Synthesis Mechanism of Cationic Surfactant Templating Mesoporous Silica under an Acidic Synthesis Process Shunai Che,* ,† Huachun Li, † Sunghyun Lim, ‡ Yasuhiro Sakamoto, § Osamu Terasaki, § and Takashi Tatsumi* ,‡,| Department of Chemistry, School of Chemistry and Chemical Technology, Shanghai Jiao Tong UniVersity, 800 Dongchuan Road, Shanghai 200240, People’s Republic of China, Structural Chemistry, Arrhenius Laboratory, Stockholm UniVersity, S-10691 Stockholm, Sweden, DiVision of Materials Science & Chemical Engineering, Faculty of Engineering, Yokohama National UniVersity, 79-5 Tokiwadai, Yokohama 240-8501, Japan, and CREST, JST, Japan ReceiVed February 17, 2005. ReVised Manuscript ReceiVed June 16, 2005 The presence of various counteranions in the interfacial region of the silicate-surfactant mesophase introduces opportunities for manipulation of the phase structure. Well-ordered three-dimensional hexagonal P6 3 /mmc, cubic Pm3 hn, two-dimensional hexagonal p6mm, and cubic Ia3 hd mesoporous materials have been synthesized with the same surfactant (cetyltriethylammonium bromide), depending on the kind of acids. The counteranions of acidic media have resulted in increasing surfactant packing parameter g in the order SO 4 2- < Cl - < Br - < NO 3 - , which leads to different formation routes to the mesostructures. It has been found that the mesophases are always transformed from the lower curvature one into the higher curvature one in the acidic synthesis gel. The combination of X-ray diffraction patterns, scanning electron microscope images, and high-resolution transmission electron microscope images presented visible evidence for the mesostructural constructions. In particular, the synthesis of a cubic Pm3 hn mesoporous molecular sieve was studied in the presence of trimethylbenzene (TMB) isomers. The rate of transformation is greatly affected by the structure of the TMB isomers and their content; 1,2,3-TMB was the most favorable to the stabilization of the p6mm hexagonal mesophase, 1,3,5-TMB was the least favorable, and 1,2,4-TMB showed intermediate behavior. Introduction Since the first discovery of mesoporous materials (FSM- 16 1 and M41S families 2 ) was made by Yanagisawa et al. and Mobil Research, respectively, other phases such as SBA- n, 3 HMS-n, 4 KIT-n, 5 FDU-n, 6 and AMS-n 7 have been reported. These mesoporous materials attract a great deal of attention because of their controllable structures and com- positions, which make them suitable for wide applications in catalysis, environmental cleanup, and advanced materials design. The understanding of the mechanism relating to surfactant-templated reaction should ultimately lead to a more rational approach to the synthesis of mesoporous materials. There have been a number of models proposed to explain the formation of mesopores and to provide a rational basis for the various synthesis routes. 