited typical type IV isotherms with H3-type (Zr/SAPO-34, ZrPO,
ZPS-0.5, ZPS-1.0) or H4-type (SAPO-34, ZPS-2.0) hysteresis loops cor-
responding to IUPAC classification [54,55]. These indicated that all
studied materials were composed of platelike particles or assemblages of
slit-shaped pores [56]. Table 1 summarizes the textural properties of
SAPO-34, Zr/SAPO-34 and ZPS-X samples, including specific surface
area, average pore diameter, and total pore volume. SAPO-34 had the
highest BET surface of 602 m2/g with a relatively low pore volume (0.33
cm3/g) and average pore size (1.90 nm) (Table 1, entry 1). In contrast,
ZrPO possessed the lowest BET surface area of 240 m2/g with a rela-
tively high pore volume (0.59 cm3/g) and average pore size (9.66 nm)
(Table 1, entry 2). If ZrO2 and zirconium phosphate was introduced to
4

W. Li et al.
Molecular Catalysis 506 (2021) 111538
good agreement with the characterizations of XRD and SEM.
3.1.5. Surface acidic property
The acidic property of the SAPO-34, ZrPO, Zr/SAPO-34 and ZPS-X
catalysts was determined by NH3 temperature-programmed desorption
(NH3-TPD). As shown in Fig. 5A, compared to the ZrPO sample, the
desorption peak of ZPS-X tends to shift to the higher temperature, and
this phenomenon becomes more obvious with the increase of Zr/P ratio.
Additionally, it can be observed from Fig. S4 that each sample exhibited
broad profiles in the range of 100~550 ◦C, indicating the existence of
weak (150 ◦C), moderate (300 ◦C) and strong (400 ◦C) acid sites,
respectively. As for the SAPO-34 zeolite, the low-temperature peaks
–
ascribed to weak acidic sites are formed by hydroxyl groups (P OH,
Siꢀ OH and Alꢀ OH) on the surface [61,62], while the high-temperature
peak assigned to the moderate and strong acidic sites are resulted from
Siꢀ OH–Al groups [40]. In comparison with SAPO-34, ZrPO and
Zr/SAPO-34 possessed comparatively fewer weak acidic sites and a
wider temperature range of moderate and strong acidic sites. Compared
with Zr/SAPO-34, ZPS-X catalysts had weaker acid sites and fewer
moderate/strong acid sites. This is because that the source of acid sites
over ZPS-X catalysts (mainly formed by zirconium phosphate) is
different from Zr/SAPO-34 (mainly formed by zirconia).
Fig. 4. Ex-situ DRIFTS spectra of catalysts: (a) SAPO-34, (b) ZPS-0.5, (c) ZPS-
1.0 and (d) ZPS-2.0.
SAPO-34 support, respectively, the BET surface of Zr/SAPO-34 and
ZPS-0.5 remarkably decreased to 416 m2/g and 424 m2/g (Table 1,
entries 3 and 4). And as for ZPS-0.5, ZPS-1.0 and ZPS-2.0, the Dpore all
between the 2ꢀ 50 nm range assigned to mesoporous materials. The
disappearance of microporosity for ZrPO supported on SAPO-34 is
probably attributed to the cover of ZrPO species over SAPO-34, resulting
in the block of micropores in the SAPO-34.When the ratio of Zr/P
increased to 1.0, the BET surface and total pore volume of the ZPS-1.0
were almost unchanged compared to that of ZPS-0.5. However, if the
ratio of Zr/P further raised to 2.0, the BET surface and total pore volume
of the ZPS-2.0 remarkably decreased to 290 m2/g and 0.17 cm3/g
(Table 1, entry 6), possibly due to the destruction of crystal structure of
SAPO-34 (Figs. 1 and 2).
To gain more information about the acidic species of these studied
catalysts, Fourier transform infrared spectra of adsorbed pyridine (Py-
FTIR) were conducted. As exhibited in Fig. 5B, the bands at 1445 cmꢀ 1
and 1610 cmꢀ 1 were assigned to the adsorption of pyridine on Lewis
acid sites, which were produced by Zr-O-P bond or unsaturated coor-
dination zirconium [63]. The vibration at 1545 cmꢀ 1 was produced by
the adsorption of pyridine on the Brønsted acid sites formed by
Siꢀ OH-Al and -P(OH)n (n = 1, 2) [64]. The peak at 1490 cmꢀ 1 was the
simultaneous adsorption of pyridine on B and L acid sites [65]. The
amount of L and B acid sites was calculated by fitting deconvolution of
peaks around 1445 and 1545 cmꢀ 1, respectively, and the results were
listed in Table 2. SAPO-34 zeolite possessed moderate amount of L acid
3.1.4. Ex-situ DRIFT analysis
(73.6
1). Notably, ZrPO displayed an abundance of L acid sites (178.0
and B acid sites (45.9 mol/g) (Table 2, entry 2). If ZrO2 was supported
over SAPO-34 to give Zr/SAPO-34, the Lewis acid sites have been largely
increased to 104.5 mol/g with no significant changes in B acid sites
(12.2
μ
mol/g) with small amount of B acid (11.9
μ
mol/g) (Table 2, entry
To further investigate the structure collapse of SAPO-34 support after
the introduction of zirconium phosphate, ex-situ diffuse reflectance
infrared Fourier transform spectroscopy (DRIFTS) spectra measure-
ments were carried out. As exhibited in Fig. 4, the bands situated at 3600
cmꢀ 1 and 3626 cmꢀ 1 were assigned to the hydroxyls from Siꢀ OH-Al
species [52]. The bands at 3675 cmꢀ 1 and 3730 cmꢀ 1 were related to the
μ
mol/g)
μ
μ
μ
mol/g), compared with SAPO-34 parent (Table 2, entries 1 and
3). When the SAPO-34 zeolite was loaded with zirconium phosphate, the
amount of L acid sites over ZPS-X catalysts raised firstly from 41.3
–
surface hydroxyls from Siꢀ OH and Alꢀ OH (P OH) species, respec-
tively [57]. The band intensity of the Brønsted and surface hydroxyls
decreased with increasing Zr content, suggesting the partial structural
failure of SAPO-34 support during the preparation of the catalyst
[58–60]. Especially, when the Zr/P ratio of ZPS-X increased to 2.0, the
band intensity of the hydroxyls became much weaker as compared to
SAPO-34 support and other ZPS-X catalysts. The above observation is in
μ
mol/g for ZPS-0.5–87.1
μmol/g for ZPS-1.0 and then slightly dropped
to 76.3
μ
mol/g for ZPS-2.0 (Table 2, entries 1 and 4~6). In comparison,
B acid sites over ZPS-X steadily enhanced from 15.3–29.7 μmol/g with
the increasing Zr/P ratio from 0.5 to 2.0. In this respect, both ZPS-1.0
and ZPS-2.0 possessed moderate amount of L and B acid sites, as
compared to ZrPO and SAPO-34. Especially, ZPS-1.0 displayed a
Fig. 5. A) NH3-TPD profiles and B) Py-FTIR spectra of (a) SAPO-34, (b) ZrPO, (c) Zr/SAPO-34, (d) ZPS-0.5, (e) ZPS-1.0 and (f) ZPS-2.0; L: Lewis acid, B:
Brønsted acid.
