Development of CO2 Separation Membrane Modules Containing Ionic Liquid and those Applications toward Hydrogen Production

概要

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Hydrogen is attracting attention as a clean fuel that produces no carbon dioxide emissions at the stage of use. Hydrogen could be produced from fossil fuels using existing equipment in refineries, but in such production schemes, the hydrogen recovery rate decreases when purity is increased to 99.99% or higher as is required for fuel cells. To solve this problem, we developed a new hydrogen purification system with a hybrid-type membrane that features CO2 membranes and H2 membranes arranged alternately, and which utilizes the high temperature and high pressure in the hydrogen production unit. This system achieves increased recovery of high-purity hydrogen compared to existing technologies. Such a system requires a highly stable and CO2-selective membrane. As ionic liquids (ILs) are known for their negligible volatility, we modified the chemical structure of some ILs to increase their CO2 selectivity. We thus set out to develop a CO2 separation membrane incorporating our novel ILs. The membranes we developed show remarkably high CO2/H2 selectivity from mixed gases of CO2 and hydrogen.