(571f) A Green Solvent Incorporated Membrane Contactor Based Process for Energy-Efficient CO2 Capture and Separation

The climate change due to CO₂ emissions has become a profound environmental concern. This will result in catastrophic consequences including temperature rise, sea level rise, flood, drought, and serious damage in ecosystem. In this work, we have developed a novel scalable energy-efficient and cost-effective hollow fiber membrane contactor-based process for highly efficient CO₂ capture and separation achieved by fundamental understanding of a green solvent-based CO₂ capture and separation. An integrated process is developed using a deep eutectic solvent (DES) in a hollow fiber membrane contactor (HFMC) to provide close interfacial interactions and contact between DES and CO₂. DES, typically a mixture of a hydrogen bond acceptor (HBA) and a hydrogen bond donor (HBD) is a low-cost environmentally friendly physical CO₂ sorbent which requires low energy input for CO₂ separation. It was synthesized using choline chloride and urea as the precursors, and was comprehensively characterized using gas sorption isotherm, viscosity, Differential Scanning Calorimetry (DSC), Karl Fischer titration, Nuclear Magnetic Resonance, and Raman spectroscopy measurements. Commercial low-cost polymer hollow fiber membranes (e. g., microporous polypropylene) are identified based on pore structure, surface area, chemical, and thermal compatibility, and mechanical strength. The DES incorporated HFMC system is used to capture and separate CO₂ from N₂. The results showed selective separation of CO₂ while completely rejecting N₂ of flue gas. Although this green solvent has excellent physicochemical properties for high-performance CO₂ separation, the fundamental understanding of the mechanism of separation of CO₂ using DES is limited. Moreover, how the constituent moieties of DES bind CO₂ and their intermolecular and intramolecular interaction is not well known. This work also utilizes the computational tools such as Density Functional Theory (DFT) calculation and molecular dynamics simulations to elucidate the myriad interactions of DES and CO₂ to understand the binding mechanism for identification of the ideal DES with best CO₂ absorption capacity and selectivity over other gases. This research can provide both fundamental insights about physical solvent-based separation process as well as a pathway for its industrial deployment. A major advantage of HFMC-based process is scalability with a potential for large scale industrial deployment for CO₂ capture and separation from various sources including flue gas emitted from power plant.