5

W. Li et al.
Molecular Catalysis 506 (2021) 111538
Fig. 6. XPS spectra of Zr 3d, O 1s and P 2p: (a) Zr/SAPO-34, (b) ZrPO, (c) ZPS-0.5, (d) ZPS-1.0, and (e) ZPS-2.0.
moderate ratio of L/B (3.25), as compared to other catalysts. One can
thus conclude that the distribution of L and B acid sites could be effec-
tively adjusted by the combination of ZrPO and SAPO-34 zeolite with
different Zr/P ratios.
reason might be that the amounts of high-electron-density Zr-O-Zr bonds
have risen gradually with the increase of Zr/P, which is also known to
effectively regulate the zirconium Lewis acidity by adjusting Zr/P ratio
[68–70], in line with the NH3-TPD analysis. The effect of Zr/P ratio on
the P 2p binding energy of ZPS-X catalysts showed a similar trend. A
negative shift of P 2p binding energy was found with increasing Zr/P
ratio, which is probably associated with the enhanced electron transfer
from Zr to P with the increment of Zr species. The O 1s peak of all
samples exhibited a broad and asymmetric peak [71]. For instance, O 1s
profile of ZPS-1.0 could be fitted by three Gaussian peaks at binding
energies of 531.3 eV, 532.1 eV and 533.0 eV, which attributed to Zr-O-Zr
3.1.6. XPS analysis
The components and chemical states of elements on the surface of
catalysts were characterized by X-ray photoelectron spectroscopy (XPS).
The XPS survey spectra of ZrPO, Zr/SAPO-34 and ZPS-X were exhibited
in Fig. S5, indicating the existence of Zr, P and O elements in all these
samples.
–
– –
[72], P-O-Zr (as well as P O, Zr-O-H) [64] and P O H [73], respec-
–
The XPS curves of Zr 3d, O 1s and P 2p of all these samples were
shown in Fig. 6. There were two peaks of Zr 3d3/2 and Zr 3d5/2 corre-
sponding to the characteristic peaks of tetravalent Zr [66]. The binding
energy of Zr 3d for ZrPO catalyst shifted to higher values in comparison
with Zr/SAPO-34, indicating the former had stronger Lewis acid sites.
The shift may be explained by the difference of electron density around
Zr between Zr-O-P and Zr-O-Zr [67]. P with higher electronegativity
given rise to a shift of electron density from Zr to P centers, thus the
electron density of Zr in Zr-O-P (ZrPO) is lower than that in Zr-O-Zr
(Zr/SAPO-34). As for the ZPS-X catalysts, with the increase of Zr/P
ratio, the binding energy of Zr 3d moved gradually to lower values. The
tively. Note that the O 1s peak of SAPO-34 was overlapped with the
above last two Gaussian peaks. Compared to Zr/SAPO-34, the binding
energy of O 1s for ZPS-X catalysts shifted to the higher values, which can
–
be attached to the formation of Zr-O-P and P O bonds on the surface of
–
SAPO-34 zeolite [74]. Similar to the binding energy of Zr 3d and P 2p,
the binding energy of O 1s in ZPS-X also decreased with the increase of
Zr/P ratio. This phenomenon may due to the increase of electron density
of oxygen with zirconium content [66]. To sum up, the formation of
Zr-O-P has a significant influence on the distribution of elemental
electron density on the surface of ZPS-X catalysts, and thus the strength
of Lewis acid could be turned by adjusting the Zr/P ratio.
Table 3
One-pot conversion of FF into GVL over different catalysts.
3.2. Reaction pathway
Entry
Catalyst
XFF,%
SIPL,%
SGVL,%
SIPL+GVL,%
1
2
3a
4
5
6
7
SAPO-34
ZrPO
40.5
100
100
100
86.5
100
100
94.1
11.3
0
0
94.1
34.6
32.0
45.2
76.0
85.7
66.9
A possible reaction pathway for the transformation of FF to GVL over
L and B acidic sites was described in Scheme 1 [33,75–78]. First, the
carbonyl group of FF was reduced using isopropanol as H-donor to
produce FA through the transfer hydrogenation over L acid sites. The
generated FA could be further etherified with isopropanol over L or B
acid sites to form furfuryl ether (FE). Afterwards, the alcoholysis of FE to
IPL could occur over Brønsted acid sites of catalysts. Subsequently, L
acid sites could also catalyze the formation of isopropyl 4-hydroxyvaler-
ate (IPHV) from IPL via the transfer hydrogenation. IPHV is an instable
intermediate product that could be facilely converted to GVL in the
23.3
32.0
34.8
14.5
65.1
59.5
ZrPO + SAPO-34
Zr/SAPO-34
ZPS-0.5
10.2
61.5
20.6
7.4
ZPS-1.0
ZPS-2.0
Reaction conditions: 0.05 mol/L FF, 20 mL 2-propanol, 0.192 g catalyst, 150 ◦C,
10 h and N2 at atmospheric conditions.
a
The used catalyst was been mixed physically in measured proportions by
ICP-MS.
