Accordion-like effect of flexible organic structure-directing agents in the synthesis of ferrierite zeolite

Autor(es)

Almeida, Ramon K. S. ^{[1, 2, 3]} ; Perez-Pariente, Joaquin ^[1] ; Gomez-Hortiguela, Luis ^[1]

Afiliação do(s) autor(es)

^[1] CSIC, ICP, C Marie Curie 2, Madrid 28049 - Spain

^[2] Univ Estadual Campinas, Inst Chem, Rua Monteiro Lobato 270, BR-13084861 Campinas, SP - Brazil

^[3] Univ Fed Rural Pernambuco, Acad Unit Serra Talhada, UAST UFRPE, Av Gregorio Ferraz Nogueira S-N, BR-56909535 Serra Talhada, PE - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Microporous and Mesoporous Materials; v. 300, JUN 15 2020.
• Citações Web of Science: 0

Resumo

Ferrierite zeolite was synthesized by a co-structure-directing route using a highly flexible diquaternary ammonium cation (N,N'-bis-triethylpentanediyldiammonium) as a structure directing agent in combination with tetramethylammonium as a small co-structure-directing agent. Strong alterations of the C-13 NMR bands of the bulky organic dication upon confinement within the ferrierite framework suggest a change of conformation driven by host-guest interactions. A combination of molecular mechanics and DFT calculations of the theoretical C-13 NMR chemical shifts allowed to explain the observed differences in the NMR bands of the dication in solution and when hosted in ferrierite: upon confinement, the flexible dication needs to squeeze through the flexible pentyl chain which locates along the 10 MR ferrierite channels in order to host the two bulky triethyl ammonium groups in adjacent intersections with 8 MR channels. Our work suggests that highly flexible cations, usually considered as less convenient organic structure-directing agents because of low specificity, have the advantage of being able to properly fit with different zeolite cell dimensions through an accordion-like effect by squeezing or stretching their flexible chains. (AU)

• Processo FAPESP: 14/10609-5 - Influência dos agentes direcionadores de estrutura na distribuição dos átomos de alumínio do zeolito mordenita e em suas aplicações catalíticas
• Beneficiário: Ramon Kenned de Sousa Almeida
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Pós-Doutorado