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

Author(s)

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

• Document type: Journal article
• Source: CATALYSIS TODAY; v. 344, p. 7-pg., 2020-03-15.

Abstract

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)

• FAPESP's process: 16/12752-5 - Study of MgO formation with hierarchical pores system as a catalyst for ethanol steam reforming
• Grantee: Luiz Gustavo Possato
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 10/01449-3 - Development of porous heterogeneous catalysts for the conversion of renewable feedstocks
• Grantee: Leandro Pierroni Martins
• Support Opportunities: Research Grants - Young Investigators Grants