Abstract Temperature dependency of infrared band intensity for methylene rocking vibration could be used as indication for creation of solid crystals while decreasing temperature. In this work, different experiments were conducted to measure wax appearance temperature, WAT, such as cross polarized microscopy, rheometry and FTIR spectroscopy. Three Iranian crude oils were characterized based on the SARA test and PC-SAFT model was developed to predict WAT. The obtained results by FTIR spectroscopy and PC-SAFT model were in quite agreement. FTIR spectroscopy determined higher WAT values which may be due to its higher sensitivity to smaller wax crystals. Also, the effect of a polymeric crystal modifier (EVA) and an aromatic solvent (toluene) on wax precipitation was investigated. EVA dramatically decreased the pour point of lower waxy crude oils. Toluene dissolved polar compounds such as asphaltene and consequently decreased WAT and pour point. This observation confirmed that asphaltene supports the wax crystallization and its growth.
H. M. Meighani, C. Ghotbi, T. J. Behbahani
Journal of Molecular Liquids