6

W. Li et al.
Molecular Catalysis 506 (2021) 111538
presence of B acid sites [79–81]. Due to the IPHV owning the active
hydroxyl group that it could also be etherified or dehydrated into other
by-products [82]. In addition, humins is easily produced from FF or FA
in the reaction process if there are excessive acid sites over the catalysts
[30,33]. Therefore, the design of catalysts with appropriate L and B acid
sites is the key for the selective synthesis of GVL from FF.
Table 4
Conversion of FF to GVL using different alcohol as the H-donor.
Entry
Solvent
△Ho f,
steric hindrance,
kcal/mol
XFF
,
SGVL
,
SAL
%
,
kJ/mol
%
%
1
2
3
4
5
ethanol
85.4
87.3
79.7
70.0
69.3
2.813
3.777
4.688
4.116
5.312
89.6
6.6
0.0
37.6
30.4
0.0
n-propanol
n-butanol
isopropanol
isobutanol
72.5
82.9
21.8
80.4
60.0
100.0
100.0
0.0
3.3. Catalytic performance of catalysts
0.0
Reaction conditions: 0.05 mol/L FF, 20 mL alcoholic solvent, 0.192 g ZPS-1.0,
150 ◦C, 18 h and N2 at atmospheric conditions.
The catalytic performance of the prepared catalysts was evaluated at
423 K in 10 h using isopropanol as H-donor and solvent. As shown in
Table 3, a FF conversion of only 40.5 % with an IPL selectivity of 94.1 %
was offered in the presence of pure SAPO-34 zeolite (Table 3, entry 1),
suggesting that SAPO-34 probably lacks of strong L acid sites for the
conversion of FF to IPL or GVL. In addition, a small amount of B acid
Table 5
Conversion of FF to GVL in 2-propanol under different reaction conditions.
Select., %
sites (11.9 μmol/g, Table 2) over SAPO-34 is also detrimental to the
Entry
Temp., ◦
C
Time, h
LA conv., %
alcoholysis of FA to IPL. ZrPO and Zr/SAPO-34 offered a quantitative
conversion of FF, although the GVL selectivity of only 23.3 % or 34.8 %
was achieved under the experimental conditions (Table 3, entries 2 and
4), respectively. The poor GVL selectivity at a full FF conversion is
FE
IPL
GVL
1
2
3
4
5
6
7
8
9
150
150
150
150
150
150
140
160
170
2
53.0
68.7
32.5
0.0
16.5
40.1
20.6
11.7
0.0
10.0
15.0
65.1
69.6
80.0
65.0
19.9
65.0
80.0
6
81.2
10
14
18
22
6
100.0
100.0
100.0
100.0
68.3
0.0
probably attributed to the excessive B acid sites over ZrPO (45.9 μmol/g,
0.0
Table 2) that facilitated the polymerization of FA to form polymers or
0.0
0.0
humins and insufficient B acid sites over Zr/SAPO-34 (12.2
Table 2) that can not generate GVL [30,33].
μmol/g,
27.8
0.0
40.0
0.0
6
100.0
100.0
6
0.0
0.0
Moreover, the GVL selectivity was 32 % over the catalysts that was
mixed physically (Table 3, entry 3). Surprisingly, the GVL selectivity
significantly raised to 65.1 % by the ZPS-1.0 catalyst (Table 1, entry 7).
So, the catalytic performance was largely improved when used the zir-
conium phosphate supported on SAPO-34 zeolite as the catalyst. Inter-
estingly, as for the ZPS-X catalysts, GVL selectivity firstly increased from
14.5%–65.1%, and then slightly decreased to 59.5 % with the Zr/P ratio
increasing from 0.5 to 2.0 (Table 3, entries 4–6). The above observation
is in good line with the trend of L acid sites over ZPS-X with different Zr/
P ratio (Table 2). Notably, ZPS-1.0 and ZPS-2.0 displayed similar L and B
acid (Table 2), but ZPS-1.0 gave a higher total selectivity of IPL and GVL
(86.5 %) than that of ZPS-2.0 (66.9 %) (Table 3, entries 5–6). Thus, the
low specific surface area of ZPS-2.0 (290 m2/g versus 402 m2/g for ZPS-
1.0, Table 1) should responsible for its relatively poor catalytic perfor-
mance as compared to ZPS-1.0. On the other hand, ZPS-1.0 with rela-
tively low L acid sites showed the best catalytic performance for the
conversion of FF to GVL, however, ZrPO and Zr/SAPO-34 having an
abundance of L acid sites only gave a total selectivity of IPL and GVL
lower than 50 % (Tables 2–3). Given the domino conversion of FF to GVL
involves several reaction units including transfer hydrogenation, alco-
holysis and cyclization (Scheme 1), which have diverse demand for L or
B acid. For instance, alcoholysis and cyclization reactions require the
catalyst containing B acid sites [33,79]. However, an excess of B acid
sites could largely promote the side reaction of FF and FA to form
humins [30]. Therefore, the ratio of L to B acid (L/B ratio) is of crucial
importance to the selective transformation of FF to GVL. In this light,
one can thus infer that ZPS-1.0 possessed an appropriate L/B ratio of
3.25 for the effective conversion of FF to GVL (Tables 2 and 3). Addi-
tionally, the stronger Lewis acid over ZPS-1.0 than that of ZrPO and
Zr/SAPO-34 also likely promoted the conversion of FF to GVL (Fig. 5).
In conclusion, the above experimental results disclose that the
catalyst containing an appropriate L/B ratio with relatively strong Lewis
acid is greatly beneficial to the efficient conversion of FF to GVL by
tandem transfer hydrogenation, alcoholysis and cyclization.
