Hydrogen Extraction Using One-end Closed Tube Made of CaZrO₃-based Proton-conducting Ceramic for Tritium Recovery System

Abstract

Abstract In a nuclear fusion reactor, tritium and its compounds must be recovered for the purpose of fuel recycling and hydrogen gas must be separated from a gas mixture with hydrogen compounds and other molecules. Proton-conducting ceramics have the proper characteristics to aid in this separation. The present paper describes the performance of a hydrogen pump using the one-end closed tube made of a proton-conducting ceramic (CaZr0.9In0.1O3-α, Effective electrode area: 47 cm2) at 800°C. Hydrogen gas was selectively extracted from Ar-H2 mixed gas at the rate of Faraday's low under an applied voltage of 3.5 V. This test apparatus could also electrolyze water vapor and/or decompose methane at the anode to generate hydrogen at the cathode. In the case of argon gas with 0.1% hydrogen, 0.1% methane and 1.2% water vapor, the hydrogen evolution rate was 0.34m1/min at 3.5 V. The current density was 1.2 mA/cm2 and the current efficiency was 79%. Experimental data suggest that water vapor has an important role for the hydrogen extraction from the mixture with methane. KEYWORDS: proton-conducting ceramicCaZr0.9In0.1 O3-α hydrogen pumpelectrolysis of water vapordecomposition of methanetritium recovery system