Hydrothermal synthesis of boron-free Zr-MWW and Sn-MWW zeolites as robust Lewis acid catalysts

Article abstract of DOI:10.1039/d0cc00483a

An innovative strategy based on dual structure-directing agent-facilitated crystallization was proposed to hydrothermally synthesize boron-free Zr-MWW and Sn-MWW metallosilicates that bear great structural diversity for potential pore engineering. The metallosilicates show distinctive features in Lewis acid-catalyzed reactions as efficient heterogeneous solid catalysts.

Full text of DOI:10.1039/d0cc00483a

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Conformational control of nonplanar free base porphyrins:
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Hydrothermal synthesis of boron-free Zr-MWW and Sn-MWW
zeolites as robust Lewis acid catalysts†
Zhiguo Zhu,a Yejun Guan,b Haikuo Ma,a Hao Xu,b* Jin-gang Jiang,b Hongying Lüa and Peng Wub*
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
www.rsc.org/
An innovative strategy via dual structure-directing agents- simple calcination.11 Meanwhile, the layered characteristics of
cooperated crystallization was proposed to hydrothermally as-synthesized MWW precursors endow them great
a
synthesize boron-free Zr-MWW and Sn-MWW metallosilicates, structural diversity like phase delamination and interlayer
bearing a great structural diversity for potential pore-engineering. intercalation.12,13 The large external surface area and side
They revealed distinctive features in Lewis acid catalyzed pocket on the crystal surface of MWW zeolite facilitate bulky
reactions as effcient heterogeneous solid catalysts.
substrates to contact active sites and alleviate diffusion
restrictions.14 Therefore, MWW-type metallosilicates are
fascinating materials in the perspective of catalytic
applications and structure diversity.
Stannosilicates and zirconosilicates such as Sn-Beta,1,2 Sn-MFI,3
Sn-MEL,4 Zr-Beta,5 and Zr-BEC6, possessing isolated metal ions
isomorphously substituted in the zeolite framework, are
gaining more and more attentions recently due to their unique
catalytic features (activation of carbonyl-containing molecules)
in the field of biomass conversion.7 Among them, Sn-Beta and
Zr-Beta have become superstar catalysts, whose new synthesis
methods and innovative applications emerged in endlessly.8
Although the hydrophobicity of Sn-Beta and Zr-Beta could be
significantly enhanced by fluoride-mediated preparation,1 the
BEA* intergrowth structure consisting of polymorphs A and B
induces a congenitally deficient issue of relatively high
hydrophilicity.9 Additionally, bulky organics, which usually
appear in the process of biomass conversion, probably can not
access to active sites within zeolite framework due to the
limited window size of BEA* zeolite (6.6 × 6.7 Å) and
encounter diffusion limitations.10
MWW topology structure encompasses two independent
channel systems of 12-membered ring (12MR) supercages (7 ×
7 × 18 Å) linked through 10MR orifice and 2-dimensional (2D)
10MR sinusoidal channels, whose crystal surface is terminated
with 12MR side pockets.11,12 The 3D MWW framework
structure is usually generated from corresponding
hydrothermally synthesized 2D lamellar precursors after
Scheme 1 Schematic diagram of structural transformation for Sn-MWW or Zr-
MWW during post-treatment processes.
A series of methods have been proposed to realize the
success substitution of Sn or Zr ions into MWW framework.15–
19 Our group firstly reported the hydrothermal synthesis of Sn-
MWW and Zr-MWW zeolite using piperidine and boric acid as
structure-directing and crystallization-supporting agent,
respectively, in which alkali metal ions were necessary.15,16
Hensen et al. prepared boron-free Sn-MWW via a reversible
structure transformation, which showed excellent catalytic
performances in the conversion of trioses to lactic acid.17
Delaminated and pillared Sn-MWW and Zr-MWW zeolites
were also applied in Baeyer-Villiger oxidation as effective
a Green Chemistry Centre, College of Chemistry and Chemical Engineering, Yantai
University, 30 Qingquan Road, Yantai 264005, Shandong, China
b Shanghai Key Laboratory of Green Chemistry and Chemical Process, School of
Chemistry and Molecular Engineering, East China Normal University, North
Zhongshan Rd. 3663, Shanghai 200062, China
E-mail: pwu@chem.ecnu.edu.cn (P. Wu), hxu@chem.ecnu.edu.cn (H. Xu)
†Electronic Supplementary Information (ESI) available: Details of experimental
procedures and material characterization. See DOI: 10.1039/x0xx00000x
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Lewis acid catalysts.18,19 Nonetheless, these methods require amorphous phase, were observed for Zr-MWW-50P and Sn-
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DOI: 10.1039/D0CC00483A
the co-existence of boron, multi-steps, and/or need dangerous MWW-50P with high metal contents.
