成果報告書詳細
管理番号20150000000197
タイトル*平成26年度中間年報 水素利用等先導研究開発事業 エネルギーキャリアシステム調査・研究 溶融塩を用いた水と窒素からのアンモニア電解合成
公開日2015/12/19
報告書年度2014 - 2014
委託先名アイ’エムセップ株式会社 一般財団法人電力中央研究所
プロジェクト番号P14021
部署名新エネルギー部
和文要約
英文要約Title:Advancement of Hydrogen Technologies and Utilization Project
Analysis and Development on Hydrogen as an Energy Carrier
Electrolytic Ammonia Synthesis from Water and Nitrogen in Molten Salts
(FY2014-FY2015) FY2014 Annual Report

In order to integrate and effectively utilize renewable energy produced in its
abundant region in the world, it is most desirable to use ammonia as an energy
carrier. This project demonstrates the applicability of an ammonia synthesis
method using the electrochemical reaction of water and nitrogen in molten salts for
the above mentioned purpose and establishes it as an ammonia mass production
technology that outperforms the Haber-Bosch process. This innovative ammonia
synthesis method, which is I’ MSEP’s original technology, is based on the following
total reaction:

3 H2O + N2 → 2 NH3 + 3/2 O2

In this project, the bench-scale equipment (100A scale) of electrolytic ammonia
synthesis is constructed to evaluate its performance and characteristics. We are
currently conducting research and development to improve each component reaction
of electrolytic ammonia synthesis (cathodic nitrogen reduction, ammonia formation
in molten salt, anodic oxygen evolution and hydrogen permeation in metal
membrane).
The cathodic nitrogen reduction (1/2N2 + 3e-→ N3-) was promoted by
exerting a porous electrode structure that facilitated the N2 supply into and N3-
removal from the electrode. The immersion behavior of the molten salt into a porous
electrode was also investigated by an in situ observation with an air-tight heating
chamber and a long focus microscope.
We also investigated the ammonia formation reaction between water vapor
and N3- in molten salt in relation to the N3- concentration, the rate of the water vapor
supply, and so on. The yield against the theoretical amount of ammonia estimated
from the initially added amount of N3-, which completely reacts with water vapor,
exceeds 80 % in a condition that resembled a bench-scale equipment operation. It
can be further improved by exerting the structure of the reaction field. An in situ
measurement of infrared spectroscopy was also conducted with a diffuse reflectance
apparatus to investigate the dissolved species in the melt during the ammonia
formation reaction.
Nickel ferrite is a promising material for oxygen production anode. To reduce
internal resistance of the electrode, nickel ferrite thin film on a metal substrate was
investigated. The film-type electrode prepared by a plasma spraying process showed
excellent initial characteristics of near 100 % of current efficiency for anodic oxygen
evolution.
Hydrogen permeation metal membrane is necessary to decrease the applied
voltage for electrolytic ammonia synthesis. We investigated a method of fixing the
metal membrane in which molten salt did not leak out through the fixation part. The
composition of the metal alloy with a bcc structure showed the possibility of a
hydrogen permeation rate 40 times larger than palladium at 623K that was
estimated through pulsed NMR and PCT measurements.
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