John L. Schlenker

The framework topology of zeolite beta

The tetrahedral framework structure of zeolite beta is disordered along [001]. The disordered beta framework and three simple ordered polytypes are related through layer displacements on 001 planes. Three mutually perpendicular 12-ring channel systems are characteristic of the three ordered polytypes and the disordered beta structure. The proposed framework structures are consistent with the known diffraction, sorption, and cation-exchange properties of zeolite beta.

Framework topology of AIPO4-8: the first 14-ring molecular sieve

The framework topology of AIPO 4 -8, a synthetic aluminophosphate molecular sieve, has been determined via model building followed by DLS-refinement and powder pattern simulation. AIPO 4 -8 has been shown to possess a unidimensional 14-ring channel system with pore dimensions 7.9×8.7 A.

Development of a formation mechanism for M41S materials

1. Summary The influence of surfactant/silica molar ratio(Sur/Si) in M41S syntheses was studied in the simple synthesis system consisting of tetraethylorthosilicate(TEOS), water, and the cetyltrimethylammonium(CTMA) cation at 100°C. As the Sur/Si increased from 0.5 to 2, the siliceous products obtained were identified and could be classified into four separate groups: MCM-4 1(hexagonal), MCM-48(cubic), thermally unstable M4 1 S, and a molecular species, the organic octamer [(CTMA)SiO2, 5]8. One of the thermally unstable structures has been identified as a lamellar phase. These results are consistent with micellar phase transformations that occur at various surfactant concentrations and reinforce the concept that micelle structures serve as templating agents for the formation of M41S type materials.

The framework topology of ZSM-57: A new synthetic zeolite

ZSM-57 is a new zeolitic phase with a novel framework topology: structure code MFS, space group lmm2, a = 7.4510(7)A, b = 14.1711(8)A, c = 18.767(2)A, 18.2T/1000 A3. Although the structure is closely related to ZSM-35 (FER), ZSM-57 has 4-rings lacking in the ferrierite framework. There is a channel system of intersecting 8- and 10-rings. Although the dimensions of the 8-ring (3.5 × 4.8A) channel differ only marginally from ZSM-35, the 10-ring channels (5.1 × 5.8A) are significantly larger than are the analogous channels in ZSM-35 and slightly larger than are the 10-rings in ZSM-5.

Synthesis and characterization of synthetic zeolite ECR-1

Zeolite ECR-1 has been synthesized from a low SiO 2 /Al 2 O 3 reaction mixture in the presence of adamantane-containing diquaternary alkylammonium iodides with the following structures. ECR-1 was first prepared by Vaughan and Strohmaier in 1987 (US Pat. 4,657,748). Their synthesis method used other directing agents in combination with sodium zeolite (aluminosilicate) seeds. Two models with related but distinct framework topologies have been proposed as possible solutions of the ECR-1 structure. Our work has established that one of these, ECR-1 B, can be rejected as a structural solution. The remaining model, ECR-1A, described by Leonowicz and Vaughan ( Nature 1987, 329 819) is probably the correct framework of ECR-1.