Polymeric Sorbents as Energy-Efficient Alternative to Cryogenic Distillation for Light Hydrocarbon Purification

Light hydrocarbons are essential gaseous compounds for fuel, polymer manufacturing, fertilizer production, and so forth. The efficient recovery and purification of these gases are still challenging despite their significant industrial and domestic relevance. They exist in the gaseous state under ambient temperature and pressure and are typically recovered from natural gas streams containing multiple close-boiling-point hydrocarbons. So far, cryogenic distillation is the commonly used method for their separation and purification. It operates based on their boiling-point differences, which amounts to significant energy consumption. To address this limitation, adsorption-based technology is considered an energy-efficient alternative for the purification of light hydrocarbons. To this effect, polymeric sorbents such as porous polymer networks (PPNs) are a potential alternative due to their robustness, stability, and scalability. This review provides an extensive discussion on cryogenic distillation, applications of light hydrocarbons, and progress in light hydrocarbon purification using polymeric sorbents. Additionally, the pore structure, stability, and techno-economic feasibility of the polymeric sorbents were extensively examined, covering current progress, mechanism of guest molecule separation, characterization techniques, and hurdles still encountered. Overall, since their application in light hydrocarbon separation is still an evolving field, this review will facilitate robust designs by providing the necessary know-how and roadmaps needed for advancement.