A (V)PSA unit for purifying a gas stream by adsorption is provided. The (V)PSA unit comprises, arranged successively in the direction of flow of the feed gas stream, a rotary-structured adsorbent wheel configured so as to drive the gas stream therethrough in an axial manner and allowing the feed gas to dry to a level corresponding to a dew point below 30 C., and an adsorber with a centripetal radial configuration, comprising a bed of particulate adsorbent.

A structured adsorbent assembly is described, which is usefully employed for pressure swing adsorption (PSA) processing of ambient air to generate high purity oxygen. The structured adsorbent assembly in various implementations may include cellulosic carbon molecular sieve fibers formed by spinning of precursor cellulose followed by pyrolysis of the spun fibers, as an argon-selective adsorbent, or AgX zeolite contained on and/or in polymeric fibers, as an argon-selective adsorbent, and such argon-selective adsorbents may be in combination with nitrogen-selective adsorbent such as LiX zeolite contained on and/or in polymeric fibers. The structured adsorbent assembly may be employed in PSA systems and processes to achieve highly efficient and economic generation of high purity oxygen for applications such as distributed gasification power generation.

Described are processes and equipment that are useful to produce purified oxygen gas using a cryogenic adsorption bed to remove impurities such as nitrogen-containing impurities (e.g., nitrogen (N.sub.2), nitrogen oxides, ammonia, amines), water, carbon dioxide, carbon monoxide, hydrocarbons, among others, from oxygen gas.