An apparatus for the separation and optional recovery of a first gas from a gas mixture containing said first gas and other gases, different from said first gas, by a cyclic adsorption/desorption process using a loose particulate sorbent for gas adsorption; wherein said sorbent is provided in a stack of at least two adjacent, parallel, spaced-apart layers in a rigid vacuum chamber of said apparatus; wherein said layers being provided in two or more, laterally-extending, axially spaced-apart, parallel stacks ; wherein each layer comprises a flexible fabric enclosing said sorbent; wherein said fabric is permeable to said gas mixture but impermeable to said sorbent; wherein said fabric of each layer is attached to, and enclosed by, a stiff frame of said layer; wherein said vacuum chamber of said apparatus has an inlet and outlet for gases on axially opposite sides of said vacuum chamber of said apparatus; and wherein each of said layers extends axially within said vacuum chamber of said apparatus and wherein said vacuum chamber of said apparatus is characterized by said layers forming a serpentine flow path for gas through said vacuum chamber of said apparatus; wherein the vacuum chamber of said apparatus also has - pairs of axially-extending baffles and that are adjacent to, and on laterally opposite sides of said inlet and outlet , respectively of said vacuum chamber of said apparatus and that extend vertically from a bottom wall to a top wall of said vacuum chamber of said apparatus and - pair of laterally- and vertically-extending baffles and between each stack on opposite lateral sides of the vacuum chamber of said apparatus and that extend vertically from a bottom wall to a top wall of said vacuum chamber of said apparatus to form the serpentine flow path. wherein each layer comprises a flexible fabric enclosing said sorbent; wherein said fabric is permeable to said gas mixture but impermeable to said sorbent; wherein said fabric of each layer is attached to, and enclosed by, a stiff frame of said layer; wherein said vacuum chamber of said apparatus has an inlet and outlet for gases on axially opposite sides of said vacuum chamber of said apparatus; and wherein each of said layers extends axially within said vacuum chamber of said apparatus and wherein said vacuum chamber of said apparatus is characterized by said layers forming a serpentine flow path for gas through said vacuum chamber of said apparatus; wherein the vacuum chamber of said apparatus also has - pairs of axially-extending baffles and that are adjacent to, and on laterally opposite sides of said inlet and outlet , respectively of said vacuum chamber of said apparatus and that extend vertically from a bottom wall to a top wall of said vacuum chamber of said apparatus and - pair of laterally- and vertically-extending baffles and between each stack on opposite lateral sides of the vacuum chamber of said apparatus and that extend vertically from a bottom wall to a top wall of said vacuum chamber of said apparatus to form the serpentine flow path. - pairs of axially-extending baffles and that are adjacent to, and on laterally opposite sides of said inlet and outlet , respectively of said vacuum chamber of said apparatus and that extend vertically from a bottom wall to a top wall of said vacuum chamber of said apparatus and - pair of laterally- and vertically-extending baffles and between each stack on opposite lateral sides of the vacuum chamber of said apparatus and that extend vertically from a bottom wall to a top wall of said vacuum chamber of said apparatus to form the serpentine flow path. <EOS>