Ti-ATMP catalyzed esterification of levulinic acid to synthesize butyl ester

Abstract

In the present work, a hybrid catalytic material of the class of tetravalent metal acid (TMA) salts has been synthesized by the sol–gel method, wherein solution of titanium tetrachloride is allowed to react with claw-type organic phosphonic acid, amino tris methylenephosphonic acid (ATMP) under appropriate reaction conditions of pH, temperature, time and ageing period. The resultant hybrid material (Ti-ATMP) was found to possess proton donating behaviour, and hence it was thought of interest to use it as solid acid catalyst to perform catalysed esterification reaction of biomass-derived levulinic acid with n-butanol to synthesize n-butyl levulinate. Various process parameters such as catalyst concentration % (X1), LA:n–butanol molar ratio (X2) and reaction time (min) (X3) were optimized by response surface methodology (RSM), using the Box–Behnken Design (BBD). Analysis of variance was performed in order to check the suitability of the quadratic model. The catalytic reusability study has been performed in order to have an idea about feasibility of its reuse. Ti- ATMP catalyst was found efficient and promising with satisfactory yields and excellent reusability. The results clearly indicate its potentiality as solid acid catalyst to catalyse other organic transformations.