Flux-reducing tendency of pd-based membranes employed in butane dehydrogenation processes

Abstract

We report on the effect of butane and butylene on hydrogen permeation through thin state-of-the-art Pd–Ag alloy membranes. A wide range of operating conditions, such as temperature (200–450◦C) and H2 /butylene (or butane) ratio (0.5–3), on the flux-reducing tendency were investigated. In addition, the behavior of membrane performance during prolonged exposure to butylene was evaluated. In the presence of butane, the flux-reducing tendency was found to be limited up to the maximum temperature investigated, 450◦C. Compared to butane, the flux-reducing tendency in the presence of butylene was severe. At 400◦C and 20% butylene, the flux decreases by ~85% after 3 h of exposure but depends on temperature and the H2 /butylene ratio. In terms of operating temperature, an optimal performance was found at 250–300◦C with respect to obtaining the highest absolute hydrogen flux in the presence of butylene. At lower temperatures, the competitive adsorption of butylene over hydrogen accounts for a large initial flux penalty.