operations. Thus, with the purpose to overcome the existing
Besides the metal content, the coordination state of metals
disadvantages, it is worthwhile to explore a more facile route within zeolite matrix is even more important for the catalytic
like boron-free direct synthesis to develop Sn-MWW and Zr- behaviors of metallosilicates.4,5,11,21 Thus, UV-vis spectra were
MWW zeolites as efficient heterogeneous catalysts.
adopted to investigate the coordinate state of Zr and Sn
In this communication, boron-free Sn-MWW and Zr-MWW species within MWW zeolite. As demonstrated in Fig. 2Aa, the
zeolites were hydrothermally synthesized using co-structure- precursor Zr-MWW-100P possessed a band at approximate
directing agents of N,N,N-trimethyl-1-adamantammonium 230 nm, ascribed to extra-framework Zr species.22 The broad
hydroxide (TMAdaOH) and hexamethyleneimine (HMI). An band in the range of 230–300 nm was obviously noticed when
acid treatment was necessary to remove the extra-framework Zr-MWW-100P sample was directly calcined at 823 K (Fig. 2Ad).
metal species as graphically shown in Scheme 1. Eventually, This indicated that Zr species mainly existed in the extra-
these two materials were evaluated in the Meerwein– framework positions after direct calcination of precursor. Acid
Pondorf–Verley (MPV) of cyclohexanone and Baeyer-Villiger treatment followed by calcination was an effective method to
(B-V) oxidation of 2-adamantanone.
remove extra-framework Ti species for Ti-MWW zeolite.11
The siliceous Si-MWW (ITQ-1) zeolite was readily crystallized Consequently, this approach was also employed to change the
in the absence of alkali metal ions such as K+.20 Unfortunately, coordination state of Sn and Zr species in the present study.
the crystallization was stagnated once the Zr4+ or Sn4+ species Fascinatingly, the majority of extra-framework Zr species over
were introduced into synthesis gels, yielding only amorphous Zr-MWW-100P were eliminated after HNO3 treatment.
phase (Fig. S1, ESI†). Surprisingly, Sn-MWW-100P and Zr- Meanwhile an intensive band at around 207 nm, assigned to
MWW-100P were smoothly obtained with the addition of K+ or the charge transfer from O2- to tetrahedrally coordinated Zr4+
Na+ (Fig. 1 and Fig. S2, ESI†), indicating that alkali metal species in the zeolite framework,22,23 was clearly found for Zr-MWW-
were necessary mineralizers for the crystallization of MWW- 100-A and Zr-MWW-100-AC (Fig. 2A, b and c). As shown in Fig.
type metallosilicates. Besides, the organics of TMAda+ and HMI S6 (ESI†), Zr species in Zr-MWW-150-AC also mainly existed in
co-existed within as-synthesized Zr-MWW zeolite and their the four-fold coordinated state, which was further confirmed
structures were preserved well as shown in 13C MAS NMR by Zr 3d XPS (Fig. S7A, ESI†). This acid-calcination treatment is
spectrum (Fig. S3b, ESI†).
also effective in removing extra-framework Sn species in Sn-
MWW zeolites (Figs. 2B, S6B, and S7B). Consistently, the
Si/metal molar ratio was increased in the acid-calcination
treatment for the selective removal of extra-framework Zr or
Sn species (Table S1, ESI†).
