Synthesis and structure of polymorph B of zeolite Beta

[EN] It was found that either polymorph B or polymorph C of zeolite beta can be obtained from the same structure directing agent: 4,4-dimethyl-4-azonia-tricyclo[5.2.2.0(2,6)] undec-8-ene hydroxide. The synthesis occurs through a consecutive process where polymorph B is first formed and then transformed into polymorph C. It is possible to produce a zeolite highly enriched in polymorph B, provided that the transformation of this phase into polymorph C is slowed down up to the point where polymorph C is only detected at trace levels. The structure of polymorph B was determined for the first time by electron crystallography with SAED and HRTEM from areas of unfaulted polymorph B crystals.Financial support from the Spanish Government (Project MAT2006-14274-C02–01) and the EU Commission (TOPCOMBI Project) is gratefully acknowledged. M.M. thanks CSIC for an I3P grant. J.S. is supported by a postdoctoral grant from the Carl Trygger Foundation. The Berzelii Centre EXSELENT is supported by the Swedish Research Council (VR) and the Swedish Governmental Agency for Innovation Systems (VINNOVA).Corma Canós, A.; Moliner Marin, M.; Cantin Sanz, A.; Díaz Cabañas, MJ.; Jorda Moret, JL.; Zhang, D.; Sun, J.... (2008). Synthesis and structure of polymorph B of zeolite Beta. Chemistry of Materials. 20(9):3218-3223. doi:10.1021/cm8002244S3218322320

Catalytic activity of the Al-EMT and AlGa-EMT zeolite

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Synthesis of Zeolites in the Presence of Diquaternary Alkylammonium Ions as Structure-Directing Agents

This paper deals with the synthesis results obtained mostly from pure silica systems in the presence of (CH3)3N+(CH2)nN+(CH3)3 ions (n = 5, 6, 9 or 10) in fluoride media, but also in the presence of (CH3)3N+(CH2)nO(CH2)nN+(CH3)3 ions (n = 2 or 4) in hydroxide or fluoride media. A variety of zeolites form, namely ZSM-48, MTW-type, BEA-type, MFI-type, ITH-type zeolites, but also, in case of pronounced degradation of the template into N(CH3)4+ or N(CH3)3, AST-type, MTN-type and RUT-type materials. The samples are characterized by XRD, SEM, thermal and elementary analyses, 1H liquid NMR (after dissolution of the sample in HF aqueous solution) and solid-state NMR (19F, 13C, 27Al) spectroscopy

Synthesis of the LTA-type AlPO4 in the presence of the diazapolyoxamacrocycle 'Kryptofix 222'

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Synthèse et caractérisation de zéolithe Ga-MCM-22

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Positron and positronium in porous media: zeolites

Correlations between positronium (Ps) production features and positron annihilation (PA) parameters were investigated in various zeolite samples (MFI, mordenite, Na-Y). The contribution of 3[gamma]-annihilation on data registration was closely examined. Long lifetimes up to 135 ns and triplet Ps (o-Ps) fractions up to 30% were found. Even low amounts of adsorbed gases or water drastically change the PA pattern. It is concluded that in addition to the crystallographic free sites, large structural discontinuities also play an important role as they can trap Ps and provide it with vacuum-like survival conditions.http://www.sciencedirect.com/science/article/B6TVT-48KF810-2/1/8430b8c2999ae974e706966d129f1ae

IM-17: a new zeolitic material, synthesis and structure elucidation from electron diffraction ADT data and Rietveld analysis

International audienceThe synthesis and the structure of IM-17, a new germanosilicate with a novel zeolitic topology, prepared hydrothermally with decamethonium as the organic structure directing agent, are reported. The structure of calcined and partially rehydrated IM-17 of chemical formula per unit cell |(H2O)14.4|[Si136.50Ge39.50O352] was solved ab initio using electron diffraction ADT data in the acentric Amm2 (setting Cm2m) space group and refined by the Rietveld method. This new zeolite framework type contains a 3D pore system made of intersecting 12, 10 and 8-ring channels