production of n-butyl levulinate over modified kit-6 catalysts: comparison of the activity of kit-so3h and al-kit-6 catalysts

The catalytic activity of propylsulfonic acid-functionalized mesoporous silica (kit-so3h) was compared to the performance of alumina-incorporated kit-6 (al-kit-6) in the esterification reaction of the biomass-derived levulinic acid with n-butanol. the catalysts were prepared by functionalization of the silica support with propylsulfonic acid (pr-so3h) by post-synthesis grafting using 3-mercaptopropyltrimethoxysilane as a propyl-thiol precursor followed by oxidation. in addition, al-kit-6 was synthesized according to in situ synthesis. catalysts were characterized using various techniques such as xrd, nitrogen adsorption/desorption, sem, tga, icp-oes, ft-ir and elemental analysis. it is evident that increases in catalyst loading, butyl alcohol-to-levulinic acid ratio and reaction temperature significantly enhance the butyl levulinate yield. the reusability and stability of catalysts were evaluated, and it was found that while esterification reaction by kit-so3h compound catalyzed under milder conditions, the stability of al-kit-6 catalyst was better.