A
B
[001]
[100]
[001]
[100]
[101]
[002] [102]
[101]
[002] [102]
d
c
d
c
A
B
207
210
b
a
a
d
b
a
a
d
5
10 15 20 25 30 35
5
10 15 20 25 30 35
c
2 Theta 
2 Theta 
c
b
Fig. 1 XRD patterns of (A) Zr-MWW-100 and (B) Sn-MWW-100 in as-synthesized form
(a), as a after acid treatment (b), further calcination (c), and as a calcined directly (d).
b
200 250 300 350 400 450 500
200 250 300 350 400 450 500
Wavelength nm
Wavelength nm
The metal contents within metallosilicates were closely
related to their catalytic performances, meanwhile the hetero
metal ions in particular with a large radius generally tended to
retard the zeolite crystallization.11,15,21 Therefore, the
crystallization was attempted by varying Si/metal molar ratio
from 150 to 30 (Fig. S4, ESI†). For both Zr-MWW and Sn-MWW
zeolites, the characteristic diffraction peaks at 2θ = 3.3, 6.5,
7.2, 7.9, 9.7, 19.4, 22.7, and 26.2o, attributed to MWW
topology structure,11 were clearly observed when the metal
contents were low (Si/metal = 150 and 100). Further increasing
metal contents (Si/metal = 50 and 30), the intensities of
corresponding diffractions sharply decreased, due to the
retarding effect of Zr4+ or Sn4+ for crystallization. Besides, Sn-
MWW-100P and Zr-MWW-100P possessed typical plate-like
morphology (Fig. S5, ESI†). Nonetheless, numerous sponge-like
substances adhering to MWW crystals, probably assigned to
Fig. 2 UV-vis spectra of different Zr-MWW and Sn-MWW samples. (A) Zr-MWW-100P
(a), Zr-MWW-100-A (b), Zr-MWW-100-AC (c), and Zr-MWW-100-C (d); (B) Sn-MWW-
100P (a), Sn-MWW-100-A (b), Sn-MWW-100-AC (c), and Sn-MWW-100-C (d).
Furthermore, FT-IR spectra were also employed to study the
metal coordination state. Zr-O bond in the Zr-O tetrahedral
unit demonstrated 846 cm−1 vibration band,24 unfortunately
which was overlapped with the Si-O signal from zeolite
framework. On the other hand, some metal ions locating in the
zeolite framework such as titanosilicates could generate Si-O-
M (metal) stretching vibration at about 960 cm−1 in the
framework region of FT-IR spectra.11 As shown in Fig. S8 (ESI†),
both Zr-MWW-100-AC and Sn-MWW-100-AC samples showed
weak shoulder peak centered at approximate 960 cm−1, which
was measured at room temperature. Upon heating at 823 K
under evacuation condition, this signal completely
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disappeared for Zr-MWW-100-AC, while a blue shift from 960 1449, 1490, and 1609 cm−1.21 With desorption VtieewmAprtieclreaOtnulirnee
to 970 cm−1 took place over Sn-MWW-100-AC. Condensation increasing, the hydrogen-bonded pyriDdOinI:e10.a10n3d9/DL0eCwCis004a8c3idA
of hydroxyl groups at 823 K likely contributed to the related bands gradually decreased. Nonetheless, the decrease
disappearance of 960 cm−1 signal band for Zr-MWW zeolite of the bands due to hydrogen-bonded pyridine was more
derived from the isolated internal silanol groups.25 Therefore, obvious than those of pyridine absorbed on Lewis acid sites,
960 cm−1 band in the FT-IR spectra could not be used as an indicative of the weak hydrogen bond strength. Very similar
evidence to determine whether Zr ions were incorporated into results were also observed on Sn-MWW (Fig. 3B). The Lewis
MWW zeolite framework or not. With respect to Sn-MWW acid strength was quantitatively estimated from the ratio of
zeolite, conclusion could be made that 970 cm−1 peak in FT-IR the 1450 cm−1 band intensity measured at desorption
spectra measured under evacuation was resulted from the temperature of 473 and 373 K.27 The ratio for Sn-MWW-100-
stretching vibration of Si-O-Sn bond, which indicated that Sn AC (0.58) was larger than that for Zr-MWW-100-AC (0.35),
ions were tetrahedrally coordinated in MWW zeolite.
implying the stronger Lewis acidity of Sn-MWW zeolite. The
Meanwhile, the structure transformation during the acid– density of the Lewis acid sites in the catalyst was determined
calcination treatment was also traced by the XRD technique. from the integral intensity of characteristic band at 1451 cm−1
As shown in Fig. 1, two peaks at 3.3 and 6.5o, corresponding to with the desorption temperature of 473 K.28 Sn-MWW-100-AC
[001] and [002] planes, respectively,12 completely disappeared exhibited higher Lewis acid density (36 μmol g−1) in
after direct calcination for Sn-MWW-100P due to the comparison with Zr-MWW-100-AC (23 μmol g−1). Thus, both
formation of 3D MWW structure derived from the the strength and density of Lewis acidity in Sn-MWW-100-AC
condensation of interlayer hydroxyl groups in 2D lamellar was superior to those in Zr-MWW-100-AC.
precursor. The [001] and [002] diffraction peaks were also
A
B
hardly observed for acid-treated Zr-MWW-100P-A (Fig. 1Ab).
