Effects of zirconia loading in sulfated zirconia/SBA-15 on esterification of palmitic acid with glycerol

Sulfated zirconia supported on SBA-15 (SZSBA-15) catalysts with different zirconia loadings (5-20 wt%) were synthesized using urea hydrolysis method. Effects on the physicochemical properties of the catalysts and activity in selective glycerol esterification with palmitic acid were particularly investigated. Various characterization techniques such as N-2 adsorption-desorption analysis, SEM, TEM, TGA, FTIR, NH3-TPD and acidity measurement by titration were used. Increasing zirconia loading decreased the surface area, pore size and pore volume of the catalysts, but increased the sulfate content and improved the catalyst acidity. Larger surface area was not the major factor in determining the catalyst activity especially in the reaction involving bulky molecules. The reaction was found to be influenced by the amount of active sites presence on the catalyst and also by the dimension of the pores which slightly promoted the shape selective reaction. Among all catalyst, 15SZSBA-15 demonstrated the highest activity with 88% conversion and 44% monopalmitin yield.