2024 Theses Doctoral

Multiscale Design of Hybrid Sorbent Materials for Carbon Capture and Enhanced Sorbent Regeneration via Non-Thermal Energy Transfer

Lee, Ga Hyun

This dissertation explores the development and optimization of Metal-Organic Frameworks (MOFs) and Nanoparticle Organic Hybrid Materials (NOHMs) for efficient CO₂ capture and investigates enhanced sorbent regeneration using a non-thermal transfer. Chapter 2 introduces the versatility and challenges of MOFs, including their structural adaptability and issues with hydrostability, highlighting the need for water-resistant modifications or coatings to maintain functionality in humid conditions. Chapter 3 and 4 focus on advancements in MOF design for CO₂ capture and the synthesis of encapsulated MOFs with enhanced durability against moisture, using HKUST-1 integrated with hydrophobic polymer PTMSP as an example to demonstrate its potential despite challenges in optimizing CO₂ sorption efficiency when exposed to water. Chapter 5 explores NOHMs, particularly ionically tethered polyethylenimine (NIPEI), for creating air-filter-like fiber mat systems with significant CO sorption capabilities, even under low CO₂ concentrations and humid conditions, suggesting further material and design optimization for industrial applications.

Chapter 6 presents a modeling study on gas transport behaviors within NOHM-polymer interfaces, utilizing Molecular Dynamics (MD) simulations to enhance our understanding of CO₂ sorption dynamics, pointing towards the importance of ion diffusion rates and the distribution of gas molecules for improved capture efficiency. Chapter 7 delves into CO₂ desorption techniques, comparing microwave radiation to conventional thermal heating, showing the efficiency and energy-saving benefits of microwave regeneration, especially when incorporating Fe₃O₄ magnetite into NOHMs. This chapter also stresses the necessity of innovative reactor designs to ensure uniform heating and address technical challenges like nanoscale temperature measurement and uneven heat distribution.

Chapter 8 extends the discussion to future research directions, emphasizing the potential of NOHMs for CO₂ capture and conversion, the exploration of their electrochemical performance, and the need for understanding CO₂ transport mechanisms for enhanced conversion efficiency. It calls for comprehensive evaluations of sorbents in terms of stability, kinetics, capacity, selectivity, and cost-effectiveness, alongside advancements in microwave regeneration technology to overcome current limitations in sorbent heating efficiency.

Overall, this dissertation underscores the ongoing need for innovative solutions to improve CO₂ capture technologies, highlighting the promise of MOFs and NOHMs in addressing climate change challenges through scalable carbon capture, utilization, and storage (CCUS) applications.