This result suggested that the organics in the interlayer space
were mostly dislodged under the harsh acid treatment
conditions, in good consistent with the phenomena of Ti-
MWW zeolite reported previously.11 TG analysis (Fig. S9, ESI†)
proved partial elimination of organics occluded in zeolite via
acid treatment. In combination with CN elemental analysis
(Table S2, ESI†), it was speculated that the removed organics
were primarily TMAda+ locating in the interlayer region.
Through further calcination to remove residual organics
occluded in zeolite, the corresponding peak intensities slightly
decreased for Zr-MWW-100P-AC sample (Fig. 1Ac). For Sn-
MWW zeolite, it should be highlighted that [101] and [102]
diffraction peaks merged to form a broad and weak peak for
Sn-MWW-100-A, Sn-MWW-100-AC, and even direct calcined
Sn-MWW-100-C. This result implied that insertion of Sn with
large ions radius into MWW framework affected the
crystallographic structure of flexible MWW framework,
possibly generating MCM-56 or SSZ-70 analogues,15,26 which
was different from boron-containing Sn-B-MWW with typical
3D MWW topology structure (Fig. S10). Additionally, the
micropore volume and specific surface area for Zr-MWW-AC
and Sn-MWW-AC (Si/metal = 100 or 150) were approximate
0.14 cm3 g−1 and 495 m2 g−1 (Table S1, ESI†), respectively,
indicative of a high crystallinity. These results suggested that
boron-free Sn-MWW and Zr-MWW zeolites with tetrahedral
coordination state were successfully synthesized using dual
OSDA with the existence of K+ or Na+ when the Si/metal molar
ratio was ≥ 100.
1451
1445
1611
1596
1609
1594
1449
1490
1490
1444
a
b
c
a
b
c
d
e
d
e
1650 1600 1550 1500 1450 1400 1650 1600 1550 1500 1450 1400
Wavenumber cm-1
Wavenumber cm-1


Fig. 3 FT-IR spectra of (A) Zr-MWW-100-AC and (B) Sn-MWW-100-AC after pyridine
adsorption at 298 K for 1 h and desorption at 323 K (a), 373 K (b), 423 K (c), 473 K (d),
and 773 K (e) for 1 h, respectively.
MPV hydrogen transfer reaction and B-V oxidation were
used as model reactions to evaluate the catalytic
performances of Zr-MWW and Sn-MWW as heterogeneous
Lewis catalysts. MPV reaction of cyclohexanone was
performed using 2-propanol as both hydrogen resource and
solvent at 373 K. As shown in Table S3 (ESI†), when siliceous Si-
MWW, Zr-impregnated ZrO2/Si-MWW, and Sn-impregnated
SnO2/Si-MWW were utilized as catalysts, respectively, this
reaction did not proceed (Nos. 1−3). In contrast, a significant
high conversion was observed for Sn-MWW or Zr-MWW
zeolite, unravelling that the Lewis acidity derived from isolated
Zr or Sn sites within MWW framework was effective in
catalyzing MPV reaction. Additionally, the selectivity of
product cyclohexanol reached ~99 %. The catalytic
performance of boron-free Zr-MWW-100-AC (conversion, 96.3
%; selectivity, 99.0 %; TOF, 10.7 h−1) and Sn-MWW-100-AC
(conversion, 81.8 %; selectivity, 98.6 %; TOF, 9.3 h−1) zeolites
were superior to those of boron-containing Zr-B-MWW
(conversion, 89.3 %; selectivity, 96.2 %; TOF, 9.6 h−1) and Sn-B-
MWW (conversion, 72.5 %; selectivity, 91.3 %; TOF, 7.6 h−1)
zeolites under comparable Zr or Sn contents. The inferior
catalytic performance of boron-containing Zr-B-MWW and Sn-
