Utilizing ionic liquids as additives for oil property modulation

Abstract

Ionic liquids are assessed as chemical additives to modulate physical properties of oils. Rheometry, differential scanning calorimetry, thermogravimetric analysis and microscopy are used to investigate the effect of ionic liquids on oil properties. The measured maximum apparent viscosity value of Model Oil A increases by 178.7% in the presence of 1 wt% 1-butyl-3-methylimidazolium chloride. Similarly, the value increases in the presence of other conventional ionic liquids. However, the dispersed property of ILs in Model Oil A is not as good as expected. Thus, dispersant D-IL-202 is utilized to make ionic liquids dispersed completely in Model Oil A and form Model Oil B. The gel strength and maximum measured apparent viscosity of Model Oil B increase by 477.4%, 352.4% respectively in the presence of 1 wt% 1-butyl-3-methylimidazolium chloride. Wax crystals precipitate at temperature below wax appearance temperature. The melting point of 1-butyl-3-methylimidazolium chloride is higher than wax appearance temperature. Therefore, during the gelation process, the precipitated crystals of 1-butyl-3-methylimidazolium chloride may serve as nuclei and enhance wax crystal nucleation, precipitation and growth. In addition, the charges of 1-butyl-3-methylimidazolium chloride may make the precipitated wax crystals form a charge-stabilized colloids system. Thus, strong and stable crystal networks form during the gelation process. 1-Butyl-3-methylimidazolium chloride can be utilized as a wax promoter additive for wax separation from waxy oils in the oil industry. Thermogravimetric analysis shows 1-butyl-3-methylimidazolium chloride does not influence the decomposition temperatures of wax and asphaltene. However, the decomposition temperature of 1-butyl-3-methylimidazolium chloride increases in the presence of wax and decreases in the presence of asphaltene. Furthermore, micrographs results show 1-butyl-3-methylimidazolium chloride enhances wax precipitation to make long wax crystals form. In summary, the conventional ionic liquids used in this work can enhance the wax precipitation and/or stabilize the wax crystal networks. Thus, these ionic liquids can be utilized as a wax promoter additive for wax separation in the waxy oil industry. In addition, the property and function of ionic liquids can be designed and modified to be utilized as novel additives for oil properties modulation. Therefore, ionic liquids are promising environmentally friendly additives for the oil industry.