Hierarchical chabazites synthesized by combining primary and secondary structure-directing agents

Autor(es)

Marins, Natalia Hadler ; Pereira, Elen Maria Feliciano ; Alahakoon, Sandamini H. ; Huang, Yining ; Martins, Leandro

• Tipo de documento: Artigo Científico
• Fonte: Microporous and Mesoporous Materials; v. 346, p. 10-pg., 2022-11-04.

Resumo

Modifying the physical and chemical properties of zeolites by altering the synthesis parameters or using post -synthesis treatments may offer additional properties other than those that make them widely used materials. Remarkably, the chabazite SSZ-13 zeolite possesses a small pore opening that provides access to a large cavity, making the structure suitable for converting methanol to products. Herein, we altered the porosity of SSZ-13 by adding various amounts (2, 4, and 8% in relation to the molar silica content) of dimethyloctadecyl[3-(trime-thoxysilyl)propyl] ammonium (DMOAP) into the reaction mixture. The introduction of DMOAP enabled the formation of the pure chabazite structure without affecting the incorporation of aluminum atoms into the zeolite framework. At the same time, its incorporation led to changes in porosity, increasing the external surface area and creating mesopores without affecting the formation of micropores. Concerning the catalytic conversion of methanol into products at low temperatures (210 degrees C), the additional porosity decreased the methanol to dimethyl ether conversion, indicating that the confinement effect plays an essential role in stabilizing the re-action intermediates. However, at higher temperatures (400 degrees C), the mesopores played an essential role in the methanol to olefins reaction by increasing the catalyst lifetime and the conversion over time due to improved accessibility of methanol to reaction intermediates confined in the micropores. (AU)

• Processo FAPESP: 19/12201-7 - Estruturas de zeólitas selecionadas como suportes para óxidos de metais de transição para conversão seletiva de metano em produtos químicos de valor agregado
• Beneficiário: Natália Hadler Marins
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 18/01258-5 - Novos processos catalíticos e fotocatalíticos para a conversão direta de metano e CO2 em produtos
• Beneficiário: José Maria Correa Bueno
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 20/07265-3 - Síntese de zeólitas hierárquicas mordenita e chabazita e suas propriedades catalíticas
• Beneficiário: Natália Hadler Marins
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Pós-Doutorado
• Processo FAPESP: 19/12486-1 - EMU concedido no processo 2018/01258-5: cromatógrafo a gás
• Beneficiário: Leandro Pierroni Martins
• Modalidade de apoio: Auxílio à Pesquisa - Programa Equipamentos Multiusuários