Medical oxygen concentrators: a review of progress in air separation technology

Air separation by adsorption to produce oxygen for industrial and medical applications represents one of several important commercialized adsorption processes. Fueled by the introduction of synthetic zeolites, adsorbent and process development for air separation have progressed steadily over the last five decades. Early progress was driven primarily by large-scale industrial applications, however, small-scale medical oxygen concentrators (MOC) soon followed. This review presents an overview of the various types of commercially available MOCs, as well as the underlying adsorption technology. Key developments and essential concepts are summarized for air separation technology as it applies to both large and small-scale systems. Specific research targeting oxygen concentrators is also reviewed. The introduction of pulse flow oxygen conserving methodology has given rise to portable concentrators. Pulse flow represents not only a disruptive technology for the small-scale medical products, but also introduces operational challenges not present in large-scale industrial air separation. Process intensification utilizing small adsorbent particles and fast cycles is reviewed along with other key developments in air separation that apply to both large and small-scale systems. Challenges to further improvements in the medical concentrators are explored and opportunities for future research are identified.