Reaction conditions: 0.05 mol/L FF, 20 mL 2-propanol, 0.192 g ZPS-1.0 and N2
at atmospheric conditions.
from alcohols, which can favor transfer hydrogenation of FF and IPL
[83]. As summarized in Table 4, secondary alcohols (e.g. isopropanol,
isobutanol) with lower reduction potential offered the higher FF con-
version and GVL selectivity versus to primary alcohols (e.g. ethanol,
n-propanol, n-butanol), owing to easier elimination of β-hydrides from
secondary alcohols [84]. The steric hindrance of alcoholic solvents
should also be taken into account because it has an adverse impact on
the formation of intermediate ethers (e.g. FE). As for secondary alcohols
in Table 4, isopropanol afforded a higher GVL selectivity (80.4 %) than
that of isobutanol (60.0 %) although isobutanol has a relatively lower
reduction potential (Table 4, entries 4 and 5). This is because the steric
hindrance of isobutanol (5.312 kcal/mol) is higher than that of iso-
propanol (4.116 kcal/mol), which suppressed the formation of inter-
mediate ethers. Therefore, alcohol with low reduction potential and
steric hindrance is a more effective solvent for the integrated production
of GVL from FF.
3.5. Effect of reaction parameters
The effects of reaction time and temperature on the catalytic per-
formance of ZPS-1.0 were studied. As shown in Table 5, an increase of
reaction time facilitated the consumption of FF to produce GVL. With the
prolongation of reaction time from 2 to 10 h at 150 ◦C, the FF conversion
and GVL selectivity gradually increased from 53.0 % and 10.0%–100.0%
and 65.1 %, respectively (Table 5, entries 1~3). Intermediate products
including FE and IPL were also detected in the range of 2~10 h. As the
reaction time was prolonged to 18 h, FF and intermediates were entirely
consumed and the highest GVL selectivity up to 80.0 % was achieved
(Table 5, entry 5). If the reaction time was further increased to 22 h, the
resulting GVL would be converted to undetected by-products. The effect
of reaction temperature on the FF conversion and product distribution
exhibited a comparable tendency as the reaction time. For example, the
FF conversion and the GVL selectivity gradually increased from 68.3 %
and 19.9%–100.0% and 80.0 in the temperature scope of 140~170 ◦C,
respectively (Table 5, entries 2 and 7~9). The above experimental
phenomena clearly suggested that the increment of reaction tempera-
ture or time in the proper range was beneficial to the improvement of FF
3.4. Effect of alcoholic solvents
The performance of the production of GVL from FF not only relies on
the selected catalyst but also on the used alcoholic solvents. The
reduction potential (ΔHof ) of alcohols plays a key role in the transfer
hydrogenation reactions within the process of GVL formation from FF.
Generally, low ΔHof means the more available dissociation of hydrogen
7

W. Li et al.
Molecular Catalysis 506 (2021) 111538
Fig. 7. Leaching test (a) and recycling test (b) of ZPS-1.0 in the conversion of FF to GVL. Reaction conditions: 0.05 mol/L FF, 20 mL 2-propanol, 0.192 g ZPS-1.0, 150
◦C, 18 h and N2 at atmospheric conditions.
regenerated ZPS-1.0 catalyst (Fig. 6b, Regeneration). Besides, almost the
Table 6
same XRD profiles for the fresh, used and regenerated catalysts were
BET surface for ZPS-1.0 of fresh, used 1 st, used 6th, and regeneration.
observed in Fig. S6. To sum up, ZPS-1.0 is a relatively stable and robust
Entry
ZPS-1.0
SBETa, m2/
g
Total acid sitesb,
mmol/g
C contentc, wt
%
catalyst for the direct transformation of GVL from FF in isopropanol.
1
2
3
4
Fresh
402
312
171
325
2.03
1.99
1.78
1.91
0.0
0.7
4.7
0.0
4. Conclusion
Used 1st
Used 6th
Regeneration
In this study, a series of SAPO-34 zeolite supported zirconium
phosphate (ZPS-X) catalysts were prepared for the one-pot trans-
formation of FF into GVL in isopropanol. The introduction of zirconium
phosphate brought about relatively strong L acid sites, and the ratio of L
to B acid sites could be modulated by adjustment of the Zr/P proportion
in ZPS-X catalysts. When the Zr/P ratio was adjusted to 1.0, the resulting
ZPS-1.0 with an appropriate ratio of L to B acid sites (3.25) exhibited
desirable catalytic activity, providing a GVL selectivity up to 80.0 % at a
full FF conversion.
a
BET surface area.
b
the amount of total acid sites was calculated by fitting deconvolution of
peaks in Fig. S8.
c
the carbon content was measured by elemental analysis.
conversion and GVL selectivity.
3.6. Leaching test and catalyst recirculation
CRediT authorship contribution statement
The stability and reusability performance of the catalyst were
determined by the leaching and recycling tests. As shown in Fig. 7a, after
taking out the catalyst at 10 h and then going on the reaction for 8 h, the
yield of GVL nearly remained at an identical level. Besides, almost little
Zr or P species (less than 11.0 ppm) from ZPS-1.0 was detected in the
filtrate by ICP-AES analysis. The above results implied that there was no
leaching of active components from the ZPS-1.0 catalyst in the process of
reaction.
Weile Li: Methodology, Validation, Formal analysis, Investigation,
Writing - original draft. Mengzhu Li: Validation, Investigation, Visual-
ization, Writing - review & editing. Huai Liu: Writing - review & editing.
Wenlong Jia: Writing - review & editing. Xin Yu: Investigation, Visu-
alization. Shuai Wang: Investigation. Xianhai Zeng: Conceptualiza-
tion, Supervision. Yong Sun: Conceptualization, Supervision. Junnan
Wei: Conceptualization, Writing - review & editing. Xing Tang:
Conceptualization, Writing - review & editing, Supervision. Lu Lin:
Conceptualization, Resources, Supervision.
Recycling tests of ZPS-1.0 for direct conversion of FF to GVL were
also carried out and the results were shown in Fig. 7b. When ZPS-1.0
catalyst was used in the second cycle, both FF conversion and GVL
selectivity nearly kept unchanged. Although the conversion of FF
remained constant (100 %) with the increasing cycle of ZPS-1.0 catalyst,
the selectivity of GVL gradually decreased after the 2th cycle. After the
ZPS-1.0 catalyst was sixth used, GVL selectivity decreased by about 20
%. The decrease of catalytic activity probably should be resulted from
the carbon deposits of the ZPS-1.0 catalyst during the reaction [85]. As
exhibited in Table 6, the carbon amount allocated to carbon deposition
increased from 0.0–4.7 wt% with the round of cycle, while the number
of acidic sites and BET surface area of the spent ZPS-1.0 catalyst
remarkably dropped from 2.03 mmol/g and 402 m2/g to 1.78 mmol/g
and 171 m2/g, respectively. The above results illustrated that the carbon
deposits covered the active sites and/or blocked the pores of ZPS-1.0
catalysts. To remove carbon deposits of the spent ZPS-1.0 catalyst, the
spent catalyst was calcined at 400 ◦C for 4 h. After the complete removal
of the carbon deposits on the spent ZPS-1.0 catalyst, the number of total
acidic sites and BET surface area of the regenerated ZPS-1.0 catalyst
recovered to 1.91 mmol/g and 325 m2/g, respectively (Table 6, entry 4).
