(2h) A Facile Structural Engineering of Metal-Organic Frameworks for Enhanced Gas Separation Performance

In our daily lives, we encounter numerous chemical products that heavily rely on hydrocarbons as their main ingredients. The production of these hydrocarbons involves energy-intensive separation processes. These chemical separation methods, predominantly based on thermally-driven processes, consume a substantial amount of energy, accounting for approximately 10-15% of the world's total energy consumption. To address this energy challenge, membrane separation technology has emerged as an appealing alternative to conventional, energy-intensive separation processes. Membrane-based separation offers significant advantages, such as high energy efficiency and a compact footprint.

Among the various types of membrane materials available, polymeric membranes have gained widespread acceptance in diverse gas separation applications due to their excellent processability and low material cost. However, polymeric membranes are not without their limitations. They encounter certain drawbacks that hinder their overall performance. These limitations include reaching a separation performance limit, experiencing permeability loss due to physical aging, and suffering selectivity loss induced by plasticization. Overcoming these drawbacks is of paramount importance to further enhance the efficiency and reliability of polymeric membrane-based separation processes. By addressing these limitations, we can unlock the full potential of polymeric membranes and pave the way for more sustainable and energy-efficient separation technologies.

From this perspective, my research interests lie in developing Mixed Matrix Membranes (MMMs), which incorporate nanofillers uniformly dispersed within polymeric membranes. MMMs have garnered significant attention as a promising platform due to their potential scalability and excellent molecular size/shape-selective properties. However, for their widespread industrial application, several technical challenges need to be addressed, including fine-tuning the molecular structures and suppressing the formation of interfacial voids between the polymer matrix and nanofillers.

Zeolitic imidazolate frameworks (ZIFs), porous coordination polymers constructed from zinc (or cobalt) metal ions and organic ligands, have emerged as attractive candidates for gas separations. The current study aims to engineer the desired molecular structure of ZIF nanofillers to enhance gas separation performance. A facile defect engineering strategy is proposed to suppress the formation of non-selective interfacial voids and enhance the molecular sieving behavior of [Zn-alkyl amine] and [Zn-functional ligand] coordination within the ZIF framework. Moreover, the molecular structure of ZIFs can be finely tuned either through in-situ synthesis or post-synthetic modification (PSM) to achieve excellent separation performance, such as for C₃H₆/C₃H₈ or CO₂/light-gas separation.

While a significant number of flat-sheet MMMs have been reported for gas separation, there is a scarcity of research on asymmetric mixed matrix hollow fiber membranes (MMHFMs). The conversion of flat sheet MMMs, especially those with a high concentration of nanofillers, into hollow fiber configurations is challenging despite its desirability for large-scale industrial applications. In this presentation, we demonstrate a systematic approach for fabricating defect-free MMHFMs with a high concentration of ZIFs, specifically targeting efficient CO₂ separation using a dip coating process. Furthermore, the impact of different process variables on the structure of the selective layer is investigated, and simulation analysis for the dual-stage CO₂ capture process is validated. The findings of this study contribute to the development of highly concentrated ZIF-incorporated MMHFMs, overcoming the challenges associated with their fabrication. The demonstrated performance enhancement in CO₂ separation highlights the potential of these membranes for large-scale industrial applications.

Teaching Interests

Leaders bear the responsibility of nurturing the next generation who possess a combination of skills, personality, and a commitment to personal growth. Among the various pedagogical terms, I find "scaffolding" to be particularly fitting. Scaffolding can be likened to a supportive framework that enhances a student's capacity for self-directed learning by tailoring the leader's guidance based on the student's abilities and progress toward their goals. I strive for a process-oriented scaffolding approach that allows students to confront challenges directly during the pursuit of their objectives, thereby fostering the development of diverse problem-solving skills. Through this approach, leaders can provide a supportive framework that takes into account the individual abilities of their students and establish a systematic plan for goal attainment. Simultaneously, students can gain confidence by engaging in a step-by-step problem-solving process, ultimately fostering a sense of pride in their expertise across various situations.

With the mindset of a leader committed to process-oriented scaffolding, I aim to guide students who tend to embrace ignorance to confront new knowledge. It is challenging to build a deep sense of trust when individuals pretend to possess knowledge in areas where they are actually lacking. Just as a single drop of black ink instantly darkens the water in a bottle, I have observed how inaccurate knowledge can have a detrimental impact on both individuals and the organizations they belong to throughout various research projects.

Hence, I emphasize the importance of avoiding unwarranted pride in what one does not know. True knowledge signifies an opportunity to fill the gaps within an individual's reservoir of understanding. By facing facts and recognizing personal growth, one can truly evolve into an expert in their field. I am eager to undertake the task of objectively evaluating the level of learning and nurturing students who consistently reflect on their shortcomings and fearlessly engage with new knowledge.