Direct Hydrothermal Synthesis of Hierarchically Porous Siliceous

Oct 9, 2009 - Rino R. Mukti, Hirotomo Hirahara, Ayae Sugawara, Atsushi Shimojima, and Tatsuya Okubo*. Department of Chemical System Engineering, The ...
0 downloads 0 Views 2MB Size
Download PDF
pubs.acs.org/Langmuir © 2009 American Chemical Society

Direct Hydrothermal Synthesis of Hierarchically Porous Siliceous Zeolite by Using Alkoxysilylated Nonionic Surfactant Rino R. Mukti, Hirotomo Hirahara, Ayae Sugawara, Atsushi Shimojima, and Tatsuya Okubo* Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan Received July 28, 2009. Revised Manuscript Received September 16, 2009 A hierarchically porous siliceous MFI zeolite (silicalite-1) with narrow mesoporosity has been hydrothermally synthesized by using trialkoxysilylated alkyl poly(oxyethylene ether) as mesopore-directing agent. A mesostructured silica-surfactant composite was formed at the early stage of the reaction, and zeolite crystallization proceeded during subsequent hydrothermal treatment. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations of the crystallized products showed that micro- and mesopores were hierarchically assembled in unique particle morphology with rugged surfaces. Solid-state 29Si and 13C NMR revealed that the covalent bonds between the zeolite framework and mesopore-directing agent were present in the products before calcination. The use of nonsilylated alkyl poly(oxyethylene ether) or a silylated alkytrimethyl-ammonium-type cationic surfactant for the synthesis of silicalite-1 resulted in a mixture of mesoporous silica and zeolite as the final product, which suggests that the covalent interaction and nonelectrostatic charge matching interaction favor the formation of hierarchically mesoporous siliceous zeolite. This alkoxysilylated nonionic surfactant can also be extended to synthesize aluminosilicate MFI zeolite (ZSM-5).

Introduction Zeolites are microporous crystalline materials that have been the most widely used catalysts in industrial processes such as oil refining and petrochemistry.1,2 The extension of their sole micropores into hierarchical pore systems consisting of both micropores and mesopores is nowadays demanded specifically for catalyzing large molecules having dimensions in the mesoporous region (2-50 nm). Such hierarchically porous zeolites or mesoporous materials with zeolitic characteristics are known to solve the phenomena of slow diffusion and coke formation, resulting in pore blockage and catalyst deactivation, that are often encountered during the heterogeneous catalytic reactions of bulky molecules.3-7 The syntheses of zeolites with hierarchical pore systems are generally achieved by complicated multistep methods such as hardtemplating,8,9 dealumination,10 and desilication.11,12 Recently, the introduction of molecular13,14 or specially designed supramolecular templates together with organic structure-directing *Corresponding author. E-mail: [email protected].

(1) Csicsery, S. M. Pure Appl. Chem. 1986, 58, 841. (2) Davis, M. E. Ind. Eng. Chem. Res. 1991, 30, 1675. (3) Christensen, C. H.; Johannsen, K.; Schmidt, I.; Christensen, C. H. J. Am. Chem. Soc. 2003, 125, 13370. (4) Corma, A. Chem. Rev. 1997, 97, 2373. (5) Zhang, Y. W.; Okubo, T.; Ogura, M. Chem. Commun. 2005, 2719. (6) Ogura, M.; Zhang, Y. W.; Elangovan, S. P.; Okubo, T. Microporous Mesoporous Mater. 2007, 101, 224. (7) Xiao, F. S.; Wang, L. F.; Yin, C. Y.; Lin, K. F.; Di, Y.; Li, J. X.; Xu, R. R.; Su, D. S.; Schloegl, R.; Yokoi, T.; Tatsumi, T. Angew. Chem., Int. Ed. 2006, 45, 3090. (8) Li, H. C.; Sakamoto, Y.; Liu, Z.; Ohsuna, T.; Terasaki, O.; Thommes, M.; Che, S. N. Microporous Mesoporous Mater. 2007, 106, 174. (9) Fan, W.; Snyder, M. A.; Kumar, S.; Lee, P. S.; Yoo, W. C.; McCormick, A. V.; Penn, R. L.; Stein, A.; Tsapatsis, M. Nat. Mater. 2008, 7, 984. (10) Corma, A.; Melo, F. V.; Rawlence, D. J. Zeolites 1990, 10, 690. (11) Groen, J. C.; Moulijn, J. A.; Perez-Ramirez, J. J. Mater. Chem. 2006, 16, 2121. (12) Ogura, M.; Shinomiya, S. Y.; Tateno, J.; Nara, Y.; Nomura, M.; Kikuchi, E.; Matsukata, M. Appl. Catal., A 2001, 219, 33. (13) Wang, J.; Groen, J. C.; Yue, W.; Zhou, W.; Coppens, M. O. Chem. Commun. 2007, 4653. (14) Choi, M.; Na, K.; Ryoo, R. Chem. Commun 2009, 2845.

