Amino-functionalized SAPO-34 membranes for CO_2/CH_4 and CO_2/N_2 separation

摘要

SAPO-34 seeds and membranes were functionalized with several organic amino cations, such as ethylenediamine, hexylamine, and octylamine. The successful incorporation of the amino groups in the SAPO-34 framework was confirmed by Fourier transform infrared (FTIR) and X-ray photoemission (XPS) spectroscopies. The resultant SAPO-34 membranes were evaluated for the separation of CO _2/CH_4 and CO_2/N_2 gas mixtures. CO_2/CH_4 selectivities as high as 245, with CO_2 permeances of ～5 × 10~(-7) mol m~(-2) s~(-1) Pa~(-1) at 295K and 138 kPa, were observed for an optimum ethylenediamine-functionalized membrane, which corresponded to a ～40% increase in the separation index, as compared to the nonfunctionalized SAPO-34 membrane. Similarly, the CO_2/N_2 separation performance was highly improved with the incorporation of ethylenediamine. CO _2/N_2 selectivities as high as 39, with CO_2 permeances of ～2.1 × 10~(-7) mol m~(-2) s~(-1) Pa~(-1) at 295K and 138 kPa, were observed for an optimum ethylenediamine-functionalized membrane, which corresponded to a ～167% increase in the separation index, as compared to the nonfunctionalized SAPO-34 membrane.