Synthesis of Biodiesel Using Microwave Absorption Catalysts

Abstract

To enhance the synthesis process for biodiesel (fatty acid methyl ester, FAME), microwave absorption solid acid catalysts were used for transesterification under microwave radiation. The H 2 SO 4 /C catalyst was prepared by an impregnation method. The surface areas of active carbon and H 2 SO 4 /C were measured by the BET method. Synthesis reactions were carried out under different conditions using castor oil and methanol as the feedstock. The amounts of FAME in the product were analyzed by high-performance liquid chromatography. Experimental results showed that the microwave radiation exhibited a notable enhanced effect for transesterification by using the microwave absorption solid acid catalysts (H 2 SO 4 /C) compared with that of the conventional heating method. When the transesterification was carried out at 338 K, with 12:1 molar ratio of methanol to castor oil, 50 wt % loading amounts of H 2 SO 4 and 5 wt % of catalyst to castor oil, after 60 min the yield of FAME 94 wt % was obtained. This method can also be used in the case of castor oil with high free fatty acid.

Transesterification of castor oil usingMgO/SiO2 catalyst and coconutoilas co-reactant

“…Many studies reported that compared to coconut oil, transesterification of castor oil requires higher temperature 10 and higher methanol to oil ratio [11][12] . In an attempt to circumvent these problems, in this current study transesterification of castor oil was carried out using coconut oil as coreactant.…”

Production of Biodiesel from Coconut Oil Using Microwave: Effect of Some Parameters on Transesterification Reaction by NaOH Catalyst

“…In practice a higher molar ratio is needed for the reaction, because the transesterification reaction is reversible. Furthermore, biodiesel and glycerol are miscible due to the use of excess methanol [13,14]. However methanol is strong medium for absorbing microwaves, and thus the excess methanol may absorb microwave energy and reduce the microwave power [9].…”

Alternative Methods for Fatty Acid Alkyl-Esters Production: Microwaves, Radio-Frequency and Ultrasound

“…Since the reaction is reversible, excess alcohol is used to shift the equilibrium to the product side (Fangrui and Milford, 1999). Under Transesterification reaction with alcohol the first step is the conversion of triglycerides to diglycerides, which is followed by the subsequent conversion of higher glycerides to lower glycerides and then to glycerol, yielding one methyl ester molecule from each glyceride at each step (Hideki et al, 2001 Several examples of microwave irradiated transesterification methods have been reported using homogenous alkali catalyst Azcan and Danisman, 2008), acid catalyst (Mazo and Rios, 2010a) and heterogeneous alkali catalyst , heterogeneous acid catalyst (Yuan et al, 2009) and enzymatic . Microwave synthesis is not easily scalable from laboratory small-scale synthesis to industrial multi kilogram production.…”