Hierarchically porous Mg-MOF-74 monolith with high MOF loading for carbon dioxide capture and separation

The growing interest in advanced CO2 capture technology has led researchers to explore various materials, with metal–organic frameworks (MOFs) emerging as a promising option due to their large surface areas and designable functionalities. Despite their potential, the powder form of MOFs brings many difficulties in practical applications. To overcome these challenges, the design of MOF monoliths has attracted great attention in recent years. In this work, metal oxide nanoparticles are used to stabilize Pickering emulsions and in-situ transformed into MOFs to prepare hierarchically porous Mg-MOF-74 monoliths. The obtained materials exhibit large surface area of 659 m2/g and high MOF loading of ∼77 %. It is demonstrated that Mg-MOF-74 monolith gives excellent CO2 adsorption performance with a high CO2 saturation adsorption capacity of 4.31 ± 0.2 mmol/g at room temperature and atmospheric pressure. Moreover, the monolith exhibits a low CH4 saturation adsorption capacity of 0.73 ± 0.08 mmol/g, showing its potential for biogas separation. This work provides an adoptable approach to prepare MOF-based monolithic materials for applications in adsorption, separation, and other fields.