2015 Volume 40 Issue 1 Pages 28-34
Hydrogen is attracting attention as a clean fuel that produces no CO2 emission at the stage of use. In Japan, fuel cell vehicle, which is a car running by converting hydrogen to electrical energy, is commercially available now. Hydrogen can be produced using existing equipment, but hydrogen recovery decreases, because specifications of impurities in hydrogen for fuel cell vehicles are so severe. As a result, production efficiency of high-purity hydrogen is reduced. If high-purity hydrogen is produced from fossil fuel at low production efficiency, CO2 emissions increase. To solve these problems, we developed a new hydrogen purification system with a hybrid-type membrane that features CO2 membranes and H2 membranes arranged in alternating stages. In this system, H2 or CO2 was respectively permeated through each type of membranes, and the partial pressure of H2 or CO2 was alternatively increased. Therefore, this system can increase the recovery rate of high-purity hydrogen up to over 90%, as well as simultaneously recovering by-product CO2. Recently, the system was scaled up to pilot plant. In this plant we are conducting long life tests at 2MPa(20 bar) by using gases produced from steam reforming of propane.
