Proposition of CO2 removable technology using membrane for Hydrogen Station

摘要

As the energy consumption in the world has been increasing since the Industrial Revolution, CO2 emission has been increasing and causes a global warming. However, an increase in the CO2 emission with the increase of the energy consumption can be decreased drastically only by dulling economic growth. Especially, big control of the CO2 emission cannot expect because the developing country of BRICs etc. consumes huge energy along with economic growth, and is emitting enormous CO2. Therefore, the energy of Japan had shifted from the thermal power with the fossil fuel to the nuclear power generation without CO2 emission. The world, however, has accelerated the shift from the nuclear power generation to the new energy by which the first nuclear plant in Fukushima be destroyed by the East Japan great earthquake in 2011.3.11. The world can only depend on the energy supply with the fossil fuel so that the new energy has problems such as a low electric power generation, reliability, and the cost, etc. Therefore, an immediate spread of the fuel cell with high energy conversion efficiency is expected from the world. Although Fuel Cell can use oxygen from air easily, almost hydrogen is produced from fossil fuel by the steam reforming reaction. Therefore, this reformed gas is sure to contain CO and CO2, though CO that is the poisoning material of the electrode catalyst is removed by the shift converter, CO2 is supplied to PEFC with hydrogen. However, it is necessary to remove CO2 before it is supplied to PEFC because CO2 in the anode gas decreases the diffusion polarization of hydrogen. Generally, though the method of the CO2 removal has a chemical absorption method, a physical absorption technique, a low temperature processing, an oxygen combustion separation and the PSA separation, etc., these methods cause the decrease in system efficiency by additional energy, making to high cost by expensive catalyst use and the enlargement of the system. Therefore, we propose the selective CO2 facilitated transport membranes that doesn't need an additional energy and can achieve the miniaturization and lowering the cost. Moreover, because CO2 is separated only by passing the reformed gas through the tube where this film was applied, this membrane can be applied to a hydrogen station, a fuel cell vehicle, a stationary power and energy production etc. Furthermore, this membrane can be also applied to a conventional thermal power plant and an engine system etc. This paper aims the development of the selective CO2 facilitated transport membranes using a carbonate as an alkaline catalyst. First, the CO2 permeable phenomenon is confirmed by using various aqueous carbonates. As a result, it has been understood that the CO2 permeability can be confirmed by most aqueous carbonates, and the cesium carbonate with strong deliquescence penetrates a lot of CO2 especially. Because the CO2 permeable speed depends on the distance between CO2 absorption side and CO2 emission side, we develop the membrane with carbonate as the alkaline catalyst. As a result, we accomplished the thin film process of the CO2 permeable membrane using a modified polyamide.