B-MWW was probably ascribed to the weak acidity derived
from the boron species in zeolite framework.29 Zr-MWW-100-
Lewis acidity, as a factor of great concern for Lewis acid-
catalyzed reactions, generally stems from the isolated metal
ions in metallosilicates.2,21 Thus, the FT-IR spectra of pyridine
adsorbed Zr-MWW and Sn-MWW zeolites were measured to
analyze the Lewis acidity (Fig. 3). The bands at 1444 and 1594
cm−1, attributed to hydrogen-bonded pyridine,5 were observed
for Zr-MWW-100-AC at the low desorption temperature of 323
K. Meanwhile, it also revealed Lewis acid related bands at
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AC catalyst exhibited better performance (conversion, 96.3 %;
TOF, 10.7 h−1) than Zr-MWW-150-AC (conversion, 61.1 %; TOF,
9.8 h−1), resulting from the higher isolated Zr content. The
time-dependent catalytic performances for Zr-MWW-100-AC
and Sn-MWW-100-AC were also shown in Fig. 4. With reaction
time prolonging, the cyclohexanone conversion increased. The
catalytic activity of Zr-MWW was superior to that of Sn-MWW
with comparable metal content. At the reaction time of 8 h,
the cyclohexanone conversion over Zr-MWW-100-AC was 96.3
% with a TOF value of 10.7 h−1, higher than that over Sn-
MWW-100-AC with the conversion of 81.8 % and TOF value of
9.3 h−1. In addition, when the catalysts were extended to other
metal-containing MWW zeolites such as Al-MWW and Ti-
MWW, the catalytic results were unsatisfactory, further
proving the superiority of Zr-MWW in processing of MPV
reaction. In contrast, Sn-MWW zeolites showed higher
catalytic activity than Zr-MWW zeolites in B-V oxidation of 2-
adamantanone with similar metal content (Table S4, ESI†).
These different observations from catalytic performances over
Sn-MWW and Zr-MWW in MPV and B-V reactions were likely
to be contributed by their discrepant Lewis acidity (density and
strength, evidenced in Fig. S11).
Notes and references
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DOI: 10.1039/D0CC00483A
1
2
3
4
5
6
7
8
9
A. Corma, L. T. Nemeth, M. Renz and S. Valencia, Nature,
2001, 412, 423.
Z. Zhu, H. Xu, J. Jiang, H. Wu and P. Wu, Chem. Commun.,
2017, 53, 12516.
H. Y. Luo, L. Bui, W. R. Gunther, E. Min and Y. Román-
Leshkov, ACS Catal., 2012, 2, 2695.
N. K. Mal, V. Ramaswamy, S. Ganapathy and A. V.
Ramaswamy, Appl. Catal. A: Gen., 1995, 125, 233.
L. Bui, H. Luo, W. R. Gunther and Y. Román-Leshkov, Angew.
Chem. Int. Ed., 2013, 52, 8022.
P. A. Kots, V. L. Sushkevich, O. A. Tyablikov and I. I. Ivanova,
Micropor. Mesopor. Mater., 2017, 243, 186.
P. Y. Dapsens, C. Mondelli and J. Pérez-Ramírez, Chem. Soc.
Rev., 2015, 44, 7025.
Q. Meng, J. Liu, G. Xiong, X. Li, L. Liu and H. Guo, Micropor.
Mesopor. Mater., 2019, 287, 85.
Á. Cantín, A. Corma, M. J. Díaz-Cabañas, J. L. Jordá, M.
Moliner and F. Rey, Angew. Chem. Int. Ed., 2006, 45, 8013.
10 Z. Zhu, H. Xu, J. Jiang, X. Liu, J. Ding and P. Wu, Appl. Catal. A:
Gen., 2016, 519, 155.
11 P. Wu, T. Tatsumi, T. Komatsu and T. Yashima, J. Phys. Chem.
B, 2001, 105, 2897.
12 P. Wu, J. Ruan, L. Wang, L. Wu, Y. Wang, Y. Liu, W. Fan, M.
He, O. Terasaki and T. Tatsymi, J. Am. Chem. Soc., 2008, 130,
8178.
