On the porous silicate HPM-5
HPM-5, a porous aluminosilicate with an intricate and so far unsolved structure, has been synthesized by using 1,2,3-trimethylimidazolium in hydroxide medium in the absence of fluoride anions. It consistently displays an ill-defined XRD pattern with broad and overlapped reflections and contains a la...
| Autores: | , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2017 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/188348 |
| Acceso en línea: | http://hdl.handle.net/10261/188348 |
| Access Level: | acceso abierto |
| Palabra clave: | Zeolites Silicates Microporous materials Nanostructures Zeolite analogues |
| Sumario: | HPM-5, a porous aluminosilicate with an intricate and so far unsolved structure, has been synthesized by using 1,2,3-trimethylimidazolium in hydroxide medium in the absence of fluoride anions. It consistently displays an ill-defined XRD pattern with broad and overlapped reflections and contains a large concentration of defects, as evidenced by IR and Si MAS NMR spectroscopy. H MAS NMR spectroscopy confirmed the existence of highly deshielded protons (δ = –11.6 ppm) assigned to hydrogen atoms in relatively strong Si–O–H···O–Si hydrogen bonds (O···O distance ≈ 2.64 Å) The calcined material shows limited microporosity (0.07–0.09 cm g). The results of a high-resolution transmission electron microscopy study suggest HPM-5 may be far more complicated than “standard” layered zeolites and may consist of low-density layers profusely decorated by holes. The resulting lace-like layers may be too unstable to withstand reactions characteristic of more conventional layered materials (both delamination and expansion by silylation); although the derivatives show an increase in the specific surface area, the layers are apparently disassembled and, at most, only ribbons remain. |
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