Water vapor permeation and its influence on gases through a zeolite-4A membrane

It is known that water adsorption in zeolites can severely affect the adsorption and, thus, the permeation of other gases. This work proposes an investigation about the contributions of both surface and gas translation diffusion on permeation of some light gases (H-2, CH4 and CO) in the presence of water for the 4A zeolite within a wide range of temperature (300-700 K). As main results, the contributions of the two considered diffusional mechanisms and their relative weights are determined, showing in a quantitative way that the presence of water vapor significantly reduces the adsorption of the other species. The extent to what this effect influences the overall permeation process is reported considering the variation of temperature, allowing a good prediction of the permeance decrease of H-2, CH4 and CO when mixed with water vapor. The water adsorption drives the permeation of the water itself, and, in the meantime, hinders the adsorption and, hence, the permeation of the other gases.