Purification of Wax Additives

Ethoxylated waxes and high molecular weight alcohols can be synthesised from synthetic waxes. The conversions in these syntheses are generally low. A purification process is thus required to ensure good utilization of the reagents and a high purity of the products. Due to the fact that these components are not stable at high temperatures, conventional separation methods are not suitable. Supercritical fluids may offer an attractive method for the purification of these products without the risk of thermal decomposition. In this work the aim was to develop a countercurrent supercritical extraction process that can be used to concentrate the ethoxylated waxes to a high value products and to produce a concentrated stream of intermediates and reagents that can be recycled to the synthesis reactor. Phase equilibrium studies have been conducted on paraffins, high molecular weight alcohols and ethoxylated waxes to scan the ability of various solvents to produce the desired products. Propane may prove to be a very good solvent for this separation. A conceptual flowsheet incorporating heat and work integration is proposed. A pilot plant program was started to test the process concepts and to produce products for customer evaluation.