Asymmetrical polyimide membranes with programmable polymer chain architectures for liquid hydrocarbon fractionation

Area of Science:

• Materials Science
• Chemical Engineering
• Polymer Chemistry

Background:

• Conventional liquid hydrocarbon fractionation uses energy-intensive distillation.
• Organic solvent reverse osmosis (OSRO) is an energy-efficient alternative.
• Developing OSRO membranes with tailored molecular differentiation for complex hydrocarbons remains a challenge.

Purpose of the Study:

• To engineer diverse fluorinated polyimide membranes with programmable polymer chain architectures for efficient hydrocarbon separation.
• To achieve tunable permselectivity for hydrocarbons with less than 40 carbon atoms.
• To demonstrate the application of these membranes in hydrocarbon mixture fractionation.

Main Methods:

• Stoichiometry-controlled polycondensation to regulate polyimide chain packing and microporosity.
• Molecular simulations to verify polymer structure and properties.
• Solution casting and thermal annealing to prepare asymmetrical membranes with defect-free thin layers (100-250 nm).

Main Results:

• Successfully synthesized fluorinated polyimides with finely regulated chain packing and microporosity.
• Fabricated defect-free asymmetrical membranes exhibiting tunable permselectivity for hydrocarbons.
• Demonstrated a two-stage cascade process for kerosene-paraffin mixture fractionation, enriching C10-C13 hydrocarbons from 50% to 97%.

Conclusions:

• The developed polyimide membranes possess on-demand molecular discrimination capabilities for hydrocarbon separation.
• These membranes offer a promising, energy-efficient alternative to distillation for hydrocarbon fractionation.
• The study highlights the potential of programmable polymer architectures in advanced membrane technology.