鋁對鑭鎳系儲氫合金活化與毒化過程之影響

The Influence of Al on the Activation and Poisoning Process of LmNi5-based Hydrogen Storage Alloys

林新智(H. C. Lin) ； 林昆明(K. M. Lin) ； 宋至偉(C. W. Sung) ； 吳昆秦(K. C. Wu) ； 林俊良(C. L. Lin)

《材料科學與工程》 38卷2期 (2006/06) Pp. 61-69

https://doi.org/10.6409/JMSE.200606.0061

摘要

應用儲氫合金來儲存與運輸氫氣是目前極力開發之儲氫新技術，在各種儲氫合金中，以鑭鎳系合金最爲優越，其具有活化容易、吸放氫速率快、儲氫量大及吸放氫平衡壓力遲滯小等優越性能。本研究以鑭鎳儲氫合金爲基礎，並添加適量鋁元素，探討合金之活化、吸放氫效能與毒化過程等。實驗結果顯示添加微量Al元素取代LmNi5儲氫合金中的Ni，其平台區氫壓大幅下降，甚至低於一大氣壓。LmNi4.8Al0.2儲氫合金在20℃活化潛伏期長達8小時，若將溫度提高至40℃，其活化潛伏期大幅縮減至45分鐘，並隨著溫度提高，活化所需時間逐漸減少。LmNi4.8Al0.2儲氫合金於CO毒性氫氣中吸放氫會產生毒化現象，CO分子濃度愈高，或是吸放氫循環次數愈多，合金被毒化的現象更加嚴重；提高吸放氫溫度，可有效降低儲氫合金之毒化現象。H2S毒性氫氣對於LmNi4.8Al0.2儲氫合金之毒化作用遠低於CO毒性氫氣。經過循環毒化之LmNi4.8Al0.2儲氫合金，於高純度氫氣中施予再活化處理，可有效恢復儲氫合金之吸放氫特性。

關鍵字

鑭鎳系儲氫合金 ； 活化 ； 吸放氫 ； 毒化

並列摘要

The method of using hydrogen storage alloys to store and carry hydrogen gas is a newly developing technique. Among several types of hydrogen storage alloys, LmNi5 alloys are most promising due to their easy activation, high absorption/desorption rate, large hydrogen storage capacity and a small hysteresis in equilibrium pressure of hydrogen absorption/desorption. In this study, the LmNi5 hydrogen storage alloys with slight addition of Al element are investigated on their characteristics of activation, hydrogen absorption/desorption and poisoning. Experimental results show that the slight addition of Al to substitute Ni element within LmNi5 alloys will reduce largely the plateau pressure, to be even lower than the atmospheric pressure. The incubation period of activation at 20℃ for LmNi4.8Al0.2 hydrogen storage alloy is about 8 hours. It decreases to be about 45 minutes if the activation temperature is 40℃. The higher the activation temperature, the shorter the incubation period of activation is. LmNi4.8Al0.2 hydrogen storage alloy will be poisoned during the hydrogen absorption if the hydrogen source has CO impurity. The higher the concentration of CO impurity and the more the cycles of hydrogen absorption/desorption, the severer of the poisoning. The poisoning phenomenon can be effectively inhibited by raising the hydrogen absorption/desorption temperature. The poisoning phenomenon is much slighter in the hydrogen source with H2S impurity than with CO impurity. The ability of hydrogen absorption/desorption of the as-poisoned LmNi4.8Al0.2 hydrogen storage alloy can be effectively recovered by the re-activation treatment in the hydrogen source with high purity.

並列關鍵字

LmNi5-based hydrogen storage alloys ； activation ； hydrogen absorption/desorption ； poisoning