Implementation of a Core–Shell Design Approach for Constructing MOFs for CO₂ Capture

Abstract

Adsorption-based capture of CO2 from flue gas and from air requires materials that have a high affinity for CO2 and can resist water molecules that competitively bind to adsorption sites. Here, we present a core–shell metal–organic framework (MOF) design strategy where the core MOF is designed to selectively adsorb CO2, and the shell MOF is designed to block H2O diffusion into the core. To implement and test this strategy, we used the zirconium (Zr)-based UiO MOF platform because of its relative structural rigidity and chemical stability. Previously reported computational screening results were used to select optimal core and shell MOF compositions from a basis set of possible building blocks, and the target core–shell MOFs were prepared. Their compositions and structures were characterized using scanning electron microscopy, transmission electron microscopy, and powder X-ray diffraction. Multigas (CO2, N2, and H2O) sorption data were collected both for the core–shell MOFs and for the core and shell MOFs individually. These data were compared to determine whether the core–shell MOF architecture improved the CO2 capture performance under humid conditions. The combination of experimental and computational results demonstrated that adding a shell layer with high CO2/H2O diffusion selectivity can significantly reduce the effect of water on CO2 uptake.

Positional functionalizations of metal–organic frameworks through invasive ligand exchange and additory MOF‐on‐MOF strategies: A review

“…recently pioneered an efficient CO 2 capture system under humid conditions by utilizing a Zr‐based MOF‐on‐MOF approach (Figure 18). [81] This study commenced with a systematic computational exploration to identify the core and shell MOF components that are crucial for enhanced performance. To achieve a high CO 2 capturing ability, the incorporation of Lewis basic amine groups is deemed essential.…”

“… Efficient CO 2 capture from the bifunctional MOF‐on‐MOF system. Adapted from Reference 81 with permission (parts of figures). Copyright 2023.…”

CO2 Capture and Conversion into Carbon-Based Tribofilm by In Situ Tribochemical Reaction for Green Lubrication

“…However, the release of adsorbed CO 2 is endothermic and requires a significant amount of energy. Additionally, porous materials, including zeolites, − metal organic frameworks (MOFs), − and porous polymers, , are also used to capture CO 2 through physical adsorption. Although the weak physical adsorption of CO 2 by porous materials can improve the energy efficiency of the capture process, their adsorption capacity is limited compared with chemical adsorption.…”

Scalable and Highly Porous Membrane Adsorbents for Direct Air Capture of CO2

“…Amine groups can be incorporated into solid sorbents by impregnation in porous supports. ,, A variety of inorganic porous supports have been explored to incorporate amines including fume silica, silica monoliths, ordered mesoporous silica such as MCM-41 with regular cylindrical mesopores and SBA-15 with both mesopores and intrawall pores, mesoporous γ alumina, and metal–organic frameworks (MOFs). − CO 2 sorption capacity as high as 1–3 mmol/g was reported for simulated air. The sorption is often subject to slow kinetics due to CO 2 diffusion, and the pore structure and chemistry exert significant influence on CO 2 sorption capacity and kinetics. , The strong interactions between amines and CO 2 may also retard CO 2 diffusion at low temperatures. , For example, CO 2 sorption in a polyethylenimine (PEI)-modified silica is higher at 75 °C than at 25 °C because of the faster diffusion at the higher temperature. , These inorganic supports are relatively expensive to produce on a large scale.…”