Effect of preparation conditions on structure and activity of sodium-impregnated oyster shell catalysts for transesterification

Abstract

The catalyst preparation technique plays a significant role in its activity and durability. The present research investigated sodium hydroxide and sodium chloride as the precursor chemicals for impregnation on waste oyster shells that were tested as heterogeneous base catalysts for transesterification of soybean oil. Effects of precursor concentration and calcination temperature on the surface structure and the activity of the catalysts were studied via the one-factor-at-a-time method. The optimal impregnation concentrations of sodium hydroxide and sodium chloride were determined to be 6 mol/L and 2.43 mol/L, respectively. The optimal calcination temperature was determined to be 800°C for both sodium hydroxide and sodium chloride-impregnated catalysts. Analyses of the catalysts via X-ray Diffraction and X-ray photoelectron spectroscopy indicated that different active species were formed on the surface depending on the calcination temperature. Results obtained from this study could be used to fine-tune the procedure for the synthesis of transesterification catalysts from aquatic animal shells.