Calcium zincate derived heterogeneous catalyst for biodiesel production by ethanolysis

The transesterification reaction of sunflower oil with ethanol to produce fatty acid ethyl esters (FAEEs) was studied by using calcined calcium zincate as solid base catalyst. The effect of experimental parameters, such as catalyst loading, ethanol:oil molar ratio, free fatty acid and water contents, and stability in the ethanolysis of sunflower oil in the presence of calcium zincate thermally treated at temperatures as low as 400 °C are reported. Thus, by using a 3 wt.% of catalyst at 78 °C, FAEE yields higher than 95 wt.% after 3 h of reaction time, can be reached. The addition of FFA (until 1.1° of acidity) does not affect the catalytic activity, with yields values higher than 95 wt.%, but water brings about a negative effect. However, the catalyst has demonstrated to be less resistant to the reutilization in the ethanolysis process due to the leaching of calcium species, but addition of sodium carbonate to the catalyst before the catalytic process allows obtaining, after washing with water, a biodiesel with concentrations of Ca and Na lower than 5 ppm.