Langmuir 2010, 26(4), 2731–2735

agents (OSDA)15-20 has realized the one-pot synthesis of hierarchical zeolites. The addition of some organotrialkoxysilanes has been reported to be effective for generating interparticle mesopores.15,17 Furthermore, on the basis of the surfactant-templating methodology for producing ordered mesoporous materials,21 modified cationic surfactants consisting of a hydrophobic alkyl chain and a hydrophilic quaternary ammonium head bearing an alkoxysilyl moiety have been used for preparing hierarchically porous zeolites (MFI, LTA, SOD, and FAU)18,20 with uniform mesopores and adjustable pore size by changing the alkyl chain length. The alkoxysilyl group is necessary to prevent the surfactants from being expelled from aluminosilicate domains during crystallization. Following this amphiphilic organosilanedirecting route, hierarchically porous zeolite analogues with aluminophosphate structures (AFI and AEL) have also been prepared.18,19 The use of alkoxysilylated surfactants as a mesopore-directing agent has thus opened a novel, direct route to crystalline microporous materials with unique mesostructural features. However, previous research has been limited to the use of silylated derivatives of conventional cationic surfactants for the syntheses of aluminosilicate zeolites. Apart from the practical use of zeolites in which the aluminosilicate framework provides strong acidity for catalysis,18,22 siliceous and high silica zeolites offer excellent adsorptive and catalytic properties due to their hydrophobic and internal silanol characteristics. Interestingly, the presence of (15) Serrano, D. P.; Aguado, J.; Escola, J. M.; Rodriguez, J. M.; Peral, A. Chem. Mater. 2006, 18, 2462. (16) Wang, H.; Pinnavaia, T. J. Angew. Chem., Int. Ed. 2006, 45, 7603. (17) Srivastava, R.; Iwasa, N.; Fujita, S. Chem.; Eur. J. 2008, 14, 9507. (18) Choi, M.; Cho, H.; Srivastava, R.; Venkatesan, C.; Choi, D. H.; Ryoo, R. Nat. Mater. 2006, 5, 718. (19) Choi, M.; Srivastava, R.; Ryoo, R. Chem. Commun. 2006, 4380. (20) Choi, M.; Lee, D. H.; Na, K.; Yu, B. W.; Ryoo, R. Angew. Chem., Int. Ed. 2009, 48, 3673. (21) Beck, J. S.; Vartulli, J. C.; Roth, W. J.; Leonowicz, M. E.; Kresge, C. T.; Schmitt, K. D.; Chu, C. T. W.; Olson, D. H.; Sheppard, E. W.; McCullen, S. B.; Higgins, J. B.; Schlenker, J. L. J. Am. Chem. Soc. 1992, 114, 10834. (22) Srivastava, R.; Choi, M.; Ryoo, R. Chem. Commun. 2006, 4489.

Published on Web 10/09/2009

DOI: 10.1021/la902764s

2731

Article

Mukti et al.

Figure 1. Terminally alkoxysilylated ether) (TES-C16EO10).

