Methods for the Separation of Acylated Surfactant Precursors from Fatty Acids

Abstract

A widely used commercial surfactant, linear alkyl-benzene sulfonate surfactant (LAS), is produced from fossil fuel molecules and requires the incorporation of chelating agents such as metal chelants, increasing complexity and cost. Bio-renewable and biomass-derived oleo-furan surfactants allow replacing current commercial surfactants. One of the major precursors for oleofuran surfactants is alkyl furan ketone (AFK), which is produced from the indirect acylation of anhydride and furanic substrate. Post-indirect acylation products of AFK and fatty acid (FA) byproducts form a eutectic homogenous mixture due to their similar physical properties. Multiple steps of cooling crystallization using 75 wt% methanol as a solvent is the current purification method for Sironix. This is not an ideal separation method due to its succession of steps and poor atom efficiency resulting environmentally unfriendly approach. There are many proposed ways of separating eutectic-forming mixtures such as controlling the nucleation and seeding the crystal, but an efficient, simple and eco-friendly separating approach is still in search for the industry-scale mixtures. Therefore, a better separating method for AFK and FA is needed. In this project, different methods to purify oleofuran surfactant precursor, alkyl furan ketone has experimented with using the information of binary-phase diagrams and Differential Scanning Calorimetry experiments. As a result of this project, a combination of esterification of fatty acid with cooling crystallization was proposed as a possible better separation method.