利用XRD研究了ScMn2合金及其氢(氘)化物的晶体结构; 利用Sieverts装置测量了合金的吸氢活化性能、P-C-T曲线及吸氢动力学曲线; 利用热重--差热分析仪(TG-DSC)研究了ScMn2H3.6钝化后的放氢动力学. 结果表明, ScMn2的氢(氘)化物保持了母合金C14型Laves相结构, 吸氢造成的晶胞体积膨胀约为25%; ScMn2在室温常压下能与H(D)迅速发生反应, 具有优异的活化性能; 100 kPa, 298 K时, 1 mol ScMn2合金的贮氢量和贮氘量分别约为3.7和3.6 mol; ScMn2具有较低的吸、放氢滞后临界温度, 优异的平台特征以及较低的平台压, 适于H及其同位素贮存. 与室温平台压对应的合金氢化物的?H和?S分别为-45 kJ/mol和-80 J/(K?mol); ScMn2在113 kPa初始H2(D2)压强下吸氢(氘)动力学可用JMA模型描述, 反应级数为0.4, 吸氢和吸氘的表观活化能分别为(16±0.3)和(19±1.7) kJ/mol, 此活化能的差异使ScMn2有可能用于H同位素分离; 钝化后的合金氢化物在639 K时能完全放氢, 放氢的表观活化能为 (144±14) kJ/mol.
As an important rare--earth type Laves phase compound, ScMn2 alloy is endowed certain significance in the viewpoint of either theoretical or applicable investigation. In this study, the structures of ScMn2 alloy and its hydride (deuteride) are characterized by XRD. The hydrogen activation properties, pressure-concentration-temperature (P-C-T) curves and absorption kinetic curves of ScMn2 alloy are measured using Sieverts-type hydrogenator. The desorption kinetics of the passivated hydride are determined by TG-DSC. The results show that the hydride and deuteride of the alloy retain the C14 type Laves phase structure of the parent alloy, with the volume expansions of about 25%. ScMn2 possesses outstanding activation properties and can react quickly with hydrogen (deuterium) at room temperature and atmospheric pressure. The hydrogen and deuterium storage capacities of 1 mol ScMn2 are about 3.7 mol H and 3.6 mol D at 100 kPa and 298 K. ScMn2 has low hysteresis critical temperature for absorption and desorption, good plateau characteristics and relatively low plateau pressure, hence it is suitable for the storage of hydrogen isotopes. The enthalpy and entropy for formation of ScMn2 hydride at concentration corresponding to room temperature plateau pressure are -45 kJ/mol and -80 J/(K?mol), respectively. The hydriding kinetics of the alloy can be interpreted by Johnson-Mehl-Avrami (JMA) model, with the estimated reaction order of 0.4. The apparent activation energies for hydriding and deteuriding process are estimated to be (16±0.3) and (19±1.7) kJ/mol, respectively, the observed isotope effect on kinetics can possibly be applied to separation of hydrogen isotope. The passivated hydride can release completely at 639 K and the corresponding apparent activation energy is (144±14) kJ/mol.
[1] Pebler A, Gulbransen E A. Electrochem Technol, 1966; 4: 211
[2] Pourarian F, Fujii H, Wallace W E, Sinha V K, Kevin Smith H. J Phys Chem, 1981; 85: 3105
[3] Moriwaki Y, Gamo T, Iwaki T. J Less–Common Met, 1991; 172: 1028
[4] Li G, Nishimiya N, Satoh H, Kamegashira N. J Alloys Compd, 2005; 393: 231
[5] Guo X M, Wu E D. J Alloys Compd, 2008; 455: 191
[6] Li W H, Wu E D. J Alloys Compd, 2012; 511: 169
[7] Dwight A E. Trans Am Soc Met, 1961; 53: 479
[8] Park J M, Lee J Y. J Less–Common Met, 1991; 167: 245
[9] Kost M E, Raevskaya M V, Shilov A L, Yaropolova E I, Mikheeva V I. Russ J Inorg Chem, 1979; 24: 1803
[10] Griessen R, Driessen A, De Groot D G. J Less–Common Met, 1984; 103: 235
[11] Shilov A L, Kost M E, Kuznetsov N T. J Less–Common Met, 1985; 105: 221
[12] Hunter B A, Howard C J. LHPM: A Computer Program for Rietveld Analysis of X–ray and Neutron Powder Diffraction Patterns, ANSTO Report, 1998
[13] Srinivas G, Sankaranarayanan V, Ramaprabhu S. Int J Hydrogen Energy, 2007; 32: 2480
[14] Von Buch F, Lietzau J, Mordike B L, Pisch A, Schmid– Fetzer R. Mater Sci Eng, 1999; A263: 1
[15] Manchester F D, Khatamian D. Mater Sci Forum, 1988; 31: 261
[16] Liu B H, Kim D M, Lee K Y, Lee J Y. J Alloys Compd, 1996; 240: 214
[17] Wu E D, Li W H, Li J. Int J Hydrogen Energy, 2012; 37: 1509
[18] Hu Z L. Hydrogen Storage Materials. Beijing: Chemical Industry Press, 2002: 441
(胡子龙. 贮氢材料. 北京: 化学工业出版社, 2002: 441)
[19] Broom D P. Hydrogen Storage Materials. London: Springer–Verlag, 2011: 89
[20] Ohtani Y, Hashimoto S, Uchida H. J Less–Common Met, 1991; 172–174: 841
[21] Srinivas G, Sankaranarayanan V, Ramaprabhu S. J Alloys Compd, 2008; 448: 159
[22] Kissinger H E. Anal Chem, 1957; 29: 1702
[23] Hu R Z, Shi Q Z. Thermal Analysis Kinetics. Beijing: Science Press, 2001: 1
(胡荣祖, 史启祯. 热分析动力学. 北京: 科学出版社, 2001: 1)
[24] Fang Y Z, Liao M S, Hu L L. Thermochim Acta, 2006; 443: 179
[25] Hsieh Y C, Chou Y C, Lin C P, Hsieh T F, Shu C M. Aerosol Air Qual Res, 2010; 10: 212