alkyl

poly(oxyethylene

silanol nests has been considerably advantageous for producing ε-caprolactam by the vapor phase Beckmann rearrangement of cyclohexanone oxime.23-26 Furthermore, high silica zeolite containing coalescent mesopores may increase the conversion of several linear and cyclic ketone oxime to selective amide or lactam compounds in the liquid phase Beckmann rearrangement reaction.27 Following the development of enhancing pores in aluminosilicate zeolites to expand their applications for accommodating bulky molecules,28 it is also of importance to extend siliceous and high silica zeolites into hierarchically porous-type materials. Here, we report the synthesis and the use of terminally alkoxysilylated alkyl poly(oxyethylene ether) (TES-C16EO10, shown in Figure 1) as a novel mesopore-directing agent to create hierarchically porous MFI-type zeolites. Alkyl poly(oxyethylene ether) is a typical nonionic surfactant that is low-cost, nontoxic, and biodegradable. Such surfactants generally give mesoporous materials with thick pore walls, which should be advantageous for zeolite crystallization. The addition of TES-C16EO10 enabled us to produce a pure silica MFI zeolite, silicalite-1, with narrow mesoporosity, in addition to an aluminosilicate MFI, ZSM-5. Compared to an alkoxysilylated cationic surfactant, the alkoxysilylated nonionic surfactant was found to be more effective for the synthesis of silicalite-1 with intercrystal mesoporosity. The growth processes were systematically investigated to follow the generation of mesopores along with crystallization of silicalite-1 framework.

Experimental Section Synthesis. The synthesis of TES-C16EO10 involves three steps comprising activation of substituted group, attachment of linker compound and alkoxysilyl group, and the crude products can be used without further purification. A nonionic surfactant consisting of a hydrophobic alkyl chain and a hydrophilic poly(oxyethylene) chain (C16H33O(C2H4O)10H, C16EO10 (Brij56), Aldrich) was activated with sodium hydride (Wako Pure Chemical) and reacted with allylbromide (Wako Pure Chemical). The terminal CdC double bond was silylated using triethoxysilane (Tokyo Kasei) following the literature procedure29 to give triethoxysilyl (TES)-terminated nonionic surfactant (TESC16EO10). Hierarchically porous silicalite-1 was prepared by adding TES-C16EO10 into the gel solution of silicalite-1 at room temperature followed by hydrothermal reaction in a Teflon-lined stainless steel autoclave at 393 K for several days under rotation at 20 rpm. Tetraethyl orthosilicate (TEOS, Tokyo Kasei) and tetrapropylammonium hydroxide (TPAOH, Aldrich) were used as silica source and OSDA, respectively. The molar composition of the reactants was 1 SiO2/0.19 TPAOH/25 H2O/0.05 TESC16EO10. The resulting product was washed with distilled water, recovered by centrifugation, and dried in an oven at 333 K. The (23) Lobo, R. F. AIChE J. 2008, 54, 1402. (24) Corma, A. J. Catal. 2003, 216, 298. (25) Heitmann, G. P.; Dahlhoff, G.; Hoelderich, W. F. J. Catal. 1999, 186, 12. (26) Izumi, Y.; Ichihashi, H.; Shimazu, Y.; Kitamura, M; Sato, H. Bull. Chem. Soc. Jpn. 2007, 80, 1280. (27) Camblor, M. A.; Corma, A.; Garcia, H.; Semmer-Herledan, V.; Valencia, S. J. Catal. 1998, 177, 267. (28) Perez-Ramirez, J.; Christensen, C. H.; Egeblad, K.; Christensen, C. H.; Groen, J. C. Chem. Soc. Rev. 2008, 37, 2530. (29) Urata, C.; Yamauchi, Y.; Mochizuki, D.; Kuroda, K. Chem. Lett. 2007, 36, 850.

2732 DOI: 10.1021/la902764s

Figure 2. Powder XRD patterns from the calcined products prepared using TES-C16EO10 (a) before and (b) after hydrothermal treatment for 1 day, (c) 2 days, (d) 3 days, and (e) 7 days and (f) calcined product prepared using C16EO10 after hydrothermal treatment for 2 days. Low angle patterns (left) were measured with a Rigaku RINT 2000 instrument, and high angle patterns (right) were measured with a Bruker AXS MO3X HF instrument. organic contents were removed by calcination in air at 823 K for 8 h with a heating rate of 1 K/min. For comparative purposes, silicalite-1 was synthesized with unsilylated C16EO10, alkoxysilylated cationic surfactant (octadecyldimethyl(3-trimethoxysilylpropyl)ammonium chloride, TPAOC, Gelest Inc.), or without any surfactants under otherwise identical conditions. Characterization. Powder X-ray diffraction (XRD) patterns were recorded on a Bruker AXS M03X-HF diffractometer or on a Rigaku RINT 2000 diffractometer both with Cu KR radiation. Transmission electron microscopy (TEM) observations were carried out on a JEOL JEM 2000EXII instrument operated at 200 kV. Field-emission scanning electron microscopy (FE-SEM) images were taken by using a Hitachi S-4800 instrument at an accelerating voltage of 1 kV. Solid-state 29Si CP/MAS NMR (JEOL CMX-300) spectra were recorded at a resonance frequency of 59.7 MHz, a contact time of 2 s, and a recycle delay of 5 s. Solidstate 13C MAS NMR spectra were recorded at 75.6 MHz and a recycle delay of 15 s. Nitrogen adsorption-desorption measurements were performed by using an Autosorb-1 instrument (Quantachrome Instruments) at 77 K. Samples were preheated at 423 K for 6 h under vacuum. The Brunauer-Emmett-Teller (BET) surface areas were calculated from the adsorption branch of the isotherms in the relative pressure range from 0.05 to 0.3. Pore size distributions were calculated the by BarrettJoyner-Halenda (BJH) method using the adsorption branch.

