Controlling the porosity and crystallinity of MgO catalysts by addition of surfactant in the sol-gel synthesis

Autor(es)

Possato, Luiz G. ; Pereira, Elen ; Goncalves, Rosembergue G. L. ; Pulcinelli, Sandra H. ; Martins, Leandro ; Santilli, Celso V.

• Tipo de documento: Artigo Científico
• Fonte: CATALYSIS TODAY; v. 344, p. 7-pg., 2020-03-15.

Resumo

This study presents an easy route to induce pore formation, increase the specific surface area and control the crystallite size of magnesium oxides obtained using the sol-gel method with addition of Pluronic P123 surfactant. The structural characteristics of the materials were evaluated using X-ray diffraction, N-2 physisorption isotherms, mercury intrusion porosimetry, scanning electron microscopy and CO2 temperature programmed desorption. The catalytic properties were assessed using the Knoevenagel condensation reaction. The results showed a systematic decrease of the magnesium oxide crystallinity with increased concentration of the surfactant used in the synthesis. This was associated with increase of the magnesium oxide BET area from 2 m(2)/g to over 50 m(2)/g, as well as the formation of pores in the macropore region, as confirmed by microscopy images. In addition, the surface modification resulted in CO2 chemisorption increasing from 378 mu mol/g, for the pristine MgO sample, to 1529 mu mol/g, for the porous sample, accompanied by an increase in the concentration of strong basic sites. The most porous sample presented the highest catalytic activity in the Knoevenagel condensation reaction. (AU)

• Processo FAPESP: 13/50023-7 - Combinação de técnicas espectrópicas resolvidas no tempo aplicadas ao estudo estrutural de catalisadores com porosidade hierárquica
• Beneficiário: Leandro Pierroni Martins
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 16/12752-5 - Estudo da formação de MgO com sistema hierárquico de poros como catalisadores para reforma a vapor do etanol
• Beneficiário: Luiz Gustavo Possato
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 10/01449-3 - Desenvolvimento de catalisadores heterogêneos porosos para a conversão de matérias-primas renováveis
• Beneficiário: Leandro Pierroni Martins
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores