AMMONIA SELECTIVE HOLLOW FIBERS

Microporous polypropylene hollow fibers can be coated with a 1.9 mu m layer of perfluorosulfonic acid polymer ('Nafion'), to give membranes selective for ammonia. The permeability, of the order of 10(4) barrers , is comparable with that obtained previously for thick flat perfluoro sulfonic acid membranes, though the permeance is much higher. The sele ctivity for ammonia over hydrogen can be as high as 500:1 at room temp erature; it is much higher for ammonia over nitrogen. This selectivity drops as the temperature rises. These composite membranes will be com mercially valuable if they can be made to withstand the high pressures characteristic of ammonia synthesis.