2. State of the art

Gas permeation technology based on dense polymers has been developing rapidly since the 1980s, with a number of companies specializing in industrial gas technologies using glassy polymer materials. The initial focus was on air separation and hydrogen purification (Air Products, Air Liquide-Medal, Parker-Hannifin, Ube) and natural gas treatment (Natco-Cynara, UOP). Regulations on air pollutant emissions from the 1990s onwards also stimulated the development of elastomer materials for the recovery of Volatile Organic Compounds (VOCs) from the air by MTR in the USA, then Sihi-GKSS and Borsig in Europe. In comparison, inorganic materials (zeolites, carbon molecular sieves, graphenes, MOFs, etc.) are still rarely used, despite the remarkable separation performance they can offer. However, recent spectacular advances in both nanostructured material synthesis and processing technologies point...