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Hydrothermal synthesis of single-crystalline
mesoporous beta zeolite assisted by N-methyl-2-
pyrrolidone†
Cite this: RSC Adv., 2014, 4, 39297
Received 19th June 2014
Accepted 12th August 2014
Lijia Liu, Hongbin Wang, Runwei Wang, Shangjing Zeng, Ling Ni, Daliang Zhang,
Liangkui Zhu, Houbing zou, Shilun Qiu and Zongtao Zhang*
DOI: 10.1039/c4ra05937a
www.rsc.org/advances
Highly crystalline beta zeolite with large intracrystalline mesopores complicated amphiphilic organosilane featuring a long-chain
has been facilely synthesized via the introduction of low-cost N- alkylammonium moiety and a hydrolysable methoxysilyl group,
methyl-2-pyrrolidone (NMP) into common TEAOH-based zeolite with which they synthesized highly mesoporous zeolites with
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synthesis mixtures, which exhibited remarkably higher catalytic activity tunable mesopore structure. Besides, Verboekend et al.
contrast than conventional porous catalysts (ZSM-5, beta and Al- successfully created large amounts of intracrystalline meso-
MCM-41) in acid-catalyzed reactions involving large molecules.
porosity in bulk MFI zeolites by desilication treatment in alka-
11a
line medium followed by acid washing. With respect to these
methods, the procedural complexity and/or economic feasibility
may conict with the modern industry expectations. In our
Zeolites, with well-known physicochemical characteristics (e.g.
individual micropores, large internal surface areas, strong
acidity and high hydrothermal stability), have been successfully
3a
previous work, we have reported, for the rst time, a facile
strategy for the synthesis of hierarchical ZSM-5 with house-of-
cards-like (HCL) structure by addition of N-methyl-2-pyrroli-
done (NMP) into a template-free zeolite synthesis system. The
resulting HCL-ZSM-5 has large external surface and strong
acidity, thus exhibiting remarkable catalytic performances in
acid-catalyzed reactions concerning large molecules. Inspired
by this nding, we sought to make further efforts to bring the
NMP additive into common TEAOH-based alkaline beta zeolite
synthesis mixtures, and study the impact of such kind of
organics.
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applied in separation, ion-exchange and catalysis. In partic-
ular, the uniform micropore channels throughout the whole
zeolite framework play an irreplaceable role in the shape-
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selective catalysis, but simultaneously, also seriously limit their
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further applications in procedures involving bulky molecules.
Mesoporous materials with adjustable pore sizes of 2–50 nm
(e.g. MCM-41, MCM-48, SBA-15 and SBA-1) may offer more
accessible active sites in junction with faster mass transfer for
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effective conversion of large molecules. Regrettably, these
materials suffer from weak acidity and poor stability as a result
Mesoporous Beta (M-Beta) was hydrothermally synthesized
from an aluminosilicate sol with a typical molar composition
of 0.048Na O/0.023Al O /SiO /15.6H O/0.636TEAOH/NMP. The
2 2 3 2 2
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of their intrinsic amorphous nature of pore walls. Despite
tremendous efforts, the optimized framework crystallinity is
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still far from those of crystalline zeolites. More recently, mes-
relatively well-resolved X-ray diffraction (XRD) pattern in the 4–
oporous zeolites, with positive features of native microporous
zeolites as well as mesoporous materials, have become a hot
point in both scientic researches and industrial applications.
ꢀ
4
0 range can totally correspond to the characteristic peaks of
9b
Beta-type zeolite (Fig. 1A). As suggested by SEM and TEM
images (Fig. 2), M-Beta presents a uniform dice-like morphology
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Several strategies, involving amphiphilic organosilanes,
(300–350 nm), which consists of abundant highly crystalline
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cationic polymers, inorganic nanoparticles and post-treat-
nanocrystals (less than 30 nm). More interestingly, all these
adjacent nanocrystals exhibit the consistent lattice fringes
orientations over the entire TEM image region, meanwhile the
selected area electron diffraction (SAED) pattern assigned to
Beta-type zeolite structure shows highly discrete diffraction
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ments, have been successfully developed for the synthesis of
mesoporous zeolites. For instance, Ryoo's group developed a
State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin
University, Changchun 130012, P. R. China. E-mail: zzhang@jlu.edu.cn; Fax: +86-
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b
spots (Fig. 2D), demonstrating that dice-like M-Beta is
complete a single crystal rather than random aggregation of
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31-85168115; Tel: +86-431-85168115
†
Electronic Supplementary Information (ESI) available: Experimental and nanocrystals. N
2
adsorption–desorption isotherms take on a
characterization details, XRD patterns, N
2
adsorption–desorption isotherms, typical type IV curve with a large H4 hysteresis loop (Fig. 1B),
SEM images, TEM images, SAED pattern, textural parameters of various
catalysts. See DOI: 10.1039/c4ra05937a
indicating a micro–meso hierarchical porous textural feature.
RSC Adv., 2014, 4, 39297–39300 | 39297
This journal is © The Royal Society of Chemistry 2014