Shaping of Metal–Organic Frameworks: A Review

Abstract

Metal–organic frameworks (MOFs) have attracted a lot of attention in various applications such as molecular separation, catalysis, and gas delivery, due to their unique properties such as controllable structure, significantly specific surface area, and extensive porosity. However, conventional synthesis methods yield powdered MOFs, which cannot be directly used in the adsorption separation process due to such limitations as a high pressure drop, low mass transfer rate, and poor recyclability with scattering tendencies. Thus, it is crucial for practical applications to shape MOFs into various monoliths that allow an efficient processing, especially for industrial purposes. The existing forming methods are used to shape MOFs into films, pellets, tablets, gels, and honeycomb forms. At the same time, the shaping processes are generally accompanied by varying degrees of performance degradation of the original MOFs material, which is manifested in terms of loss of its adsorption capacity by a decrease in the specific surface area and porosity. Consequently, it is important to shape MOF monoliths into the appropriate shapes, mechanical strength, and stability, as well as to prevent the loss of the original properties in industrial applications. This paper reviews various strategies for shaping MOFs and discusses the impact of the shaping process on the properties of the MOFs as compared to their pristine powder form. It is believed this review will facilitate the industrial application of MOFs in gas processing applications.