Biodiesel production from waste frying oils over lime catalysts

Puna, Jaime Filipe Borges; Correia, Maria Joana Neiva; Dias, Ana Paula Soares; Gomes, João Fernando Pereira; Bordado, João; João Carlos Moura

Key information

Authors:

Puna, Jaime Filipe Borges; Correia, Maria Joana Neiva (Maria Joana Castelo-Branco de Assis Teixeira Neiva Correia); Dias, Ana Paula Soares (Ana Paula Vieira Soares Pereira Dias); Gomes, João Fernando Pereira (João Fernando Pereira Gomes); Bordado, João (Jaime Filipe Borges Puna); João Carlos Moura (João Carlos Moura Bordado)

Published in

08/01/2013

Abstract

Biodiesel production from semi-refined oils (SRO) and waste frying oils (WFO) was studied using commercial CaO as heterogeneous catalyst. The methanolysis tests were carried out in mild reaction conditions (62 A degrees C, atmospheric pressure). With such conditions, SRO (soybean and rapeseed) allowed to produce a biodiesel containing 97-98 % of methyl esters (FAME), whereas WFO only provided 86-87 % of FAME. The lower FAME yield for WFO oil is ascribable to the partial neutralization of the catalyst by free fatty acids. Also, soaps formation from the WFO oil reduced the weight yield of the oil phase (containing FAME) obtained and increased the MONG content of the glycerin phase. The catalysts stability tests showed high stability even when WFO oil was processed. Catalytic tests performed with blends of WFO/semi-refined oils showed blending as a good strategy to process low value raw oils with minor decay of the catalyst performance. Both WFO and semi-refined oils showed S-shape kinetics curves thus discarding significant differences of the reaction mechanisms.