Adsorptive separation is very important in industry. Generally, the process uses porous solid materials such as zeolites, activated carbons, or silica gels as adsorbents. With an ever increasing need for a more efficient, energy-saving, and environmentally benign procedure for gas separation, adsorbents with tailored structures and tunable surface properties must be found. Metal-organic frameworks (MOFs), constructed by metal-containing nodes connected by organic bridges, are such a new type of porous materials. They are promising candidates as adsorbents for gas separations due to their large surface areas, adjustable pore sizes and controllable properties, as well as acceptable thermal stability. This critical review starts with a brief introduction to gas separation and purification based on selective adsorption, followed by a review of gas selective adsorption in rigid and flexible MOFs. Based on possible mechanisms, selective adsorptions observed in MOFs are classified, and primary relationships between adsorption properties and framework features are analyzed. As a specific example of tailor-made MOFs, mesh-adjustable molecular sieves are emphasized and the underlying working mechanism elucidated. In addition to the experimental aspect, theoretical investigations from adsorption equilibrium to diffusion dynamics via molecular simulations are also briefly reviewed. Furthermore, gas separations in MOFs, including the molecular sieving effect, kinetic separation, the quantum sieving effect for H2/D2 separation, and MOF-based membranes are also summarized (227 references).

in MOFs 873 1.3. Scope and Structure of This Review 874 2. MOFs for Gas-Phase Adsorptive Separations 874 2.1. Selective Adsorptions and Separations of Gases 874 2.1.1. Carbon Dioxide (CO 2 ) 874 2.1.2. Oxygen (O 2 ) 879 2.1.3. Hydrogen (H 2 ) 881 2.1.4. Gaseous Olefin and Paraffin 882 2.1.5. Harmful and Unsafe Gases 884 2.1.6. Nobel Gases and Others 886 2.2. Selective Adsorptions and Separations of Chemicals in the Vapor Phase 887 2.

Among the large family of metal-organic frameworks (MOFs), Zr-based MOFs, which exhibit rich structure types, outstanding stability, intriguing properties and functions, are foreseen as one of the most promising MOF materials for practical applications. Although this specific type of MOF is still in its early stage of development, significant progress has been made in recent years. Herein, advances in Zr-MOFs since 2008 are summarized and reviewed from three aspects: design and synthesis, structure, and applications. Four synthesis strategies implemented in building and/or modifying Zr-MOFs as well as their scale-up preparation under green and industrially feasible conditions are illustrated first. Zr-MOFs with various structural types are then classified and discussed in terms of different Zr-based secondary building units and organic ligands. Finally, applications of Zr-MOFs in catalysis, molecule adsorption and separation, drug delivery, and fluorescence sensing, and as porous carriers are highlighted. Such a review based on a specific type of MOF is expected to provide guidance for the in-depth investigation of MOFs towards practical applications.

Biomimetic MOF: Extremely stable MOFs with different open metal sites and ultra‐large 1D channels, PCN‐222 (Fe, Mn, Co, Ni, Cu, and Zn), have been assembled with eight‐connected Zr6 clusters and redox‐active metalloporphyrin motifs. PCN‐222(Fe) shows peroxidase‐like activity in aqueous solution, exhibiting highly effective biomimetic oxidation on a number of substrates.