Hydrolysis of MgH2 in MgCl2 solutions as an effective way for hydrogen generation

V. Berezovets 1,
A. Kytsya 1,
Yu. Verbovytskyy 1,
I. Zavaliy 2,
V. Yartys 3

1 Фізико-механічний інститут ім. Г.В. Карпенка НАНУ, Львів, Україна
2 Фізико-технологічний інститут металів та сплавів НАН України, Київ
3 Institute for Energy Technology, Kjeller NO-2027 , Норвегія



Magnesium hydride (MgH2) has a high hydrogen storage capacity (7.6 wt%) and the Mg element is abundant on the earth. Due to its strong reduction ability, even at room temperature it can provide the hydrogen yield reaching 15.2 wt% H (1703 mL/g) when interacting with water, which makes it very attractive for the application in supplying hydrogen for autonomous H energy systems. However, the hydrolysis reaction is rapidly inhibited by the Mg(OH)2 passivation layer formed on the surface of MgH2. In order to remove the passivation film and improve the efficiency of the MgH2 hydrolysis process, several methods including alloying, ball milling, changing the aqueous solution, have been successfully utilized. In this paper the process of hydrolysis of magnesium hydride in aqueous solutions of MgCl2 used as a promotor of the interaction has been studied in detail. It was found that the initial hydrolysis rate, pH of the reaction mixture, and overall reaction yield are all linearly dependent of the logarithm of MgCl2 concentration. It has been shown that pH of the reaction mixture in the presence of MgCl2 is well described by considering a system “weak base and its salt with strong acid” type buffer solution. Reference data for this hydrolysis reaction were also carefully analyzed. The mechanism and the kinetic model of the process of MgH2 hydrolysis in water solutions involved passivation of the MgH2 surface by the formed Mg(OH)2 precipitate followed by its repassivation have been proposed. The obtained after the hydrolysis reactions precipitates were studied using XRD and EDS. It was found also that the final products of reaction consist of Mg(OH)2 (brucsite type) and remaining MgH2. This fact shows that the formation of solid species such as MgCl2 xMgO yH2O at the studied conditions is unlikely and decreasing of pH the reaction mixture has a different nature.

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[1] Lukashev R. V., Yakovleva N. A., Klyamkin S. N., Tarasov B. P. Effect of mechanical activation on the reaction of magnesium hydride with water, Russian J. Inorg. Chem, 2008, vol. 53, No. 3, pp. 343–349.

[2] Grosjean M.-H., Zidoune M. and Roué L. Hydrogen production from highly corroding Mg-based materials elaborated by ball milling, J. Alloys Compd., 2005, vol.404, pp. 712–715.

[3] Grosjean M.-H., Zidoune M., Roué L. and Huot J.-Y. Hydrogen production via hydrolysis reaction from ball-milled Mg-based materials, Int. J. Hydrogen Energy, 2006, vol. 31, pp. 109–119.

[4] Tayeh T., Awad A.S., Nakhl M., Zakhour M., Silvain J.-F. and Bobet J.-L. Production of hydrogen from magnesium hydrides hydrolysis, Int. J. Hydrogen Energy,2014, vol. 39, pp. 3109–3117.

[5] Kojima Y., Suzuki K.-I., Kawai Y. Hydrogen generation by hydrolysis reaction of magnesium hydride, J. Mat. Sci., 2004, vol. 39, pp. 2227–2229.

[6] Adeniran J. A., Akinlabi E. T., Chen H.-S., Fono-Tamo R., Jen T.-C. Organic acid-catalyzed hydrolysis of magnesium hydride for generation of hydrogen in a batch system hydrogen reactor, Proc. of the World

Congress on Eng. and Computer Sci., 2017, vol II, WCECS 2017, October 25–27, 2017, San Francisco, USA.

[7] Hiraki T., Hiroi S., Akashi T., Okinaka N., Akiyama T. Chemical equilibrium analysis for hydrolysis of magnesium hydride to generate hydrogen, Int. J. Hydrogen Energy, 2012, vol. 37, pp. 12114–12119.

