COMMUNICATIONS 2346  WILEY-VCH Verlag GmbH, D-69451 Weinheim, 2000 1433-7851/00/3913-2346 $ 17.50+.50/0 Angew. Chem. Int. Ed. 2000, 39, No. 13 Synthesis, Characterization, and Catalytic Activity of a Large-Pore Tridirectional Zeolite, H-ITQ-7** Avelino Corma,* María Jose  Díaz-Caban Äas, and Vicente Forne Âs Zeolites are probably the most widely used solid catalysts in refining, petrochemistry, and fine chemical production. This is especially true for the acid zeolites, (H-zeolites). Their success is derived from properties such as high surface area, high adsorption capacity, molecular sieve characteristics, and the possibility of preparation with a well defined number of uniformly active sites; [1] these sites are introduced by direct synthesis or by postchemical treatment. [2] Considering the channel size, zeolites are classified as ultralarge (> 12 membered rings (MR)), large (12-MR), medium (10-MR) or small (8-MR) pore materials depending on the number of T atoms that limits the pore aperture of their largest channels (T represents atoms from the aluminum and silicon families). While zeolites with small pores have found some specific applications in, for instance, the conversion of methanol to olefins [3] , the most successful zeolitic catalysts are those based on zeolites with medium and large pores. More specifically, large-pore zeolites have unique properties for dealing with many of the oil fractions involved in refinery processes (cracking, hydrocracking, hydroisomerization, among others), in petrochemistry (including benzene alkylation with olefins, isomerization and disproportionation of alkylaromatic spe- cies), and in fine chemical production (such as alkylation, acylation, isomerization, and esterification). It must be noted, for many of the processes named above, a rapid diffusion of the reactants and products is desired and this is better achieved with large-pore tridirectional zeolites. Until recently, however, only two large-pore tridirectional zeolites were synthesized, faujasite and Beta, and of these only the Beta zeolite can be directly synthesized with a high Si:Al ratio and therefore does not need, unlike the faujasites, a postsynthesis dealumination. Therefore, owing to the large catalytic interest and very limited number of large-pore tridirectional zeolites, a considerable effort has been devoted in the last decade to produce such structures [4] . Very recently, [5] the pure silica form of a new large-pore tridirec- tional zeolite has been presented, named ITQ-7 (Instituto de Tecnología Química-7). Unfortunately, the authors were unable to introduce acidity into ITQ-7 by direct synthesis with the trivalent (Al and Ga family) atoms in an isomorph- ically substituted zeolite [6] . Therefore, this large-pore tridirec- tional zeolite have had no possibilities in catalysis since only the purely siliceous form was available. Herein, we present the possibility to synthesize ITQ-7 with different T III and T IV elements isomorphically incorporated into the framework and, in this way, acidic, catalytically active ITQ-7 materials have been prepared. The synthesis of isomorphically substituted zeolites was attempted following two strategies. The first strategy consists of synthesizing a boron-containing ITQ-7 (B-ITQ-7) sample which already should present some weak acidity and then, in a further step, to exchange B with Al to yield materials, named