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Article

Biodiesel Processing Using Sodium and Potassium Geopolymer Powders as Heterogeneous Catalysts

1
Department of Industrial Engineering, University of Padova, via Marzolo 9, 35131 Padova, Italy
2
Course of Chemical Engineering, University of Ribeirão Preto (UNAERP), 14096-900 Ribeirão Preto, São Paulo, Brazil
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Institute of Chemistry, Center for Monitoring and Research of the Quality of Fuels, Biofuels, Crude Oil and Derivatives–CEMPEQC, São Paulo State University (UNESP), 14800-900 Araraquara, São Paulo, Brazil
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Mato Grosso Federal Institute of Education, Science and Technology-Campus Cuiabá, Rua Profa. Zulmira Canavarros, 95, Centro, 78005-200 Cuiabá, Mato Grosso, Brazil
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Department of Materials Science and Engineering, The Pennsylvania State University, University Park, State College, PA 16802, USA
*
Author to whom correspondence should be addressed.
Academic Editor: Sergio Navalon
Molecules 2020, 25(12), 2839; https://doi.org/10.3390/molecules25122839
Received: 22 May 2020 / Revised: 11 June 2020 / Accepted: 17 June 2020 / Published: 19 June 2020
(This article belongs to the Special Issue Advances in Alkali-Activated Materials)
This work investigates the catalytic activity of geopolymers produced using two different alkali components (sodium or potassium) and four treatment temperatures (110 to 700 °C) for the methyl transesterification of soybean oil. The geopolymers were prepared with metakaolin as an aluminosilicate source and alkaline activating solutions containing either sodium or potassium in the same molar oxide proportions. The potassium-based formulation displayed a higher specific surface area and lower average pore size (28.64–62.54 m²/g; 9 nm) than the sodium formulation (6.34–32.62 m²/g; 17 nm). The reduction in specific surface area (SSA) after the heat treatment was more severe for the sodium formulation due to the higher thermal shrinkage. The catalytic activity of the geopolymer powders was compared under the same reactional conditions (70–75 °C, 150% methanol excess, 4 h reaction) and same weight amounts (3% to oil). The differences in performance were attributed to the influences of sodium and potassium on the geopolymerization process and to the accessibility of the reactants to the catalytic sites. The Na-based geopolymers performed better, with FAME contents in the biodiesel phase of 85.1% and 89.9% for samples treated at 500 and 300 °C, respectively. These results are competitive in comparison with most heterogeneous base catalysts reported in the literature, considering the very mild conditions of temperature, excess methanol and catalyst amount and the short time spent in reactions. View Full-Text
Keywords: heterogeneous catalyst; biodiesel; geopolymer; alkali; transesterification heterogeneous catalyst; biodiesel; geopolymer; alkali; transesterification
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MDPI and ACS Style

Botti, R.F.; Innocentini, M.D.M.; Faleiros, T.A.; Mello, M.F.; Flumignan, D.L.; Santos, L.K.; Franchin, G.; Colombo, P. Biodiesel Processing Using Sodium and Potassium Geopolymer Powders as Heterogeneous Catalysts. Molecules 2020, 25, 2839. https://doi.org/10.3390/molecules25122839

AMA Style

Botti RF, Innocentini MDM, Faleiros TA, Mello MF, Flumignan DL, Santos LK, Franchin G, Colombo P. Biodiesel Processing Using Sodium and Potassium Geopolymer Powders as Heterogeneous Catalysts. Molecules. 2020; 25(12):2839. https://doi.org/10.3390/molecules25122839

Chicago/Turabian Style

Botti, Renata F., Murilo D.M. Innocentini, Thais A. Faleiros, Murilo F. Mello, Danilo L. Flumignan, Leticia K. Santos, Giorgia Franchin, and Paolo Colombo. 2020. "Biodiesel Processing Using Sodium and Potassium Geopolymer Powders as Heterogeneous Catalysts" Molecules 25, no. 12: 2839. https://doi.org/10.3390/molecules25122839

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