A device is disclosed for conducting an adsorption/desorption swing reaction. The desorption step of the reaction is conducted at least in part at a temperature below 100° C. Dry steam is used for purging the reactor and the adsorbent bed in the reactor. For this purpose the device has a water reservoir, and a vacuum source in fluid connection with the water reservoir and the reactor. During the desorption step the vacuum source causes water to evaporate, and the water vapor to flow through the reactor.