B/Al-ITQ-7, with a much greater acidity than the B-ITQ-7 precursor. The second strategy involves the direct synthesis of Al-ITQ-7. The two synthesis routes will be described below. B-ITQ-7: Boron-containing ITQ-7 was formed from a gel with the composition SiO 2 :B 2 O 3 :C 14 H 26 NOH:HF:H 2 O in a molar ratio 1.0:0.01:0.50:0.50:3.0, where C 14 H 26 NOH is 1,3,3- trimethyl-6-azonium-tricyclo[3.2.1.4 6,6 ]dodecane hydroxide. The gel was prepared by dissolving H 3 BO 3 (0.08 g) in a solution of C 14 H 26 NOH (0.99 m, 31.98 g). Tetraethylorthosili- cate (TEOS, 13.46 g) was then hydrolyzed in the solution and the mixture was stirred gently to completely evaporated the ethanol formed. Finally, HF (1.34 g as 48.1% in water) and purely siliceous ITQ-7 crystals (0.20 g) were added and the mixture was homogeneized. After 7 days crystallization at [6] M. Sono, M. P. Roach, E. D. Coulter, J. H. Dawson, Chem. Rev . 1996, 96, 2841±2887. [7] B. J. Wallar, J. D. Lipscomb, Chem. Rev . 1996, 96, 2625±2657. [8] D. T. Sawyer, A. Sobkowiak, T. Matsushita, Acc. Chem. Res. 1996, 29, 409±416. [9] M. Newcomb, P.A. Simakov, S.-U. Park, Tetrahedron Lett. 1996, 37 , 819±822. [10] P. A. MacFaul, K. U. Ingold, D. D. M. Wayner, L. QueJr., J. Am. Chem. Soc. 1997 , 119,10594±10598. [11] a)F. Minisci, F. Fontana, S. Araneo, F. Recupero, L. Zhao, Synlett 1996, 119 ± 125; b) D. H. R. Barton, Synlett 1997 , 229±230. [12] B. Meunier, Chem. Rev . 1992, 92, 1411±1456. [13] M. J. Perkins, Chem. Soc. Rev . 1996, 229±236. [14] M. Newcomb, P.A. Simakov, S.-U. Park, Tetrahedron Lett. 1996, 37 , 819±822. [15] V. I. Ponomarev, O. S. Filipenko, L. O. Atovmyan, S. A. Bobkova, K. I. Turte Á, Sov. Phys. Dokl. 1982, 27 ,6±9. [16] Crystal data for 3 (213 K) with Mo Ka radiation (l  0.71073 ): orthorhombic, space group Pccn, a  16.698(5), b  9.074(2), c  16.587(4) , V  2513(1)  3 , Z  4, R 1  0.0478 for 2156 data with I > 2s(I), GOF (on F 2 )  1.108. For 4 (213 K): orthorhombic, space group P2 1 2 1 2 1 , a  13.3830(1), b  16.4843(2), c  24.1315(2) , V  5323.60(8)  3 , Z  4, R 1  0.0327 for 9486 data with I > 2s(I), GOF (on F 2 )  1.055. Further details on the crystal structure investigations may be obtained from the Fachinformationszentrum Karlsruhe, 76344 Eggenstein-Leopoldshafen, Germany (fax: ( 49)7247-808-666; e-mail: crysdata@fiz-karlsruhe.de), on quoting the depository num- bers CSD-411108 (3) and -411109 (4). [17] F. Minisci, E. Vismara, F. Fontana, Heterocycles 1989, 28, 489±519. [18] F. Recupero, A. Bravo, H.-R. Bjùrsvik, F. Fontana, F. Minisci, M. Piredda, J. Chem. Soc. Perkin Trans. 2 1997 , 2399±2405. [19] D.H.R. Barton, F. Halley, N. Ozbalik, M. Schmitt, E. Young, G. Balavoine, J. Am. Chem. Soc. 1989, 111, 7144±7149. [20] G. V. Buxton, C. L. Greenstock, W. P. Helman, A. B. Ross, J. Phys. Chem. Ref. Data 1988, 17 , 513±886. [21] F. Minisci, A. Citterio, E. Vismara, Tetrahedron 1985, 41, 4157±4170. [22] S. Kiani, A. Tapper, R. J. Staples, P. Stavropoulos, J. Am. Chem. Soc. , submitted. [23] D. H. R. Barton, B. Hu, D. K. Taylor, R. U. Rojas Wahl, J. Chem. Soc. Perkin Trans. 2 1996, 1031±1041. [*] Prof. A. Corma, M. J. Díaz-Caban Äas, V. Forne Âs Instituto de Tecnología Química UPV-CVSIC Universidad Polite Âcnica de Valencia Avda. de los Naranjos s/n, 46022 Valencia (Spain) Fax: ( 34)96-387-78-09 E-mail: acorma@itq.upv.es [**] We thank the Spanish CICYT for financial support (Project MAT97- 1016-C02-01).