Zeolitic Imidazolate Frameworks (ZIF): A Potential Membrane for CO2/CH4 Separation

Removal of carbon dioxide (CO2) from natural gas is of importance because the existence of CO2 in natural gas increases the cost of the sweetening process. In recent years, membrane technology has emerged as an attractive alternative in separating CO2 from CH4 due to its economical, efficient, and environmentally-friendly process. Here, we review the different types of membranes used in CO2/CH4 gas separation. Zeolitic imidazolate frameworks (ZIFs) membranes are emphasized and ZIF-8 membranes are selected for further discussion due to their remarkable properties, including high chemical and thermal stability, facile and controllable pore apertures, and high CO2 permeance. Different types of methods used for the synthesis of ZIF membranes and the challenges encountered in the growth of the membrane are summarized. Potential use of microwave technology in fabricating a continuous and low-defects ZIF membrane within a short period of time are discussed and highlighted. In conclusion, future direction and perspectives are indicated.