Influences of Ni-Co-B catalyst on the thermal decomposition of light-weight NaNH2-NaBH4 hydrogen storage material

Abstract

NaNH 2 and NaBH 4 were utilized to prepare a composite hydrogen storage material, NaNH 2 -NaBH 4 . To improve the thermal decomposition kinetics of NaNH 2 -NaBH 4 , which is crucial for hydrogen-release performance, Ni-Co-B was selected as a catalyst. To prepare the catalyst-promoted light-weight hydrogen storage materials, a composite hydrogen storage system was synthesized via a ball milling method with NaNH 2 , NaBH 4 , and Ni-Co-B. X-ray diffraction patterns show that the crystal structure of the NaNH 2 -NaBH 4 is well maintained after adding catalysts. In addition, Na 3 BN 2 and metal Na were detected as by-products in the Ni-Co-B-promoted NaNH 2 -NaBH 4 (with a molar ratio of 2:1) after the thermal decomposition process. In addition, thermogravimetry-differential thermal analysis indicates that the main decomposition stages of the metal boride-promoted NaNH 2 -NaBH 4 materials were split into three stages. Furthermore, the catalytic effects on the thermal decomposition kinetics were evaluated. The activation energy of the Ni-Co-B-promoted NaNH 2 -NaBH 4 below 250 C is 99 kJ/mol, which is only 62.0% of that of pristine NaNH 2 -NaBH 4 (2/1), implying better kinetics in the low temperature decomposition range. V C 2014 AIP Publishing LLC. [http://dx.

Review on Ammonia Absorption Materials: Metal Hydrides, Halides, and Borohydrides

“…Research efforts have been focused on developing and verifying onboard automotive hydrogen storage materials to meet these targets. Many kinds of complex materials have been synthesized and studied for storing a high capacity of hydrogen, such as amide/imide systems like LiNH 2 /Li 2 NH, − complex metal hydrides like LiAlH 4 − and NaAlH 4 , − and borohydrides like LiBH 4 , − NaBH 4 , − and Mg­(BH 4 ) 2 . − However, these materials require improvements of the properties for development as practical materials. For instance, the amide/imide systems form byproduct gas during dehydrogenation, complex metal hydrides are not easily reversible, and borohydrides have sluggish kinetics.…”

Role of Metal Electronegativity in the Dehydrogenation Thermodynamics and Kinetics of Composite Metal Borohydride–LiNH2 Hydrogen Storage Materials

“…It is known that the dehydrogenation kinetics of composite hydrogen storage materials can be improved by adding catalysts, such as Mg–Co–B, Ni–Co–B, and so on. , On the basis of the knowledge that unstable metal borohydride is liable to dehydrogenation, it is also interesting whether the electronegativity of metal M in M­(BH 4 ) n –LiNH 2 (M = Li, Mg, Ca) can effectively affect the dehydrogenation performances, without the participation of catalysts. Herein, various borohydrides were mixed with LiNH 2 by liquid ball milling, and the dehydrogenation performances of Ca­(BH 4 ) 2 –LiNH 2 , Mg­(BH 4 ) 2 –LiNH 2 , and LiBH 4 –LiNH 2 are compared by means of thermogravimetry–differential thermal analysis–mass spectroscopy (TG–DTA–MS), X-ray diffraction (XRD) test, and activation energy calculation.…”

“…27 It is known that the dehydrogenation kinetics of composite hydrogen storage materials can be improved by adding catalysts, such as Mg−Co−B, 28 Ni−Co−B, and so on. 29,30 On the basis of the knowledge that unstable metal borohydride is liable to dehydrogenation, it is also interesting whether the…”

Insight to the Thermal Decomposition and Hydrogen Desorption Behaviors of NaNH2–NaBH4 Hydrogen Storage Composite

“…The corresponding NaNH 2 –NaBH 4 system promises to be more appropriate for the development of new hydrogen storage materials, with the price one tenth of that of LiBH 4 . , Furthermore, the electronegativity of metal Li and Na are almost the same, 1.0 and 0.9, respectively. We did a lot of investigations on the dehydrogenation performance of NaNH 2 –NaBH 4 (2/1 molar ratio), such as the desorption property of pristine and Co–B-, Ni–Co–B-, , and Mg–Co–B-doped NaNH 2 –NaBH 4 (2/1 molar ratio) hydrogen storage materials . The activation energy for the Co–B-doped NaNH 2 –NaBH 4 (2/1 molar ratio) is only 70 kJ/mol, 43.9% of that of the pristine NaNH 2 –NaBH 4 (2/1 molar ratio).…”

“…41,42 Furthermore, the electronegativity of metal Li and Na are almost the same, 1.0 and 0.9, respectively. We did a lot of investigations on the dehydrogenation performance of NaNH 2 −NaBH 4 (2/1 molar ratio), such as the desorption property of pristine 43 and Co− B-, 44 Ni−Co−B-, 45,46 and Mg−Co−B-doped NaNH 2 −NaBH 4 (2/1 molar ratio) hydrogen storage materials. 47 is only 70 kJ/mol, 43.9% of that of the pristine NaNH 2 −NaBH 4 (2/1 molar ratio).…”