SELECTIVE PERMEATION OF AMMONIA AND CARBON-DIOXIDE BY NOVEL MEMBRANES

Experimental results are presented on membranes of novel composition which selectively permeate ammonia and carbon dioxide from mixtures containing hydrogen. The CO2-selective membrane, which consists of a thin liquid film of the salt hydrate tetramethylammonium fluoride tetrahydrate, exhibits a CO2 permeance of 4-1 x 10(-5) cm3/cm2.s.cmHg with selectivity, alpha(CO2/H2), ranging from 360-30. The NH3-selective membrane, poly(vinylammonium thiocyanate), displays a high NH3 permeance, 5-20 x 10(-5) cm3/cm2.s.cmHg, with alpha(NH3/N2) as high as 3600 and alpha(NH3/H2) as high as 6000. Such membranes, which retain H2 at pressure in the feed stream, may offer new opportunities in the design of separation processes.