As expected, the selectivity of GVL recovered to 75 % over the
Declaration of Competing Interest
The authors report no declarations of interest.
Acknowledgements
We are grateful for funding supported by the National Natural Sci-
ence Foundation of China (Grant Nos. 22078275; 21978246), the Key-
Area Research and Development Program of Guangdong Province
(Grant No. 2020B0101070001).
Appendix B. Supplementary data
Supplementary material related to this article can be found, in the
online version, at doi:https://doi.org/10.1016/j.mcat.2021.111538.
8

W. Li et al.
Molecular Catalysis 506 (2021) 111538
[30] S. Dutta, S. De, B. Saha, M.I. Alam, Advances in conversion of hemicellulosic
biomass to furfural and upgrading to biofuels, Catal. Sci. Technol. 2 (2012)
2025–2036.
References
[1] P. Bernstein, W.D. Montgomery, T.F. Rutherford, Global impacts of the Kyoto
agreement: results from the MS-MRT model, Resour. Energy Econ. 21 (1999)
375–413.
[31] X. Li, P. Jia, T. Wang, Furfural: a promising platform compound for sustainable
production of C4and C5Chemicals, ACS Catal. 6 (2016) 7621–7640.
[32] Z. Yu, X. Lu, C. Liu, Y. Han, N. Ji, Synthesis of γ-valerolactone from different
biomass-derived feedstocks: recent advances on reaction mechanisms and catalytic
systems, Renew. Sustain. Energy Rev. 112 (2019) 140–157.
[2] H. Zhang, H. Li, Y. Hu, K.T. Venkateswara Rao, C. Xu, S. Yang, Advances in
production of bio-based ester fuels with heterogeneous bifunctional catalysts,
Renew. Sustain. Energy Rev. 114 (2019) 109296–109321.
[33] H.P. Winoto, B.S. Ahn, J. Jae, Production of γ-valerolactone from furfural by a
single-step process using Sn-Al-beta zeolites: optimizing the catalyst acid properties
and process conditions, J. Ind. Eng. Chem. 40 (2016) 62–71.
[3] X. Hu, M. Gholizadeh, Biomass pyrolysis: a review of the process development and
challenges from initial researches up to the commercialisation stage, J. Energy
Chem. 39 (2019) 109–143.
[34] S. Zhu, Y. Xue, J. Guo, Y. Cen, J. Wang, W. Fan, Integrated conversion of
hemicellulose and furfural into gamma-valerolactone over Au/ZrO2 catalyst
combined with ZSM-5, ACS Catal. 6 (2016) 2035–2042.
[4] X. Chen, Y. Liu, J. Wu, Sustainable production of formic acid from biomass and
carbon dioxide, Mol. Catal. 483 (2020) 110716–110731.
[5] M.L. de Araújo, G.A. Correia, W.A. Carvalho, L.S. Shul’pina, Y.N. Kozlov, G.
B. Shul’pin, D. Mandelli, Transformation of biomass derivatives in aqueous
medium: oxidation of ethanol from sugarcane and acetol from biodiesel glycerol
catalyzed by Fe3+- H2O2, Mol. Catal. 500 (2021) 111307–111315.
[6] L. Hu, G. Zhao, W. Hao, X. Tang, Y. Sun, L. Lin, S. Liu, Catalytic conversion of
biomass-derived carbohydrates into fuels and chemicals via furanic aldehydes, RSC
Adv. 2 (2012) 11184–11206.
[35] L. Bui, H. Luo, W.R. Gunther, Y. Roman-Leshkov, Domino reaction catalyzed by
zeolites with Bronsted and Lewis acid sites for the production of gamma-
valerolactone from furfural, Angew. Chem. 52 (2013) 8022–8025.
[36] H.P. Winoto, Z.A. Fikri, J.-M. Ha, Y.-K. Park, H. Lee, D.J. Suh, J. Jae,
Heteropolyacid supported on Zr-Beta zeolite as an active catalyst for one-pot
transformation of furfural to γ-valerolactone, Appl. Catal. B Environ. 241 (2019)
588–597.
[7] X. Tang, X. Zeng, Z. Li, L. Hu, Y. Sun, S. Liu, T. Lei, L. Lin, Production of
γ-valerolactone from lignocellulosic biomass for sustainable fuels and chemicals
supply, Renew. Sustain. Energy Rev. 40 (2014) 608–620.
[37] S. Song, L. Di, G. Wu, W. Dai, N. Guan, L. Li, Meso-Zr-Al-beta zeolite as a robust
catalyst for cascade reactions in biomass valorization, Appl. Catal. B Environ. 205
(2017) 393–403.
[8] J.J. Bozell, L. Moens, D.C. Elliott, Y. Wang, G.G. Neuenscwander, S.W. Fitzpatrick,
R.J. Bilski, J.L. Jarnefeld, Production of levulinic acid and use as a platform
chemical for derived products, Resour. Conserv. Recycl. 28 (2000) 227–239.
[9] W. Deng, Q. Zhang, Y. Wang, Catalytic transformations of cellulose and its derived
carbohydrates into 5-hydroxymethylfurfural, levulinic acid, and lactic acid, Sci.
China Chem. 58 (2014) 29–46.
[38] A. Zebardasti, M.G. Dekamin, E. Doustkhah, M.H.N. Assadi, Carbamate-
isocyanurate-bridged periodic mesoporous organosilica for van der Waals CO2
capture, Inorg. Chem. 59 (2020) 11223–11227.
