Abstract

Single and mixed gas permeation experiments for 1,3-butadiene and n- butane were carried out for several polyimide and other glassy polymer membranes at pressures up to 1.5 atm and 323 K. They displayed large permeation coefficients to 1,3-butadiene, P C 4H 6 , of 4–200 Barrer and very large ideal separation factors (permeability ratios of 1,3-butadiene over n- butane for single gas permeation), α id , of 30–200 at 1 atm. The large P C 4H 6 was attributed to large diffusion and solubility coefficients to 1,3-butadiene. The diffusion coefficient to 1,3-butadiene for each polymer was a little larger than or similar to that to propylene, whereas the diffusion coefficient to n- butane was much smaller than that to propane, indicating the relatively small effective diameter for diffusion of 1,3-butadiene probably because of its rigid and straight molecular shape. For mixed gas permeation, the separation factors, α, were reduced by a factor of 1 3 – 1 6 as compared with α id due to the strong plasticization effect of 1,3-butadiene. However, the polyimides had still high performance.

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