Abstract: A continuous method of producing a process fluid gas from a feed stream that includes the process fluid and impurities. The method includes: (a) providing a first and second vessel, each vessel containing one or more regenerable purifier materials for removing at least one of the impurities from the feed stream; (b) removing at least one of the impurities by passing the feed stream through one or the other of the vessels to provide a purified process fluid gas, with the vessel being maintained at a first temperature during the removal of impurities; and (c) regenerating the purifier materials in the vessels at a second temperature and during the time when it is not purifying the feed stream by flowing a portion of the purified process fluid or the feed stream or a separate source of the process fluid gas therethrough.