[39] E. Doustkhah, Y. Ide, Microporous layered silicates: old but new microporous
materials, New J. Chem. 44 (2020) 9957–9968.
[40] F. Hashemi, M. Taghizadeh, M.D. Rami, Polyoxometalate modified SAPO-34: a
highly stable and selective catalyst for methanol conversion to light olefins,
Microporous Mesoporous Mater. 295 (2020) 109970–109980.
[10] N. Chen, Z. Zhu, H. Ma, W. Liao, H. Lü, Catalytic upgrading of biomass-derived 5-
hydroxymethylfurfural to biofuel 2,5-dimethylfuran over beta zeolite supported
non-noble Co catalyst, Mol. Catal 486 (2020) 110882–110890.
[41] E. Doustkhah, H. Mohtasham, M. Farajzadeh, S. Rostamnia, Y. Wang,
H. Arandiyan, M.H.N. Assadi, Organosiloxane tunability in mesoporous
organosilica and punctuated Pd nanoparticles growth; theory and experiment,
Microporous Mesoporous Mater. 293 (2020) 109832–109839.
[11] W. Fang, H. Sixta, Advanced biorefinery based on the fractionation of biomass in
gamma-valerolactone and water, ChemSusChem 8 (2015) 73–76.
[12] G. Strappaveccia, E. Ismalaj, C. Petrucci, D. Lanari, A. Marrocchi, M. Drees,
A. Facchetti, L. Vaccaro, A biomass-derived safe medium to replace toxic dipolar
solvents and access cleaner Heck coupling reactions, Green Chem. 17 (2015)
365–372.
[42] E. Doustkhah, Y. Ide, Bursting exfoliation of a microporous layered silicate to
three-dimensionally meso–microporous nanosheets for improved molecular
recognition, ACS Appl. Nano Mater. 2 (2019) 7513–7520.
[13] J.C. Serrano-Ruiz, D. Wang, J.A. Dumesic, Catalytic upgrading of levulinic acid to
5-nonanone, Green Chem. 12 (2010) 574–577.
[43] R. Szostak, Molecular sieves: principles of synthesis and identification. Van
Nostrand Reinhold, New York, 1989, Clay Miner. 25 (1990), 244-244.
[44] Z. Zong, X. Feng, Y. Huang, Z. Song, R. Zhou, S.J. Zhou, M.A. Carreon, M. Yu, S. Li,
Highly permeable N2/CH4 separation SAPO-34 membranes synthesized by diluted
gels and increased crystallization temperature, Microporous Mesoporous Mater.
224 (2016) 36–42.
[14] D. Ren, X. Wan, F. Jin, Z. Song, Y. Liu, Z. Huo, Selective hydrogenation of
levulinate esters to 1,4-pentanediol using a ternary skeletal CuAlZn catalyst, Green
Chem. 18 (2016) 5999–6003.
[15] S. Raoufmoghaddam, M.T. Rood, F.K. Buijze, E. Drent, E. Bouwman, Catalytic
conversion of gamma-valerolactone to ε-caprolactam: towards nylon from
[45] J. Ding, P. Wang, S. Ji, H. Wang, D.J.L. Brett, R.J.E.A. Wang, Mesoporous nickel
selenide N-doped carbon as a robust electrocatalyst for overall water splitting,
Electrochim. Acta 300 (2019) 93–101.
renewable feedstock, ChemSusChem 7 (2014) 1984–1990.
[16] L.E. Manzer, Catalytic synthesis of α-methylene-γ-valerolactone: a biomass-derived
acrylic monomer, Appl. Catal. A Gen. 272 (2004) 249–256.
[17] J.Q. Bond, D.M. Alonso, D. Wang, R.M. West, J.A. Dumesic, Integrated catalytic
conversion of γ-valerolactone to liquid alkenes for transportation fuels, Science 327
(2010) 1110–1114.
[46] D.L. A, B.X. A, B.W. B, R.L. A, Activity and selectivity of methanol-to-olefin
conversion over Zr-modified H-SAPO-34/H-ZSM-5 zeolites - a theoretical study,
Fuel Process. Technol. 199 (2020) 106302–106313.
[47] E. Doustkhah, H. Mohtasham, M. Hasani, Y. Ide, S. Rostamnia, N. Tsunoji,
M. Hussein, N. Assadi, Merging periodic mesoporous organosilica (PMO) with
mesoporous aluminosilica (Al/Si-PMO): a catalyst for green oxidation, Mol. Catal.
482 (2020) 110676–110682.
[18] D.M. Alonso, J.Q. Bond, J.C. Serrano-Ruiz, J.A. Dumesic, Production of liquid
hydrocarbon transportation fuels by oligomerization of biomass-derived C9
alkenes, Green Chem. 12 (2010) 992–999.
[19] A. Osatiashtiani, A.F. Lee, K. Wilson, Recent advances in the production of
γ-valerolactone from biomass-derived feedstocks via heterogeneous catalytic
transfer hydrogenation, J. Chem. Technol. Biotechnol. 92 (2017) 1125–1135.
[20] L. Yan, Q. Yao, Y. Fu, Conversion of levulinic acid and alkyl levulinates into
biofuels and high-value chemicals, Green Chem. 19 (2017) 5527–5547.
[21] D.M. Alonso, S.G. Wettstein, J.A. Dumesic, Gamma-valerolactone, a sustainable
platform molecule derived from lignocellulosic biomass, Green Chem. 15 (2013)
584–595.
[48] G. Gliozzi, A. Innorta, A. Mancini, R. Bortolo, C. Perego, M. Ricci, F. Cavani, Zr/P/
O catalyst for the direct acid chemo-hydrolysis of non-pretreated microcrystalline
cellulose and softwood sawdust, Appl. Catal. B Environ. 145 (2014) 24–33.
[49] L. Hu, N. Li, X. Dai, Y. Guo, Y. Jiang, A. He, J. Xu, Highly efficient production of
2,5-dihydroxymethylfuran from biomass-derived 5-hydroxymethylfurfural over an
amorphous and mesoporous zirconium phosphonate catalyst, J. Energy Chem. 37
(2019) 82–92.