Results and Discussion Figure 2 shows the XRD patterns of calcined products in the presence of TES-C16EO10. The products before hydrothermal treatment exhibit a single, broad peak (d = 7.5 nm) characteristic of a wormhole-like mesostructure with amorphous framework. The crystalline phase of silicalite-1 appears after 2 days of hydrothermal treatment, and well-defined wide-angle XRD peaks due to MFI zeolite are observed after 3 days or later. During the hydrothermal treatment, the peak corresponding to the mesoscale structure was shifted to a lower angle and its intensity was decreased after 3 days. The diffraction lower than 0.7° of the 2θ angle is not provided because of the measurement limit of the XRD diffractometer. SEM observations reveal that silicalite-1 prepared with TESC16EO10 has an irregular aggregated morphology (after 2 days) and an almond-shape morphology (after 3 days) as shown in Langmuir 2010, 26(4), 2731–2735

Mukti et al.

Article

Figure 3. SEM images of mesoporous silicalite-1 after hydrothermal synthesis for (a) 2 days and (b) 3 days. The images for the (c) product prepared with C16EO10 and (d) conventional silicalite-1 after hydrothermal synthesis for 2 days are also shown for comparison.

Figure 4. High-resolution TEM images of mesoporous silicalite-1 after hydrothermal synthesis for (a, b) 2 days and (c, d) 3 days.

Figure 3a and b, respectively. These are quite different from the coffinlike morphology typically observed for silicalite-1. TEM study (Figure 4 and Supporting Information Figure S1) reveals that the product obtained after 2 days consists of small nanoparticles about 5 nm in diameter with interparticle mesoporosity (Figure 4a). The partial crystallization of the sample is observed as shown by lattice fringes of zeolite (Figure 4b). The homogeneous orientation of the lattice image shows a uniform crystallographic orientation within the aggregated particles. The sample formed after 3 days also has interparticle mesopores as shown in Langmuir 2010, 26(4), 2731–2735

Figure 4c while the mesopore volume seems to be reduced due to the growth of primary nanocrystals. The lattice fringes attributed to zeolite are observed everywhere in the sample (Figure 4d). The progress of crystallization observed by TEM is in good agreement with that verified in the higher angle patterns of XRD (Figure 2). The distribution of the interparticle mesopores is not so regular, which is also consistent with the relatively broad XRD patterns in the lower angle region. The mesoporosity was confirmed by nitrogen adsorptiondesorption measurement (Figure 5). Before hydrothermal DOI: 10.1021/la902764s

2733

Article

Mukti et al.

Figure 5. N2 adsorption-desorption isotherms (left) and the corresponding BJH pore size distribution (right) of the products prepared with TES-C16EO10: (a) before and (b) after hydrothermal synthesis for 1 day, (c) 2 days, (e) 3 days, and (e) 7 days. The isotherms and BJH plots of (b)-(e) are vertically offset by 150, 500, 800, 900 cm3 g-1 and 0.13, 0.3, 0.45, 0.60 cm3 g-1 nm-1, respectively. Table 1. Sorption Properties during Crystallization of Mesoporous Silicalite-1 synthesis time [day]

SBET [m2/g]

Smicro [m2/g]a

0 360 1 464 2 339 18 3 313 150 7 355 171 a Determined by t-plot method.

