Emulsion-mediated synthesis of hierarchical mesoporousmacroporous Al-Mg hydrotalcites

Autor(es)

Petrolini, Davi D. ; Urquieta-Gonzalez, Ernesto A. ; Pulcinelli, Sandra H. ; Santilli, Celso V. ; Martins, Leandro

• Tipo de documento: Artigo Científico
• Fonte: Microporous and Mesoporous Materials; v. 240, p. 149-158, MAR 1 2017.
• Citações Web of Science: 6

Resumo

A new sol-gel method mediated by the use of paraffin emulsions is presented for the synthesis of hierarchical mesoporous-macroporous Al-Mg hydrotalcites. Prior to the synthesis, the construction of ternary diagrams for paraffin/surfactant/ethanol helped to identify the most suitable compositional synthesis domain. Two distinct regions, denoted L1 (transparent microemulsion) and L2 (opaque emulsion) were identified for low and high concentrations of paraffins, respectively. The ternary diagrams revealed some features: i) n-hexane (C6) had the smallest L2 region; ii) the high viscosity of n-octadecane (C18) did not allow control of phase separation, and iii) the most suitable paraffin for the use as the emulsifier was the intermediate-sized n-dodecane (C12). The use of paraffin in concentrations included in the Ll region did not contribute to the creation of pores, but the emulsion templating in the L2 region led to hierarchical porous hydrotalcites when were calcined up to 250 C-circle having enhanced textural properties and presenting mesopores and macropores with mean sizes of 0.02 and 1 mu m, respectively. The slit-like shaped mesopores were caused by the partial exfoliation of hydrotalcite layers unordered packed around the emulsion droplets, while the macropores arose from voids left by the droplets after thermal treatment. The singular textural properties of the studied Al-Mg hierarchical porous hydrotalcites turns the emulsion mediated-synthesis a potential method to obtain more efficient catalysts to be used in process involving bulky molecules. (C) 2016 Elsevier Inc. All rights reserved. (AU)

• Processo FAPESP: 15/05321-5 - Síntese de catalisadores com poros estruturados derivados da hidrotalcita por uso combinado de química sol-gel, tensoativos e emulsão
• Beneficiário: Davi Domingos Petrolini
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 13/01328-0 - Metodologias avançadas de síntese de zeólitas hierárquicas e caracterização por diferentes técnicas para melhor utilização de materiais microporosos em catálise heterogênea
• Beneficiário: Leandro Pierroni Martins
• Modalidade de apoio: Auxílio à Pesquisa - Regular