Molecular gate functionalized dendrimer membrane for CO_2 capture

摘要

Novel hydroxyl poly(amidoamine)(PAMAM) dendrimer was developed as CO_2 molecular gate membrane material based on our new concept for obtaining excellent CO_2 selectivity comparable to that of amine solution. The dendrimer showed higher CO_2 permeability than H_2, even though H_2 is much smaller than CO_2. Its CO_2/H_2 selectivity and CO_2 permeability coefficient were 730 and 8.7 × 10~(-12) m~3(STP) m m~(-2)s(-1)Pa~(-1), respectively, for a feed of 5 vol % of CO_2 and 95 vol % of H_2 at 80 %RH and 25 °C. To form a composite membrane of dendrimers, an in-situ modification method was applied to commercial ultrafiltration hollow fiber membrane. The method successfully modified the surface of hollow fiber substrate in a module with conventional PAMAM dendrimer to show a high CO_2/N2 selectivity of 400. Cost of CO_2 separation from a product of water-gas shift reaction was estimated. The cost estimates indicate that a molecular gate membrane having large CO_2/H_2 selectivity expected from performance of our dendrimer will separate CO_2 from the shift reaction product at a cost of 900 JPY/t-CO_2, when a membrane unit cost is 30,000 JPY/m~2.