Vtotal [cm3/g]

Vmeso [cm3/g]

Vmicro [cm3/g]a

0.25 0.68 0.51 0.30 0.34

0.25 0.68 0.50 0.23 0.25

0.01 0.07 0.09

treatment, a type IV isotherm is observed (Figure 5a), suggesting the presence of mesopores. Although only a small mesopore volume is accessible at this stage, it increased after 1 day of hydrothermal treatment (see Table 1). When silicalite-1 is crystallized after further hydrothermal treatment for 2 days, the mesoporosity is still retained but the pore volumes are slightly declined, suggesting the presence of meso- and micropores in such a hierarchical system. As the crystallization further proceeds (after 3 days), the mesopore volume is significantly reduced but narrow mesoporosity is generated. Eventually, the crystallinity of zeolite remains unchanged after hydrothermal treatment for 7 days, which suggests that ripening of the crystalline zeolite framework has fully proceeded. At this stage, the narrow mesoporosity and mesopore volume are still retained, showing a positive indication in which the final product of mesoporous silicalite-1 can be attained with enhanced properties. It is well-known that noncovalent incorporation of surfactants during nucleation and crystallization of zeolite is not sufficient to generate mesoporosity.17 Actually, the use of nonsilylated C16EO10, commonly used in the syntheses of mesostructured silica materials,29,30 resulted in the formation of highly crystalline silicalite-1 with only small mesopore volume (0.17 cm3/g). The SEM image shows a typical coffinlike crystal of MFI zeolite with a twin intergrowth characteristic (Figure 3c), which is quite (30) Zhao, D. Y.; Huo, Q. S.; Feng, J. L.; Chmelka, B. F.; Stucky, G. D. J. Am. Chem. Soc. 1998, 120, 6024.

2734 DOI: 10.1021/la902764s

Figure 6. 29Si CP/MAS NMR (left) and 13C MAS NMR spectra (right) for as-synthesized materials prepared with TES-C16EO10: (a) before and (b) after hydrothermal treatment for 2 days and (c) 3 days. Peak assignments: O and b refer to the carbon atoms from TES-C16EO10 and TPAþ, respectively.

similar to that observed when C16EO10 was not added for the synthesis (Figure 3d). Moreover, as expected from the absence of any peak in the low-angle XRD pattern (Figure 2f), this product does not have narrow mesopores arising from interparticle voids. These results suggest that the functionalization of silica walls by a covalently bonded amphiphile is essential for the formation of mesoporous zeolite in a hierarchical system. The solid-state 29Si CP/MAS NMR spectra of the as-synthesized samples before and after hydrothermal treatment (Figure 6, left) show the presence of the T sites (C-SiO3) derived from TESC16EO10 along with the Q3 and Q4 sites derived from TEOS. In addition, 13C MAS NMR spectra (Figure 6, right) show the signals assigned to alkyl chains and poly(oxyethylene) chains along with those of TPA cations.31 The molar compositions of C16EO10SiO1.5/TPAþ/SiO2 were calculated by combining CHN elemental analysis and thermogravimetry. The C16EO10-SiO1.5/SiO2 ratio was constant until after 2 days of hydrothermal synthesis and subsequently decreased from 0.038 to 0.008 when the zeolite crystallinity was saturated in 3 days. These results are in agreement with the sorption data showing that the decrease of the mesopore volume occurs, accompanied by the increase of the micropore volume. It is plausible that a part of C16EO10-SiO1.5 species retained in the sample even after crystallization is acting as a template to generate narrow mesopores. Note that the TPAþ/SiO2 ratio after 3 days was 0.05, which is close to the theoretical value of having four TPAþ molecules per unit cell assuming the interaction at all intersections between the straight and sinusoidal channel. We have also examined the procedure using alkoxysilylated cationic surfactant (octadecyldimethyl(3-trimethoxysilylpropyl) ammonium chloride) to synthesize hierarchical silicalite-1 under the same conditions, but the resultant material was merely a physical mixture of siliceous zeolite and mesostructured silica (see the Supporting Information, Figure S2). This fact suggests that, for establishing mesoporous silicalite-1, nonionic-type interactions involving hydrogen-bonding between PEO chains and silicate species is indeed necessary in addition to the covalent bonds due to the alkoxysilyl group at least under our experimental conditions. Mesoporous ZSM-5, an aluminosilicate MFI zeolite, can also be prepared by using TES-C16EO10 with aluminum isopropoxide as an Al source (see the Supporting Information for experimental details and Figures S3 and S4). A wormhole-like mesostructure is (31) Wan, Y.; Zhao, D. Y. Chem. Rev. 2007, 107, 2821.

