Synthesis, characterization and reactivity of Lewis acid/surfactant cerium trisdodecylsulfate catalyst for transesterification and esterification reactions

This article reports the synthesis, characterization and application of cerium(III) trisdodecylsulfate trihydrate (Ce[OSO3C12H25](3)center dot 3H(2)O) as a Lewis acid-surfactant-combined catalyst for the production of alkyl esters by solvent-free transesterification and esterification reactions. The new material presents a bilayer lamellar arrangement with an interplanar spacing of d(001) = 3.76 nm, and the dodecylsulfate headgroup in a C-2v symmetry. The reaction of soybean oil and oleic acid with light alcohols (methanol and ethanol) was used as model reactions and high catalytic activity (TOF = 57.4 mol h(-1) mol(cat)(-1)) was observed. The catalyst converted the used feedstocks to esters in less than 4 h with yields greater than 95%. In addition, it can be used to produce biofuels from unrefined and waste oils in which both triacylglyceride and free fatty acid molecules are present. After reaction, the recovered catalyst maintained its activity (>= 95%) for three cycles. The catalyst was characterized by elemental analysis, X-ray powder diffraction (XRD), thermal analysis (thermogravimetry (TG)/derivative thermogravimetry (DTG)/differential thermal analysis (DTA)), pyridine adsorption, and spectroscopic analysis (FTIR and NMR). (C) 2008 Elsevier B.V. All rights reserved.