Membrane techniques have achieved an acknowledged technological level for different gas separation applications. These include the air separation for inert gas production or oxygen enrichment, the separation of water vapor from pressurized air, and the separation hydrogen/carbon monoxide and hydrogen/nitrogen during the synthesis of ammonia. Other examples are for instance the carbon dioxide/methane separation during ternary oil extraction and the separation of organic vapors from vent or process gases in the chemical industry and during the handling of gasoline. it is thus obvious that membrane techniques have a great potential for off-gas cleaning. By combining membrane separation with adsorption very low emissions can be achieved economically and safely.