Using Polysulfone Hollow-Fiber Member to Separate H2 from Petrochemical Process Tail Gas

[[abstract]]The rate of gas diffusion is inversely proportional to the gas molecule diameter; hydrogen gas molecular has smaller diameter and thus it has a greater diffusion coefficient than methane. Results of laboratory studies shown that when a gas mixture consisting of H2/CH4 = 30:70 is treated in a Hollow-fiber member under 5 kg/cm2, the hydrogen concentration is raised from 30 mol% to 71 mol%. If the Hollow-fiber member is re-arranged in series connection without controlling the operating pressure (free permeation), the recovered hydrogen concentration can be as high as 88 mol%. Additionally, using H2/CH4 = 50:50 as the influent gas mixture and controlling the influent pressure at 5 kg/cm2, the resulting hydrogen concentration can be raised from 50 mol% to 92 mol%, if the Hollow-fiber member is re-arranged in series connection without controlling the permeating pressure (free permeation), the recovered hydrogen concentration can reach 94 mol%. Therefore, Hollow-fiber member can be implemented to recover hydrogen gas from the hydrogen-rich petrochemical process tail gas at low pressure; the recovered hydrogen can be further utilized with higher add-on value. This hydrogen-recovery method has the advantage of low capital cost, simple to operate and small energy consumption