Purification of phet wax using crystallization and supercritical carbon dioxide extraction

Abstract

Wax deposition problems found during crude oil production transportation can cost millions of dollars a year. In Thailand, the wax deposition in transportation wagons is removed and then disposed of, and the company loses the opportunity to profit from the wax. To enable value addition to the wax, separating and de-oiling it using several processes can be done. The sludge wax was first characterized by simulation distillation gas chromatograph (SimDist-GC). Then, crystallization and supercritical fluid CO2 extraction methods were investigayed to separate and purify the wax. Toluene, methyl ethyl ketone (MEK), and a toluene/MEK mixture were used as solvents and the effects of solvent type, solvent amount (solvent to wax ratio), and solvent composition, as well as important extraction parameters, such as pressure, extraction time, and CO2 flow rate in the supercritical fluid CO2 extraction, were also investigated. The results showed that a purified by using crystallization with the mixed solvent in a ratio of 1:1 had the highest purity (over 98%), while those obtained from the supercritical fluid CO2 extraction had lower purity (over 95%). Supercritical fluid CO2 extraction, however, appeared to be an attractive option for purification of wax without the use of a liquid-based solvent.