8 Huo and co-workers 4b proposed a generalized liquid crystal templating mechanism based on the specific type of electrostatic interaction between a given inorganic precursor I and a surfactant headgroup S. The basic synthesis route involves the direct co-condensation * To whom correspondence should be addressed. E-mail: chesa@ sjtu.edu.cn (S.C.); ttatsumi@ynu.ac.jp (T.T.). † Shanghai Jiao Tong University. ‡ Yokohama National University. § Stockholm University. | CREST. (1) Yanagisawa, T.; Shimizu, T.; Kuroda, K.; Kato, D. Bull. Chem. Soc. Jpn. 1990, 63, 988. (2) (a) Kresge, C. T.; Leonowicz, M. E.; Roth, W. J.; Vartuli, J. C.; Beck, J. S.; Nature 1992, 359, 710. (b) Beck, J. S.; Vartuli, 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. Chem. Soc. 1992, 114, 10834. (3) (a) Huo, Q.; Margolese, D. I.; Ciesla, U.; Feng, P.; Gier, T. E.; Sieger, P.; Leon, R.; Petroff, P. M.; Schu ¨th, F.; Stucky, G. D. Nature 1994, 368, 317. (b) Huo, Q.; Margolese, D. I.; Ciesla, U.; Demuth, D. G.; Feng, P.; Gier, T. E.; Sieger, P.; Firouzi, A.; Chmelka, B. F.; Schu ¨th, F.; Stucky, G. D. Chem. Mater. 1994, 6, 1176. (c) Huo, Q.; Leon, R.; Petroff, P. M.; Stucky, G. D. Science 1995, 268, 1324. (d) Huo, Q.; Margolese, D. I.; Stucky, G. D. Chem. Mater. 1996, 8, 1147. (e) Zhao, D.; Feng, J.; Huo, Q.; Melosh, N.; Fredrickson, G. H.; Chmelka, B. F.; Stucky, G. D. Science 1998, 279, 548. (f) Zhao, D.; Huo, Q.; Feng, J.; Chmelka, B. F.; Stucky, G. D. J. Am. Chem. Soc. 1998, 120, 6024. (4) (a) Tanev, P. T.; Pinnavaia, T. J. A neutral templating route to mesoporous molecular-sieves. Science 1995, 267, 865. (b) Bagshaw, S. A.; Prouzet, E.; Pinnavaia, T. J. Science 1995, 269, 1242. (5) (a) Ryoo, R.; Kim, J. M.; Ko, C. H.; Shin, C. H. J. Phys. Chem. 1996, 100, 17718. (b) Kleitz, F.; Choi, S. H.; Ryoo, R. Chem. Commun. 2003, 2136. (6) (a) Yu, C.; Tian, B.; Fan, J.; Stucky, G. D.; Zhao, D. J. Am. Chem. Soc. 2002, 124, 4556. (b) Liu, X.; Tian, B.; Yu, C.; Gao, F.; Xie, S.; Tu, B.; Che, R.; Peng, L.; Zhao, D. Angew. Chem., Int. Ed. 2002, 41, 3876. (c) Yang, H.; Shi, Q.; Liu, X.; Xie, S.; Jiang, D.; Zhang, F.; Yu, C.; Tu, B.; Zhao, D. Chem. Commun. 2002, 23, 2842. (d) Yu, C.; Tian, B.; Fan, J.; Stucky, G. D.; Zhao, D. J. Am. Chem. Soc. 2002, 124, 4556. (7) (a) Che, S.; Garcia-Bennett, A. E.; Yokoi, T.; Sakamoto, K.; Kunieda, H.; Terasaki, O.; Tatsumi, T. Nat. Mater. 2003, 2, 801. (b) Garcia- Bennett, A. E.; Terasaki, O.; Che, S.; Tatsumi, T. Chem. Mater. 2004, 16, 813. (c) Che, S.; Liu, Z.; Ohsuna, T.; Sakamoto, K.; Terasaki, O.; Tatsumi, T. Nature 2004, 429, 281. (8) (a) Chen, C. Y.; Li, H. Y.; Davis, M. E. Microporous Mater. 1993, 2, 27. (b) Steel, A.; Carr, S. W.; Anderson, M. W. J. Chem. Soc. Chem. 1994, 1571. (c) Monnier, A.; Schu ¨th, F.; Huo, Q.; Kumar, D.; Margolese, D.; Maxwell, R. S.; Stucky, G. D.; Krishnamurty, M.; Petroff, P.; Firouzi, A.; Janicke, M.; Chemelka, B. F. Science 1993, 261, 1299. (d) Firouzi, A.; Kumar, D.; Bull, M. L.; Besier, T.; Sieger, P.; Huo, Q.; Walker, S. A.; Zasadzinski, J. A.; Glinka, C.; Nicol, J.; Margolese, D.; Stucky, G. D. Science 1995, 267, 1138. 4103 Chem. Mater. 2005, 17, 4103-4113 10.1021/cm050359s CCC: $30.25 © 2005 American Chemical Society Published on Web 07/15/2005