Feed gas contaminant removal in ion transport membrane systems

An ion transport membrane system comprising (a) a pressure vessel (513) having an interior, an exterior, an inlet, and an outlet; (b) a plurality of planar ion transport membrane modules (501,503,505,507,509) disposed in the interior of the pressure vessel (513) and arranged in series, each membrane module (501,503,505,507,509) comprising mixed metal oxide ceramic material and having an interior region and an exterior region, wherein any inlet and any outlet of the pressure vessel are in flow communication with exterior regions of the membrane modules (501,503,505,507,509); (c) one or more gas manifolds (519) in flow communciation with interior regions of the membrane modules (501,503,505,507,509) and with the exterior of the pressure vessel (513); and (d) a guard bed (1805,1807) in flow communication with at least one of the one or more gas manifolds (519).