Communication
ChemComm
the ESI†) and showed very similar high CHO conversion (92% The hierarchical silicalite-1 octahedra exhibited excellent and
initially and decreased to 60% after 45 h) but lower CL selectivity stable activity for the vapor-phase Beckmann rearrangement
(70% initially, increased to B80% within 10 h, and then remained and high lactam selectivity. The results demonstrate a new
at 80–83% afterwards) than the acid-treated hierarchical silicalite-1 design rule of the SDA for preparing novel hierarchical zeolites
octahedra did (Fig. S9 in the ESI†). A sample of solvent-extracted for catalytic and other applications.
MCM-41 that is known to have a silanol-enriched mesopore
The authors thank the Ministry of Science and Technology
surface30,31 was also prepared and tested for the reaction. It gave of Taiwan for the financial support under contract MOST
an initial CHO conversion of 80% that promptly decreased to 103-2628-M-007-006-MY3.
50% within 5 h and then continuously decreased to 20% after an
on-stream time of 60 h, and the CL selectivity remained in between
55 and 65% for most of the on-stream time (Fig. S10 in the ESI†).
Obviously, the long catalytic lifetime of the calcined and acid-
treated silicalite-1 octahedra comprising highly-branched and
Notes and references
1 J. Cejka and S. Mintova, Catal. Rev.: Sci. Eng., 2007, 49, 457.
2 A. Corma, M. Diaz-Cabanas, J. Martinez-Triguero, F. Rey and J. Rius,
Nature, 2002, 418, 514.
orthogonally-stacked nanoplates can be associated with the inherent
hierarchical porosity to facilitate facile diffusion,21 and the distinct
behavior on the CL selectivity may be correlated with the type of
catalytically active site, i.e. surface silanols, in the catalysts:18,19,32,33
the isolated and vicinal silanol groups are the active sites for the
calcined silicalite-1 octahedra, bulk silicalite-1 and solvent-extracted
MCM-41, and the highly hydrogen-bonding silanol nest-like species,
most likely at the perpendicular nanoplate junctions, may be
responsible for the superior and stable catalytic activity of the
3 M. E. Davis, Nature, 2002, 417, 813.
4 W. Vermeiren and J. P. Gilson, Top. Catal., 2009, 52, 1131.
5 X. Xu, J. Wang and Y. Long, Sensors, 2006, 6, 1751.
6 A. H. Janssen, A. J. Koster and K. P. de Jong, Angew. Chem., Int. Ed.,
2001, 40, 1102.
7 V. Valtchev, G. Majano, S. Mintova and J. Perez-Ramirez, Chem. Soc.
Rev., 2013, 42, 263.
8 M. W. Anderson, S. M. Holmes, N. Hanif and C. S. Cundy, Angew.
Chem., Int. Ed., 2000, 39, 2707.
9 M. Choi, H. S. Cho, R. Srivastava, C. Venkatesan, D. H. Choi and
R. Ryoo, Nat. Mater., 2006, 5, 718.
10 H. Wang and T. J. Pinnavaia, Angew. Chem., Int. Ed., 2006, 45, 7603.
acid-treated silicalite-1 octahedra. For the acid-treated silicalite-1 11 M. Choi, K. Na, J. Kim, Y. Sakamoto, O. Terasaki and R. Ryoo,
Nature, 2009, 461, 246.
12 K. Na, C. Jo, J. Kim, K. Cho, J. Jung, Y. Seo, R. J. Messinger,
particles synthesized with N3–PO33–N3, the presence of fewer
silanol nest-like species may account for its lower CL selectivity
B. F. Chmelka and R. Ryoo, Science, 2011, 333, 328.
than that for the acid-treated silicalite-1 octahedra. Interestingly, 13 W. Park, D. Yu, K. Na, K. E. Jelfs, B. Slater, Y. Sakamoto and R. Ryoo,
Chem. Mater., 2011, 23, 5131.
14 B. Y. Liu, Q. Q. Duan, C. Li, Z. H. Zhu, H. X. Xi and Y. Qian, New
we found that the silicalite-1 octahedra could also catalyze the
Beckmann rearrangement of cycloocatanone oxime (COO), an
J. Chem., 2014, 38, 4380.
oxime that is larger than the micropore of the MFI zeolite.20 15 R. Kore, R. Srivastava and B. Satpati, Chem. – Eur. J., 2014, 20, 11511.
16 D. D. Xu, Y. H. Ma, Z. F. Jing, L. Han, B. Singh, J. Feng, X. F. Shen,
Although both the calcined and acid-treated silicalite-1 octa-
hedra showed a similar and relatively steady COO conversion of
F. L. Cao, P. Oleynikov, H. Sun, O. Terasaki and S. N. Che, Nat.
Commun., 2014, 5, 4262.
