Professor Shinichiro Noro and his group have clarified that hydrocarbon gas can be separated even if water molecules coexist. To refine hydrocarbon gas with an intramolecular double bond, such as propylene, it is necessary to separate the gas from other kinds of hydrocarbon gas. It is currently refined by a costly distillation method. Professor Noro et al. conducted experiments with water in a porous material capable of selectively separating propylene, and demonstrated for the first time in the world that propylene separation performance was almost maintained even in the presence of water.