[50] F. Huang, J. Cao, L. Wang, X. Wang, F. Liu, Enhanced catalytic behavior for
methanol to lower olefins over SAPO-34 composited with ZrO2, Chem. Eng. J. 380
(2020) 122626–122636.
[22] C. Zhang, Z. Huo, D. Ren, Z. Song, Y. Liu, F. Jin, W. Zhou, Catalytic transfer
hydrogenation of levulinate ester into γ-valerolactone over ternary Cu/ZnO/Al2O3
catalyst, J. Energy Chem. 32 (2019) 189–197.
[51] P. Liu, J. Ren, Y. Sun, Influence of template on Si distribution of SAPO-11 and their
performance for n-paraffin isomerization, Microporous Mesoporous Mater. 114
(2008) 365–372.
[23] J. He, H. Li, Y. Xu, S. Yang, Dual acidic mesoporous KIT silicates enable one-pot
production of γ-valerolactone from biomass derivatives via cascade reactions,
Renew. Energy 146 (2020) 359–370.
[52] L. Wang, W. Li, G. Qi, D. Weng, Location and nature of Cu species in Cu/SAPO-34
for selective catalytic reduction of NO with NH3, J. Catal. 289 (2012) 21–29.
[53] S. Ren, G. Liu, X. Wu, X. Chen, M. Wu, G. Zeng, Z. Liu, Y. Sun, Enhanced MTO
performance over acid treated hierarchical SAPO-34, Chin. J. Catal 38 (2017)
123–130.
[24] P.J.C.S.R. Gallezot, Conversion of biomass to selected chemical products, Chem.
Soc. Rev. 41 (2012) 1538–1558.
[25] R. Mariscal, P. Mairelestorres, M. Ojeda, I. Sadaba, M.L. Granados, Furfural: a
renewable and versatile platform molecule for the synthesis of chemicals and fuels,
Energy Environ. Sci. 9 (2016) 1144–1189.
[54] Rahman, Pal Muttakin, Saha Shafiullah, A statistical approach to determine
optimal models for IUPAC-Classified adsorption isotherms, Energies 12 (2019)
4565–4598.
[26] B. Wang, C. Li, B. He, J. Qi, C. Liang, Highly stable and selective Ru/NiFe 2 O 4
catalysts for transfer hydrogenation of biomass-derived furfural to 2-methylfuran,
J. Energy Chem. 26 (2017) 799–807.
[55] M. Muttakin, S. Mitra, K. Thu, K. Ito, B.B. Saha, Theoretical framework to evaluate
minimum desorption temperature for IUPAC classified adsorption isotherms, Int. J.
Heat Mass Transf. 122 (2018) 795–805.
[27] G. Singh, L. Singh, J. Gahtori, R.K. Gupta, C. Samanta, R. Bal, A. Bordoloi, Catalytic
hydrogenation of furfural to furfuryl alcohol over chromium-free catalyst:
enhanced selectivity in the presence of solvent, Mol. Catal. 500 (2021)
111339–111351.
[56] K. Barbera, P. Lanzafame, A. Pistone, S. Millesi, G. Malandrino, A. Gulino,
S. Perathoner, G. Centi, The role of oxide location in HMF etherification with
ethanol over sulfated ZrO2 supported on SBA-15, J. Catal. 323 (2015) 19–32.
[57] D. Wang, L. Zhang, K. Kamasamudram, W.S. Epling, In Situ-DRIFTS study of
selective catalytic reduction of NOx by NH3 over Cu-Exchanged SAPO-34, ACS
Catal. 3 (2013) 871–881.
[28] C. Fang, Y. Liu, W. Wu, H. Li, Z. Wang, W. Zhao, T. Yang, S. Yang, One pot cascade
conversion of bio-based furfural to levulinic acid with Cu-doped niobium
phosphate catalysts, Waste Biomass Valoriz. 10 (2017) 1141–1150.
[29] Q. Liu, Q. Liu, X. Hu, Selective conversion of furfural into value-added chemical
commodity in successive fixed-bed reactors, Catal. Commun. 135 (2020)
105836–105840.
9

W. Li et al.
Molecular Catalysis 506 (2021) 111538
´
[58] D. Wang, L. Zhang, J. Li, K. Kamasamudram, W.S. Epling, NH3-SCR over Cu/SAPO-
34 – zeolite acidity and Cu structure changes as a function of Cu loading, Catal.
Today 231 (2014) 64–74.
[73] B. Pawelec, S. Murcia-Mascaros, J.L.G. Fierro, Surface and structural features of Pt/
Pd-Loaded mesoporous silica-delaminated zirconium phosphate systems, Langmuir
18 (2002) 7953–7963.
[59] J. Wang, D. Fan, T. Yu, J. Wang, T. Hao, X. Hu, M. Shen, W. Li, Improvement of
low-temperature hydrothermal stability of Cu/SAPO-34 catalysts by Cu 2+ species,
J. Catal. 322 (2015) 84–90.
[74] X. Tang, J. Wei, N. Ding, Y. Sun, X. Zeng, L. Hu, S. Liu, T. Lei, L.J.R. Lin, S.
E. Reviews, Chemoselective hydrogenation of biomass derived 5-hydroxymethyl-
furfural to diols: key intermediates for sustainable chemicals, Mater. Fuels 77
(2017) 287–296.
[60] L. Wang, W. Li, S.J. Schmieg, D. Weng, Role of Brønsted acidity in NH3 selective
catalytic reduction reaction on Cu/SAPO-34 catalysts, J. Catal. 324 (2015) 98–106.
[61] A. Izadbakhsh, F. Farhadi, F. Khorasheh, S. Sahebdelfar, M. Asadi, Y.Z. Feng, Effect
of SAPO-34’s composition on its physico-chemical properties and deactivation in
MTO process, Appl. Catal. A Gen. 364 (2009) 48–56.
[75] W. Li, Z. Cai, H. Li, Y. Shen, Y. Zhu, H. Li, X. Zhang, F. Wang, Hf-based metal
organic frameworks as bifunctional catalysts for the one-pot conversion of furfural
to γ-valerolactone, Mol. Catal 472 (2019) 17–26.
[76] B. Srinivasa Rao, P. Krishna Kumari, P. Koley, J. Tardio, N. Lingaiah, One pot
selective conversion of furfural to γ-valerolactone over zirconia containing
heteropoly tungstate supported on β-zeolite catalyst, Mol. Catal. 466 (2019) 52–59.
