報告書番号

Q04011

タイトル（和文）

硫黄サイクルハイブリッド水素製造法用アノード電極材料の探索(その2) -―耐硫酸性と導電性を両立するペロブスカイト型酸化物の検討―-

タイトル（英文）

Survey of Anode Materials used for Sulfur-based Hybrid Hydrogen Production (Part 2)‐ Study of Perovskite with High Corrosion Resistance and Electrical Conductivity ‐

概要 （図表や脚注は「報告書全文」に掲載しております）

水素エネルギー社会の到来が予想される昨今、低コストかつプロセスが簡易な硫黄サイクルハイブリッド法が非化石燃料による水素製造法として注目されている。前報にて導電性の発現ならびにその向上手法を検討したパイロクロア型酸化物よりも高い導電率が期待できるペロブスカイト型チタン酸化物の導電性と耐硫酸性を調べ、電解槽のアノード極としての適用可能性を評価した。(1) Aサイトに希土類元素(RE)を部分置換したSr1-zREzTiO3+d、およびAサイトを不定比化した上、NbやTaをBサイトに部分置換したSr1-xTi1-yMyO3+d(M：Nb, Ta)の導電率は、チタン系パイロクロアより高く、1～10S/cmを示した。(2) Sr1-xTi1-yMyO3+dは耐硫酸性にも優れ、導電率と共に当初の目標値に近づいたことから、セラミックス組成の不定比化や異種金属の一部置換等の新技法を採用することにより、アノード極の作製指針を得た。

概要 （英文）

According to the establishment of hydrogen energy cycle in the near future, sulfur-based hybrid cycle for hydrogen production is attracted the attention as a low cost and a simple hydrogen producing process through the electrolysis of 2H2O+SO2 H2 + H2SO4 at approximately 353K and through the thermal decomposition of H2SO4 H2O +SO2 +1/2O2 at approximately 1123K. In the previous paper, it was clarified that the development of high quality anode which has high corrosion resistance, high electrical conductivity, and low electrolysis potential was useful for high efficient hydrogen producing, and that RE2-xTi2O7-d (RE=Yb, Y, Gd, Sm, Nd, Pr, La) pyrochlores were available for anode material of the electrolysis cell. In addition, some new techniques were proposed, such as A-site non-stoichiometry and B-site substituents techniques. In this paper, an application of electronic conductive ceramics, such as A-site doped Sr1-xRExTiO3+d (RE=Nd, Pr, La) and B-site doped and non-stoichiometric Sr1-xTi1-yREyTiO3+d (RE=Nb, Ta) perovskites, to the substitute anode for platinum group material were investigated for the point of electrical conductivity and corrosion resistance under the simulated electrolysis condition. (1) From the crystallographic study, it was revealed that Ti3+ were stable in the A-site doped Sr1-xRExTiO3+d (RE=Nd, Pr, La) and B-site doped and non-stoichiometric Sr1-xTi1-yREyTiO3+d (RE=Nb, Ta) at 353K after the hydrogen reduction treatment of the perovskites.(2) From the electrical conductivity measurements, it was revealed that the conductivities of A-site doped Sr1-xRExTiO3+d (RE=Nd, Pr, La) and B-site doped and non-stoichiometric Sr1-xTi1-yREyTiO3+d (RE=Nb, Ta) perovskites were ranged from 1 to 10 S/cm at 353K which were higher than those of RE2-xTi2O7-d (RE=Yb, Y, Gd, Sm, Nd, Pr, La) pyrochlores. (3) From the corrosion test, it was revealed that the corrosion resistance of Sr1-xTi1-yREyTiO3+d (RE=Nb, Ta) perovskites were maintained under the electrolysis condition. From the above results, it was concluded that the electronic conductive perovskites might be available for anode material of the electrolysis cell.

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