Mechanistic Modeling of Palmitic Acid Esterification via Heterogeneous Catalysis

Abstract

Biodiesel has emerged as a promising renewable and clean energy alternative to petrodiesel. While biodiesel has traditionally been prepared through homogeneous base catalysis, heterogeneous acid catalysis has been investigated recently due to its ability to convert cheaper but high “free fatty acid” content oils such as waste vegetable oil while decreasing production cost. In this work, the esterification of free fatty acid over sulfated zirconia and activated acidic alumina was studied experimentally in a batch reactor. The models of the reaction over the catalysts were developed in two parts. First, a kinetic study was performed using a deterministic model to develop a suitable kinetic expression, and the related parameters were estimated. Second, a stochastic model was developed as a pseudo-verification of the nature of the reaction at the molecular level. The esterification of palmitic acid obeyed the Eley−Rideal mechanism in which palmitic acid and methanol are adsorbed on the surface for SO4/ZrO2−55...