K2MgSiO4: A novel K+-trapped biodiesel heterogeneous catalyst produced from serpentinite Mg3Si2O5(OH)4

• Published in: Journal of molecular catalysis. A, Chemical Vol. 422; pp. 258 - 265
• Main Authors: Ballotin, Fabiane Carvalho, Cibaka, Thérèse Ebambi, Ribeiro-Santos, Tatiana A., Santos, Eleonice Moreira, Teixeira, Ana Paula de Carvalho, Lago, Rochel Montero
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-10-2016
• Subjects: Biodiesel; K2MgSiO4; Serpentinite; Biodiesel; Serpentinite; K2MgSiO4
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/j.molcata.2016.02.006

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•A new basic catalyst was produced by the serpentinite impregnation with KOH.•The potassium and thermal treatment of serpentinite leads to a new phase K2MgSiO4.•The material can be used for biodiesel production.
In this study, a new catalyst for biodiesel synthesis, based on K2MgSiO4, was produced from the mineral serpentinite. TG, SEM, XRD, AA, BET analyses showed that serpentinite Mg3Si2O5(OH)4 impregnated with KOH (5,10 and 20wt%), and thermally treated at 500°C, 700 and 900°C, can be converted to the main crystalline phase K2MgSiO4. Analyses by TPD-MS (CO2) and titration suggested the presence of weak/medium basic sites in relatively high concentrations. Biodiesel production using soybean oil (methanol:soybean oil ratio of 1:12, 1:9; 1:6, 60°C) showed yields higher than 95% with catalyst at 10wt%, which can be reused for three consecutive times without significant decrease on the reaction yield. The obtained results are discussed in terms of a new catalytic phase based on K+ ions trapped in the cavities of the MgSiO42− structure containing negatively charged oxygen basic sites.