Hydrogen extraction characteristics of high-temperature proton conductor ceramics for hydrogen isotopes purification and recovery

To develop high-efficiency and economical hydrogen isotope purification and recovery processes for a tritium extraction system in a fusion reactor, hydrogen extraction characteristics of an electrochemical hydrogen pump using high-temperature proton conductors were studied. The driving forces of hydrogen transportation in the proton conductors are electric potential difference, which can extract hydrogen isotopes selectively from a solid breeder blanket purge gas with low-pressure hydrogen isotope gas. In the experiments, a one-end closed tube made of proton-conducting ceramic CaZr0.9In0.1O3-alpha, (effective electrode area: 160 cm(2)) was developed because of its high chemical stability, mechanical strength, and durability in a series of perovskite-type proton conductors. The hydrogen pumping characteristics were evaluated over the temperature range from 923 K to 1073 K by extraction of 664-1200 ppm H-2 balanced with He, H-2 was selectively extracted from and the mixture of He and H-2 at the rate of Faraday's Law under an applied voltage of 3.5 V DC. In the case of He with 0.12% H-2 at 1023K and at 1.15V DC, the maximum hydrogen evolution rate was 0.12 ml/min, the hydrogen recovery efficiency was more than 99%, suggesting the extraction of hydrogen could be operated with a current efficiency close to unity. The possible application of hydrogen pumps for the TES of CIPITISE at CIAE has been estimated. (C) 2014 Elsevier B.V. All rights reserved.