Synthesis and Characterization of ERI-Type UZM-12 Zeolites and Their Methanol-to-Olefin Performance Joo Hyuck Lee, † Min Bum Park, † Jun Kyu Lee, † Hyung-Ki Min, † Mee Kyung Song, ‡ and Suk Bong Hong* ,† Department of Chemical Engineering and School of EnVironmental Science and Engineering, POSTECH, Pohang 790-784, Korea, and Center for Nanomaterials, Sogang UniVersity, Seoul 121-742, Korea Received June 14, 2010; E-mail: sbhong@postech.ac.kr Abstract: A wide variety of different linear, diquaternary alkylammonium ions have been used as supplementary crystallization structure-directing agents (SDAs) in the synthesis of UZM-12, a high-silica version of zeolite erionite, via a charge density mismatch (CDM) approach. When tetraethylammonium is used as a CDM SDA, the crystallization of UZM-12 was found to be critically dependent not only on the type of alkali metal cations added as another crystallization SDA to the synthesis mixture, but also on the size of the groups on the diquaternary ammonium ion employed and the length of its central polymethylene chain that are closely related to the dimensions of cylindrical 23-hedral [4 12 6 5 8 6 ] eri cages in this small- pore zeolite. 27 Al MQ MAS NMR measurements reveal a preferential location of Al on the high-multiplicity site over the lower-multiplicity site of the UZM-12 framework. The catalytic results from the methanol-to- olefin reaction over a series of H-UZM-12 zeolites with similar acidic properties but different crystallite sizes (100-2500 nm in length) demonstrate that the nanocrystallinity (probably the e100 nm range) may have a detrimental effect on the activity and stability for this reaction, probably due to the fast buildup of large coke molecules on the external surface of zeolite crystallites that inhibits the methanol diffusion to intrazeolitic acid sites, rendering them ultimately inaccessible for catalysis. Introduction UZM-12, which is a high-silica analogue of the rare natural zeolite erionite (framework type ERI), is among the alumino- silicate zeolites with already known framework structures but previously unobserved chemical compositions that workers at UOP have recently synthesized using the so-called charge density mismatch (CDM) approach. 1-3 This new strategy holds some degree of rational design for new zeolite structures, because it includes the objective of leading to a cooperative structure direction with multiple structure-directing agents (SDAs) and/or a more favorable match with the negative framework charge density of the resulting aluminosilicate product. The ERI structure consists of columns of 11-hedral [4 6 6 5 ] can cages that are joined by double 6-rings in the c-axis, while being alternatively rotated by 60°. 4 Adjacent columns are linked by single 6-rings connecting can cages at the same level, forming the larger cylindrical 23-hedral [4 12 6 5 8 6 ] eri cages with 6.3 Å in diameter and 13.0 Å in height 5 that can be accessible through elliptical 8-ring (3.6 × 5.1 Å) windows. UZM-12 has been reported to crystallize at Si/Al ratios >5.5 through the combined use of tetraethylammonium (TEA + ) as a CDM SDA and N,N,N,N′,N′,N′-hexamethylbutanediammonium ((CH 3 ) 3 - N + (CH 2 ) 4 N + (CH 3 ) 3 , Me 6 -diquat-4), N,N,N,N′,N′,N′-hexameth- ylhexanediammonium ((CH 3 ) 3 N + (CH 2 ) 6 N + (CH 3 ) 3 , Me 6 -diquat- 6), or benzyltrimethylammonium ion as an organic crystallization SDA in the presence of K + . 2 Also, this small-pore zeolite is known to vary in crystallite size and morphology from the micrometric to the nanometric range and from the spherical to needlelike shape, respectively, depending on the type of the organic crystallization SDA employed, as well as on the K + /Al ratio of synthesis mixtures. It is well-established that the use of organic SDAs with a high degree of flexibility and hydrophilicity, instead of confor- mationally rigid and bulky (and thus relatively hydrophobic) ones, in zeolite syntheses is another viable strategy for the discovery of previously unobserved framework structures. 6 In this respect, Me 6 -diquat-6 is remarkable, because it can direct the formation of a number of different zeolite structures: EU-1 (EUO), ZSM-12 (MTW), ZSM-23 (MTT), NU-87 (NES), and ZSM-48 (*MRE) in alkaline media 7 and various new phases † POSTECH. ‡ Sogang University. (1) (a) Blackwell, C. S.; et al. Angew. Chem., Int. Ed. 2003, 42, 1737. (b) Lewis, G. J.; Miller, M. A.; Moscoso, J. G.; Knight, L. M.; Wilson, S. T. Stud. Surf. Sci. Catal. 2004, 154, 364. (c) Miller, M. A.; Moscoso, J. G.; Koster, S.; Gatter, M. G.; Lewis, G. J. Stud. Surf. Sci. Catal. 2007, 170, 347. (2) (a) Miller, M. A.; Lewis, G. J.; Moscoso, J. G.; Koster, S.; Modica, F.; Gatter, M. G.; Nemeth, L. T. Stud. 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