Traditionally, the deasphalting process was used to process vacuum residue associated with the production of valuable raw materials. Currently, solvent deasphalting is also used in the refining of heavy oils and petroleum residues by removing undesirable components or impurities to facilitate and/or enable subsequent transportation and/or processing through thermal and catalytic cracking processes. The use of membrane separation has the potential to significantly reduce the cost and energy consumption of the deasphalting process.

In this work, PAN membranes with ultra-low pore size were obtained for asphaltenes removal from oil. Addition of acetone to casting solution possess to obtain membranes with a molecular weight cut-off value (MWCO) of 1800 g/mol. These membranes made it possible to effectively (up to 99%) remove asphaltenes from oil/toluene solutions where concentration of asphaltenes was low. In case oil with high asphaltenes content optimal filtration characteristics were obtained with PAN membranes with pore size 21 nm. Such membranes retained from undiluted oil 99.9% of components with molecular weight higher than 590 g/mol when components with a molecular weight of less than 324 g/mol pass freely.

Modification of obtained membranes by addition of carbon particles demonstrated positive effect on membrane permeance. Addition of 1% nanodiamonds increases oil flux through membrane by 3 times. It is also shows that addition of the nanodiamonds reduces overall membrane fouling. 

This work was funded by the Russian Science Foundation (Project no. 24-29-00851).