“Mortar-and-cobblestone” type carbon pellets with interlinked C3H6-philic domains and mesoporous transport channels for propylene/propane separation

Adsorptive separation of propylene/propane is an energy efficient way to produce high purity propylene, which is an essential chemical for the production of a variety of important monomers/polymers. The central task is to devise porous materials that can recognize the subtle difference between propylene/propane. The understanding of the selective adsorption and dynamic diffusion behaviors in nanopores at different length scales is key for efficient separation, however, remains elusive. Here we target at this issue by devising “mortar-and-cobblestone” type carbon pellets (MCCs) as model adsorbents, which showed tunable combinations between micropores and mesopores. As the volume ratio of mesopore to micropore increases from 0.37 to 1.33, the adsorption capacity of propylene increases from 2.4 to 2.9 mmol g−1 at 100 kPa and 298 K, and its diffusion rate is 3.28 times increased. In particular, the adsorption of propane displays a unique two-step diffusion behavior in the MCCs, which quantifies the contribution of the mass transport mesopores and gas sieving micropores to their adsorptive separation. In addition, the MCCs are in pellet form and mechanically strong with a compressive strength of 17.4 MPa, which further ensures their potential in molecular separation practice.