13 J. Přech, Catal. Rev., 2018, 60, 71.
14 P. Wu, T. Tatsumi, T. Komatsu and T. Yashima, J. Catal., 2001,
202, 245.
15 G. Liu, J. Jiang, B. Yang, X. Fang, H. Xu, H. Peng, L. Xu, Y. Liu
and P. Wu, Micropor. Mesopor. Mater., 2013, 165, 210.
16 A. Lv, Y. Liu, N. Liu, H. Wu, X. Li, M. He and P. Wu, Chem. Lett.,
2008, 37, 156.
17 Q. Guo, F. Fan, E. A. Pidko, W. N. P. van der Graaff, Z. Feng, C.
Li and E. J. M. Hensen, ChemSusChem, 2013, 6, 1352.
18 X. Ouyang, S. Hwang, D. Xie, T. Rea, S. I. Zones and A. Katz,
ACS Catal., 2015, 5, 3108.
A
B
b
b
100
80
60
40
20
0
100
80
60
40
20
0
a
a
0
2
4
6
8
10
0
2
4
6
8
10
Time (h)
Time (h)
Fig. 4 Time-dependent cyclohexanone conversion (a) and cyclohexanol selectivity (b)
over (A) Zr-MWW-100-AC and (B) Sn-MWW-100-AC catalysts. Reaction conditions: Cat.,
75 mg; cyclohexanone, 1 mmol; 2-propanol, 60 mmol; temp., 373 K.
19 L. Ren, Q. Guo, M. Orazov, D. Xu, D. Politi, P. Kumar, S. M.
Alhassan, K. A. Mkhoyan, D. Sidiras, M. E. Davis and M.
Tsapatsis, ChemCatChem, 2016, 8, 1274.
20 M. A. Camblor, A. Corma, M. Díaz-Cabañas and C.
Baerlocher, J. Phys. Chem. B, 1998, 102, 44.
21 Z. Zhu, H. Xu, J. Jiang, Y. Guan and P. Wu, J. Catal., 2017, 352,
1.
22 M. S. Morey, G. D. Stucky, S. Schwarz and M. Fröba, J. Phys.
Chem. B, 1999, 103, 2037.
23 K. Chaudhari, R. Bal, T. Kr. Das, A. Chandwadkar, D. Srinivas
and S. Sivasanker, J. Phys. Chem. B, 2000, 104, 11066.
24 F. Gonzalez-Vilchez and W. P. Griffith, J. Chem. Soc., Dalton
Trans., 1972, 1416.
25 T. D. Courtney, C. Chang, R. J. Gorte, R. F. Lobo, W. Fan and
V. Nikolakis, Micro. Mesopor. Mater., 2015, 210, 69.
26 W. J. Roth, P. Nachtigall, R. E. Morris and J. Čejka, Chem.
Rev., 2014, 114, 4807.
In conclusion, boron-free Zr-MWW and Sn-MWW zeolites
were hydrothermally synthesized via dual structure-directing
agent strategy, avoiding multi steps. Acid treatment prior to
calcination was an effective method to selectively remove the
extra-framework metal species. The different Lewis acid
strength of Zr-MWW and Sn-MWW contributed to discrepant
catalytic performances in MPV and B-V oxidation reactions.
The 2D lamellar structure of as-synthesized precursor for Zr-
MWW and Sn-MWW endows the significant potential of
structural diversity, whose crystal engineering in terms of
structural modification is promising and under investigation in
our laboratory.
27 W. N. P. van der Graaff, G. Li, B. Mezari, E. A. Pidko and E. J.
M. Hensen, ChemCatChem, 2015, 7, 1152.
28 C. A. Emeis, J. Catal., 1993, 141, 347.
29 P. Wu and T. Tatsumi, Chem. Commun., 2002, 1026.
A
The authors gratefully acknowledge the financial supports
from National Natural Science Foundation of China (Grant Nos.
21872052, 21533002 and 21972044), China Ministry of Science
and Technology (2016YFA0202804).
Conflicts of interest
There are no conflicts to declare.
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Boron-free Zr-MWW and Sn-MWW metallosilicates were successfully synthesized via
dual structure-directing agents-cooperated crystallization, which demonstrated unique
catalytic behaviors in Meerwein–Pondorf–Verley and Baeyer-Villiger oxidation
reactions.