无机化学学报
無機化學學報
무궤화학학보
JOURNAL OF INORGANIC CHEMISTRY
2012年
7期
1489-1494
,共6页
裴立超%韩树民%朱惜林%刘宝忠%赵鑫%扈琳
裴立超%韓樹民%硃惜林%劉寶忠%趙鑫%扈琳
배립초%한수민%주석림%류보충%조흠%호림
储氢合金%相转变%镧氧化合物%吸氢动力学
儲氫閤金%相轉變%鑭氧化閤物%吸氫動力學
저경합금%상전변%란양화합물%흡경동역학
hydrogen storage alloy%phase transition%La hydride compound%hydriding kinetic
采用感应熔炼技术在Ar气氛保护下制备得到LaMg2Ni与Mg2Ni合金.X射线衍射(XRD)图表明LaMg2Ni合金在吸氢过程中分解为LaH3相和Mg2NiH4相,放氢过程中LaH3相转化为La3H7相.与Mg2Ni合金相比,LaMg2Ni合金显示出优良的吸氢动力学性能,这是由于镧氢化合物的存在及其在吸氢过程中所发生的相转变所造成的.LaMg2Ni合金280 s内吸氢即可达到最大储氢量的90％以上,而Mg2Ni合金则需要1200 s才能达到,且在相同温度下LaMg2Ni合金的吸氢反应速率常数大于Mg2Ni合金速率常数.镧氧化合物不仅有利于改善动力学性能,而且可以提高热力学性能.LaMg2Ni合金中的Mg2Ni相氢化反应焓与熵分别为-53.02kJ·mol-1和84.96 J·K-1·mol-1(H2),这一数值小于单相Mg2Ni氢化反应焓与熵(-64.50 kJ·mol-1,- 123.10 J·Kq· mol-1(H2)).压力-组成-温度(P-C-T)测试结果表明在603 K至523 K温度范围内,LaMg2Ni合金储氢容量保持稳定为1.95wt％左右,然而Mg2Ni合金的储氢容量则由4.09wt％衰减为3.13wt％,Mg2Ni合金的储氢容量在523K低温下仅为603 K时的76.5％,表明镧氢化合物能够改善Mg2Ni合金低温下的吸放氢性能.
採用感應鎔煉技術在Ar氣氛保護下製備得到LaMg2Ni與Mg2Ni閤金.X射線衍射(XRD)圖錶明LaMg2Ni閤金在吸氫過程中分解為LaH3相和Mg2NiH4相,放氫過程中LaH3相轉化為La3H7相.與Mg2Ni閤金相比,LaMg2Ni閤金顯示齣優良的吸氫動力學性能,這是由于鑭氫化閤物的存在及其在吸氫過程中所髮生的相轉變所造成的.LaMg2Ni閤金280 s內吸氫即可達到最大儲氫量的90％以上,而Mg2Ni閤金則需要1200 s纔能達到,且在相同溫度下LaMg2Ni閤金的吸氫反應速率常數大于Mg2Ni閤金速率常數.鑭氧化閤物不僅有利于改善動力學性能,而且可以提高熱力學性能.LaMg2Ni閤金中的Mg2Ni相氫化反應焓與熵分彆為-53.02kJ·mol-1和84.96 J·K-1·mol-1(H2),這一數值小于單相Mg2Ni氫化反應焓與熵(-64.50 kJ·mol-1,- 123.10 J·Kq· mol-1(H2)).壓力-組成-溫度(P-C-T)測試結果錶明在603 K至523 K溫度範圍內,LaMg2Ni閤金儲氫容量保持穩定為1.95wt％左右,然而Mg2Ni閤金的儲氫容量則由4.09wt％衰減為3.13wt％,Mg2Ni閤金的儲氫容量在523K低溫下僅為603 K時的76.5％,錶明鑭氫化閤物能夠改善Mg2Ni閤金低溫下的吸放氫性能.
채용감응용련기술재Ar기분보호하제비득도LaMg2Ni여Mg2Ni합금.X사선연사(XRD)도표명LaMg2Ni합금재흡경과정중분해위LaH3상화Mg2NiH4상,방경과정중LaH3상전화위La3H7상.여Mg2Ni합금상비,LaMg2Ni합금현시출우량적흡경동역학성능,저시유우란경화합물적존재급기재흡경과정중소발생적상전변소조성적.LaMg2Ni합금280 s내흡경즉가체도최대저경량적90％이상,이Mg2Ni합금칙수요1200 s재능체도,차재상동온도하LaMg2Ni합금적흡경반응속솔상수대우Mg2Ni합금속솔상수.란양화합물불부유리우개선동역학성능,이차가이제고열역학성능.LaMg2Ni합금중적Mg2Ni상경화반응함여적분별위-53.02kJ·mol-1화84.96 J·K-1·mol-1(H2),저일수치소우단상Mg2Ni경화반응함여적(-64.50 kJ·mol-1,- 123.10 J·Kq· mol-1(H2)).압력-조성-온도(P-C-T)측시결과표명재603 K지523 K온도범위내,LaMg2Ni합금저경용량보지은정위1.95wt％좌우,연이Mg2Ni합금적저경용량칙유4.09wt％쇠감위3.13wt％,Mg2Ni합금적저경용량재523K저온하부위603 K시적76.5％,표명란경화합물능구개선Mg2Ni합금저온하적흡방경성능.
LaMg2Ni and Mg2Ni alloys were prepared by inductive melting under Ar atmosphere.X-ray diffraction (XRD) shows that during hydrogenation,LaMg2Ni alloy decomposes to LaH3 phase and Mg2NiH4 phase,in dehydriding process this alloy releases H2 and LaH3 phase changes to La3H7 phase.Compared with Mg2Ni alloy,on account of the existence of La hydride compound and phase transition from La3H7 phase to LaH3 phase in hydriding process,LaMg2Ni alloy shows better hydriding kinetics.It is within 280 s for LaMg2Ni alloy to reach 90％ of the maximum hydrogen absorption capacity,while it needs 1 200 s for pristine Mg2Ni alloy to do so.The rate constant of LaMg2Ni alloy is larger than that of Mg2Ni alloy at the same temperature.La hydride compound is beneficial not only to the enhancement of hydriding kinetics but also to the improvement of the thermodynamic properties.The enthalpy and entropy for the hydriding Mg2Ni in the LaMg2Ni alloy are -53.02 kJ· mol-1,84.96 J·K-1·mol-1 (H2),respectively.Mg2NiH4 in LaMg2Ni alloy is less stable than pristine Mg2Ni alloy (-64.50 kJ·mol-1and -123.10 J·K-1·mol-1 (H2)).Pressure-Composition- Temperature (P-C-T) measurement results show that the hydrogen storage capacity of LaMg2Ni alloy is about 1.95wt％ and is kept stable from 603 K to 523 K,while the hydrogen storage capacity of pristine Mg2Ni alloy declines distinctly form 4.09wt％ to 3.13wt％ with the reduction of temperature from 603 K to 523 K.The hydrogen storage capacity of pristine Mg2Ni alloy at lower temperature (523 K) is only 76.5％ when compared to that at 603 K,suggesting that La hydride compound could improve the hydriding/dehydriding properties of Mg2Ni alloy at low temperature.
