Oil Deasphalting Using Ultrafiltration PAN Membranes

With the development of oil fields, the proportion of the highest-molecular-weight components, asphaltenes, increases in the composition of the extracted raw materials. The propensity of asphaltenes to aggregate causes a number of problems, which makes the task of oil deasphalting relevant. In this work, studies on separation of the asphaltene fraction from oil using PAN membranes are carried out. To decrease the pore size of membranes obtained by a phase inversion method, an additional component, acetone, is introduced into the casting solution. The permeability of the resulting membranes for water is 37.6 ± 1.7 L m⁻² h⁻¹ atm⁻¹ and for toluene, 25.3 ± 1.8 L m⁻² h⁻¹ atm⁻¹, and the pore size is 4.6 ± 0.5 nm. When filtering solutions of oil diluted with toluene (1 g/L), the retention of the membranes for asphaltenes is 73 ± 4%, while it exceeds 95% when the oil content in the solution is over 10 g/L. The parameters of membrane fouling during filtration of solutions of oil in toluene are studied. It is noted that, upon moving from toluene to solutions of oil, the permeability of the membranes decreases tenfold. At the same time, the decrease in permeability is reversible, and when the solution of oil is replaced by a pure solvent, the membrane restores up to 99% of its initial permeability.