Langmuir 2010, 26(4), 2731–2735

Mukti et al.

Article

Conclusion

Figure 7. N2 adsorption-desorption isotherms (left) and BJH pore size distribution (right) of mesoporous zeolites after hydrothermal treatment for 3 days.

formed at the initial stage of the reaction, and crystallization of ZSM-5 occurred after hydrothermal treatment for 1 day. The Si/ Al ratio of the product after 7 days was 26.8 as determined by inductively coupled plasma (ICP) analysis. The mesopore diameter (centered at 5 nm) after 2 days is larger than that for mesoporous ZSM-5 prepared by using alkoxysilylated cationic surfactant with the same alkyl chain length (3.1 nm),17 which should be due to the larger hydrophilic headgroup of C16EO10 (see the Supporting Information, Figure S5). Unlike the aforementioned mesoporous silicalite-1, a narrow mesopore distribution in mesoporous ZSM-5 was not achieved (Figure 7), although the mesopore volume is higher (0.43 cm3/g). Such a difference might be due to the difference in the roles of the mesopore-directing agent in the neutral siliceous framework and charged aluminosilicate framework. The enhancement of mesopore volume in mesoporous ZSM-5 can be uniquely achieved by adding TES-C16EO10 to the ZSM-5 gel solution that was preheated at 353 K for 24 h. On hydrothermal synthesis for 2 days, the mesopore volume increased twice as much as that when the gel solution was prepared at room temperature. Additionally, the mesopore diameter was enhanced and centered at 5.9 nm in contrast to 4.2 nm as a result when the gel solution was prepared at room temperature (see the Supporting Information, Figure S6). It is speculated that the rates of nucleation and crystal growth play a significant role in the formation of mesoporous ZSM-5. A similar phenomenon was not observed in the case of silicalite-1, but further studies on this subject are underway.

Langmuir 2010, 26(4), 2731–2735

We have demonstrated that the designed nonionic surfactant-directing route employing alkoxysilylated alkyl poly(oxyethylene ether) is a promising pathway for the syntheses of hierarchically porous zeolites, particularly siliceous zeolite such as silicalite-1. The silylated alkyl poly(oxyethylene ether) appears to be more suitable than the silylated-alkyltrimethylammonium-type cationic surfactant for the synthesis of mesoporous silicalite-1. The implementation of widely known nonionic surfactants, which are low-cost, nontoxic, and biodegradable, further adds to the value of the current synthesis strategy. However, TEOS as silica source and TPAOH as OSDA are considered to be expensive, and they should be replaced in the future by less expensive chemicals such as fumed silica and sodium hydroxide, respectively, toward truly low-cost synthesis of mesoporous zeolites. To the best of our knowledge, this is the first example of the synthesis of mesoporous silicalite-1 in a hierarchical system by the surfactant-directed hydrothermal assembly process. We expect that our approach can be extended to various hydrophobic zeolites with high Si/Al ratio up to infinity. Acknowledgment. This work was partially supported by a Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (JSPS) which was awarded to T.O. R.R.M. acknowledges JSPS for awarding a postdoctoral fellowship. A.S. acknowledges the support from a Grant-in-Aid for Young Scientists (B) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan. A part of this work was conducted in the Center for Nano Lithography & Analysis, The University of Tokyo, supported by the MEXT, Japan. We are grateful to Dr. S. P. Elangovan (Nippon Chemical Industrial Co., Ltd.), Dr. K. Itabashi, Dr. R. Supplit, Dr. K. K. Cheralathan, and Assoc. Prof. M. Ogura (The University of Tokyo) for stimulating discussion, and also to Prof. S. Maruyama and Dr. Y. Murakami (The University of Tokyo) for use of the SEM instrument and Mr. K. Ibe for assistance in TEM observation. Supporting Information Available: More TEM images of mesoporous silicalite-1 synthesized using TES-C16EO10 and the synthesis procedure of mesoporous ZSM-5 using alkoxysilyated nonionic surfactant as well as XRD, SEM, and N2 sorption results of mesoporous ZSM-5. In addition, XRD result and SEM image showing the mixture of mesoporous silica and silicalite-1 synthesized using alkoxysilylated cationic surfactant. This material is available free of charge via the Internet at http://pubs.acs.org.

DOI: 10.1021/la902764s

2735