Currently, the major concern in production of biodiesel fuel is to exploit for new catalysts with the optimal conditions. In this study, the effect of calcination temperature on the synthesis of 20 mol.% SrO/S-ZrO2 was examined by solvent-free method. Moreover, the ability of the catalyst for esterification reaction of oleic acid with methanol was also assessed. To obtain this objective, x-ray diffraction and infra-red spectroscopy method was employed to characterize the structure of the catalysts. The results of this study reveal that the calcined strontium oxide promoted sulfated zirconia at 500 oC has the highest percentage of tetragonal phases of zirconia. It has also been demonstrated that owing to the high percentage of the tetragonal phases of zirconia and the acidity of the catalyst, conversion of oleic acid to fatty acids methyl esters (i.e., FAME) could be enhanced from 88.36% to 91.13%. Moreover, it has also been shown that 20 mol.% SrO/S-ZrO2 exhibits higher activity in comparison with S-ZrO2 at 500 oC in esterification reaction due to presence more sulfate ions and higher activity of strontium ions.

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