The present invention relates to a device and a process for separation by simulated moving bed comprising a plurality of adsorbers (1, 2) which are positioned in series and arranged alternately for upflow and downflow, each adsorber (1, 2) being divided into n adsorption chambers each comprising one adsorbent bed, the n adsorbent beds being separated by n plates for injecting at least one feed and a desorbent and withdrawing at least one extract and a raffinate.