15–20% after an on-stream time of 10 h, only the acid-treated 17 D. D. Xu, Z. F. Jing, F. L. Cao, H. Sun and S. N. Che, Chem. Mater.,
2014, 26, 4612.
sample produced the corresponding lactam with a selectivity of
65–75% (Fig. S11 in the ESI†). The results clearly indicate that
18 G. P. Heitmann, G. Dahlhoff and W. F. Holderich, J. Catal., 1999, 186, 12.
19 A. B. Fernandez, A. Marinas, T. Blasco, V. Fornes and A. Corma,
the unique, silanol nest-like species in the acid-treated silicalite-
1 octahedra are catalytically active for the vapor-phase Beckmann
rearrangement reactions.
J. Catal., 2006, 243, 270.
20 H. Ichihashi, M. Ishida, A. Shiga, M. Kitamura, T. Suzuki,
K. Suenobu and K. Sugita, Catal. Surv. Asia, 2003, 7, 261.
21 J. Kim, W. Park and R. Ryoo, ACS Catal., 2011, 1, 337.
´
The reusability of the acid-treated silicalite-1 octahedra for 22 I. Dıaz, E. Kokkoli, O. Terasaki and M. Tsapatsis, Chem. Mater.,
2004, 16, 5226.
the rearrangement of CHO into CL was also examined (detailed
conditions provided in the ESI†). After the first cycle of the
23 W. Chaikittisilp, Y. Suzuki, R. R. Mukti, T. Suzuki, K. Sugita, K. Itabashi,
A. Shimojima and T. Okubo, Angew. Chem., Int. Ed., 2013, 52, 3355.
´
catalytic test, the regenerated sample still exhibited very high 24 G. Bonilla, I. Dıaz, M. Tsapatsis, H.-K. Jeong, Y. Lee and D. G.
Vlachos, Chem. Mater., 2004, 16, 5697.
25 X. Y. Zhang, D. X. Liu, D. D. Xu, S. Asahina, K. A. Cychosz, K. V.
(B95%) and stable CL selectivity but gave a lower initial CHO
conversion of 80% that gradually decreased to 41% and became
Agrawal, Y. Al Wahedi, A. Bhan, S. Al Hashimi, O. Terasaki,
stable (Fig. S12 in the ESI†). The catalytic performance remained
nearly unchanged in the third and fourth catalytic cycles. The
decreased catalytic activity seemed to correlate with the decreased
amount of silanol species as evidenced by solid-state 29Si MAS NMR
(showing a decrease of the Q3/(Q3 + Q4) ratio from 25% for the acid-
treated sample to 13%) and FT-IR (Fig. S13a and b in the ESI†). The
M. Thommes and M. Tsapatsis, Science, 2012, 336, 1684.
´
´
26 J. C. Groen, L. A. A. Peffer and J. Perez-Ramırez, Microporous
Mesoporous Mater., 2003, 60, 1.
27 K. Varoon, X. Y. Zhang, B. Elyassi, D. D. Brewer, M. Gettel, S. Kumar,
J. A. Lee, S. Maheshwari, A. Mittal, C. Y. Sung, M. Cococcioni, L. F. Francis,
A. V. McCormick, K. A. Mkhoyan and M. Tsapatsis, Science, 2011, 334, 72.
28 C.-M. Yang, B. Zibrowius, W. Schmidt and F. Schu¨th, Chem. Mater.,
2004, 16, 2918.
recycled silicalite-1 octahedra did not show discernable structural 29 C.-M. Yang, B. Zibrowius, W. Schmidt and F. Schu¨th, Chem. Mater.,
2003, 15, 3739.
30 N. Lang and A. Tuel, Chem. Mater., 2004, 16, 1961.
31 C.-J. Lin, S.-H. Huang, N.-C. Lai and C.-M. Yang, ACS Catal., 2015,
and morphological changes (Fig. S13c and d in the ESI†).
In summary, we have designed a new type of triblock SDA
for the direct synthesis of hierarchical silicalite-1 octahedra
with highly-branched and self-pillared nanoplates. The ortho-
gonal stacking of nanoplates is associated with the forma-
tion of silanol nest-like species at the junction of nanoplates.
5, 4121.
32 Y. Izumi, H. Ichihashi, Y. Shimazu, M. Kitamura and H. Sato, Bull.
Chem. Soc. Jpn., 2007, 80, 1280.
33 G. Dahlhoff, J. P. M. Niederer and W. F. Hoelderich, Catal. Rev.: Sci.
Eng., 2001, 43, 381.
Chem. Commun.
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