An apparatus for selectively adsorbing gas during adsorption processes and desorbing gas during desorption processes. A tube has a porous sidewall, and at each end is an end-fitting sealingly connected thereto. A particulate porous gas storage material is located within the tube, wherein the porosity prevents the material, but allows gases, to pass therethrough. A selected gas from a porous inner tube, a heating coil, or a heat exchanger located within the tube may provide heat for the desorption processes, and the selected gas or heat exchanger may provide cooling during the adsorption processes.