[77] M. Ma, H. Liu, J. Cao, P. Hou, J. Huang, X. Xu, H. Yue, G. Tian, S. Feng, A highly
efficient Cu/AlOOH catalyst obtained by in situ reduction: catalytic transfer
hydrogenation of ML into γ-GVL, Mol. Catal. 467 (2019) 52–60.
[62] J. Wang, T. Yu, X. Wang, G. Qi, J. Xue, M. Shen, W. Li, The influence of silicon on
the catalytic properties of Cu/SAPO-34 for NOx reduction by ammonia-SCR, Appl.
Catal. B Environ. 127 (2012) 137–147.
[63] V.V. Ordomsky, J.V. Der Schaaf, J.C.J. Schouten, T.A. Nijhuis, Fructose
dehydration to 5-hydroxymethylfurfural over solid acid catalysts in a biphasic
system, ChemSusChem 5 (2012) 1812–1819.
´
´
[78] V. Sanchez, P. Salagre, M.D. Gonzalez, J. Llorca, Y. Cesteros, Effect of the
formation of NiCu alloy and use of biomass-derived furfural on the catalytic
hydrogenation of furfural to THFA, Mol. Catal. 490 (2020) 110956–110965.
[79] K.T. Tomoo Mizugaki, Zen Maeno, Takato Mitsudome, Koichiro Jitsukawa,
Kiyotomi Kaneda, One-Pot transformation of levulinic acid to 2-methyltetrahy-
drofuran catalyzed by Pt–Mo/H-β in Water, ACS Sustain. Chem. Eng. 4 (2016)
682–685.
[64] F. Li, Z. Cai, Y. Li, S. Liu, H. Lou, J. Long, X. Li, Catalytic transfer hydrogenation of
butyl levulinate to γ-valerolactone over zirconium phosphates with adjustable
Lewis and Brønsted acid sites, Appl. Catal. B Environ. 214 (2017) 67–77.
[65] V.V. Ordomsky, V.L. Sushkevich, J.C. Schouten, J.V. Der Schaaf, T.A. Nijhuis,
Glucose dehydration to 5-hydroxymethylfurfural over phosphate catalysts, J. Catal.
300 (2013) 37–46.
´
[66] J. Wei, T. Wang, H. Liu, M. Li, X. Tang, Y. Sun, X. Zeng, L. Hu, T. Lei, L. Lin, Highly
efficient reductive etherification of 5-Hydroxymethylfurfural to 2,5-Bis
(Alkoxymethyl)furans as biodiesel components over Zr-SBA catalyst, Energy
Technol. 7 (2019) 1801071–1801081.
[80] H.Y. Luo, D.F. Consoli, W.R. Gunther, Y. Roman-Leshkov, Investigation of the
reaction kinetics of isolated Lewis acid sites in Beta zeolites for the
Meerwein–Ponndorf–Verley reduction of methyl levulinate to γ-valerolactone,
J. Catal. 320 (2014) 198–207.
[67] J. Song, L. Wu, B. Zhou, H. Zhou, H. Fan, Y. Yang, Q. Meng, B. Han, A new porous
Zr-containing catalyst with a phenate group: an efficient catalyst for the catalytic
transfer hydrogenation of ethyl levulinate to γ-valerolactone, Green Chem. 17
(2015) 1626–1632.
[81] S. Fang, Z. Cui, Y. Zhu, C. Wang, J. Bai, X. Zhang, Y. Xu, Q. Liu, L. Chen, Q. Zhang,
L. Ma, In situ synthesis of biomass-derived Ni/C catalyst by self-reduction for the
hydrogenation of levulinic acid to γ-valerolactone, J. Energy Chem. 37 (2019)
204–214.
[68] J. Song, B. Zhou, H. Zhou, L. Wu, Q. Meng, Z. Liu, B. Han, Porous zirconium–phytic
acid hybrid: a highly efficient catalyst for Meerwein–Ponndorf–Verley reductions,
Angew. Chem. 54 (2015) 9399–9403.
[82] R. Palkovits, Pentenoic acid pathways for cellulosic biofuels, Angew. Chem. 49
(2010) 4336–4338.
[83] J.C.V.D. Waal, P.J. Kunkeler, K. Tan, H.V. Bekkum, Zeolite titanium beta : a
selective catalyst for the gas-phase Meerwein–Ponndorf–Verley, and oppenauer
reactions, J. Catal. 173 (1998) 74–83.
[69] H.J.M. Bosman, A.P. Pijpers, A.W.M.A. Jaspers, An X-Ray photoelectron
spectroscopy study of the acidity of SiO 2–ZrO 2Mixed oxides, J. Catal. 161 (1996)
551–559.
[84] W.C. Yun, M.T. Yang, K.A. Lin, Water-born zirconium-based metal organic
frameworks as green and effective catalysts for catalytic transfer hydrogenation of
levulinic acid to gamma-valerolactone: critical roles of modulators, J. Colloid
Interface Sci. 543 (2019) 52–63.
[70] H. Li, Z. Fang, J. He, S. Yang, Orderly layered Zr-benzylphosphonate nanohybrids
for efficient acid–base-mediated bifunctional/cascade catalysis, ChemSusChem 10
(2016) 681–686.
[71] Z.-Y. Yuan, T.-Z. Ren, A. Azioune, J.-J. Pireaux, B.-L. Su, Marvelous self-assembly
of hierarchically nanostructured porous zirconium phosphate solid acids with high
thermal stability, Catal. Today 105 (2005) 647–654.
[85] Z. Hou, J. Gao, J. Guo, D. Liang, H. Lou, X. Zheng, Deactivation of Ni catalysts
during methane autothermal reforming with CO2 and O2 in a fluidized-bed
reactor, J. Catal. 250 (2007) 331–341.
[72] V. Patil, K. Agrawal, V. Barhate, S. Patil, A. Mahajan, XPS study of homemade
plasma enhanced atomic layer deposited La2O3/ZrO2 bilayer thin films, Semicon.
Sci. Technol. 34 (2019) 034004–034008.
10