[8] Chao C.H., Jen T.C. Reaction of magnesium hydride with water to produce hydrogen, Applied Mech. Mat., 2013, vol. 302, pp. 151–157.

[9] Makhaev V. D., Petrova L. A., Tarasov B. P. Hydrolysis of magnesium hydride in the presence of ammonium salts, Russian J. Inorg. Chem., 2008, vol. 53, No. 6, pp. 858–860.

[10] Kushch S. D., Kuyunko N. S., Nazarov R. S., Tarasov B. P. Hydrogen-generating compositions based on magnesium. Int. J. Hydrogen Energy, 2011, vol. 36, pp. 1321–1325.

[11] Grosjean M.-H., Roué L. Hydrolysis of Mg–salt and MgH2–salt mixtures prepared by ball milling for hydrogen production, J. Alloys Compd.,2006, vol. 416, pp. 296–302.

[12] Tegel M., Schöne S., Kieback B., Röntzsch L. An efficient hydrolysis of MgH2-based materials, Int. J. Hydrogen Energy, 2017, vol. 42, pp. 2167–2176.

[13] Li S., Gan D., Zhu Y., Liu Y., Zhang G., Li L. Influence of chloride salts on hydrogen generation via hydrolysis of MgH2 prepared by hydriding combustion synthesis and mechanical milling, Trans. Nonferrous Met. Soc. China, 2017, vol. 27, pp. 562–568.

[14] Ouyang L., M. Ma, Huang M., Duan R., Wang H., Sun L., Zhu M. Enhanced hydrogen generation properties of MgH2-based hydrides by breaking the magnesium hydroxide passivation layer, Energies, 2015, vol. 8, pp. 4237–4252.

[15] Zhao Z., Zhu Y., Li L. Efficient catalysis by MgCl2 in hydrogen generation via hydrolysis of Mg-based hydride prepared by hydriding combustion synthesis, Chem. Commun.,2012, vol.48, pp.5509–5511.

[16] Tessier J.-P., Palau P., Huot J., Schulz R., Guaya D. Hydrogen production and crystal structure of ball-milled MgH2–Ca and MgH2–CaH2 mixtures, J. Alloys Compd., 2004, vol. 376, pp. 180–185.

[17] Xiao Y., Wu C., Wu H., Chen Y. Hydrogen generation by CaH2- induced hydrolysis of Mg17Al12 hydride, Int. J. Hydrogen Energy, 2011, vol. 36, pp. 15698–15703.

[18] Zhong H., Wang H., Liu J. W. et.al. Enhanced hydrolysis properties and energy efficiency of MgH2-base hydrides, J. Alloys Compd., 2016, vol. 680, pp. 419–426.

[19] Ma M., Ouyang L., Liu J., Wang H. et.al. Air-stable hydrogen generation materials and enhanced hydrolysis performance of MgH2–LiNH2 composites, J. Power Sources, 2017, vol. 359, pp. 427–434.

[20] Uesugi H., Sugiyama T., Nakatsugawa I., Ito T. Production of hydrogen storage material MgH2 and its application, J. Japan Inst. Light Met., 2010, vol. 60, pp. 615–618.

[21] Huang M., Ouyang L., Wang H., Liu J., Zhu M. Hydrogen generation by hydrolysis of MgH2 and enhanced kinetics performance of ammonium chloride introducing, Int. J. Hydrogen Energy,2015, vol. 40, pp. 6145–6150.

[22] Gan D., Liu Y., Zhang J., Zhang Y., Cao C., Zhu Y., Li L. Kinetic performance of hydrogen generation enhanced by AlCl3 via hydrolysis of MgH2 prepared by hydriding combustion synthesis, Int. J. Hydrogen Energy, 2018, vol. 43, pp. 10232–10239.

[23] Hoops S., Sahle S., Gauges R. et.al, COPASI—a complex pathway simulator, Bioinformatics, 2006, vol. 22, pp. 3067–3074.