Metal-organic frameworks for hydrocarbon separation: design, progress, and challenges

High-purity hydrocarbons are of great importance in various fields, including the electronics and chemical industries; however, the separation of hydrocarbons can be difficult because of their structural and chemical similarities. The established industrial practices of separating hydrocarbons usually involve energy-intensive procedures such as low-temperature distillation. Adsorptive separation using porous materials is deemed a promising alternative technology due to its potential to significantly reduce energy consumption. Porous materials, MOFs in particular, offer versatility in terms of their synthesis and structural design that can be facilely customized to meet the requirements of specific applications. By tailoring pore dimensions, surface functionality, and framework flexibility, MOF materials exhibit high selectivity for specific molecules in the separation and purification of hydrocarbons. With the rapid advances in reticular chemistry and crystal engineering, researchers have gained deep insight into the directional stitching of diverse building blocks, paving the way for the design of tailor-made MOF materials. This perspective summarizes three main strategies for developing MOFs for hydrocarbon separation: surface engineering, molecular docking, and size exclusion. In addition, the prospects of MOF materials for hydrocarbon separation are discussed, including future directions of addressing the challenges (barriers) for MOF sorbents to be competitive in practical applications, such as adsorption capacity and selectivity, stability, regenerability, scalability and cost-effectiveness, and industrial implementation. Energy-efficient hydrocarbon separation is of great significance. In this perspective, we discuss three main strategies in the design of MOF materials for hydrocarbon separation: surface engineering, molecular docking, and size exclusion.