Solid base catalysts for transesterification of oil with methanol to produce biodiesel

Solid base catalysts used in the transesterification for biodiesel production can simplify the technological processes, especially the separation process of products.By screening metal oxides, calcium oxide was found to be a potential catalyst for the transesterification of rapeseed oil.Impregnating calcium acetate solution onto MgO carrier and calcining the impregnated sample obtained a CaO/MgO catalyst containing 16.5%(mass) of calcium oxide, which exhibited a high activity in the transesterification reaction.By using this catalyst, under the condition of 64.5℃, a methanol/oil molar ratio of 18∶1 and a catalyst dosage of 2%, oil conversion reached 92% in 3.5 h, which was close to the oil conversion using the traditional NaOH.Furthermore, the solid catalysts obtained were characterized with XRD, AAS, XPS and CO2-TPD.The results showed that the basicity of the catalysts greatly affected their activities.Properly selecting the carrier, precursor and Ca-loading could increase the strong basic sites, and therefore increase their catalytic activity.