In situ pressure and temperature monitoring during the conversion of Mg into MgH2 by high-pressure reactive ball milling

Catalytic effects of various forms of nickel on the synthesis rate and hydrogen desorption properties of nanocrystalline magnesium hydride (MgH2) synthesized by controlled reactive mechanical milling (CRMM)

“…Another very recent paper by Doppiu et al [10] reports the results of reactive mechanical milling of a mixture of Mg + 1 at.% Ni (coarse) under high hydrogen pressures of 10, 40 and 90 bar. It is observed that during early stages of milling the rate of conversion of Mg into MgH 2 is much faster during milling under 40 and 90 bar of hydrogen as compared to 10 bar although after 18 h the total yield of MgH 2 obtained under 90 bar pressure is ∼95% and that under 10 bar ∼80%, i.e., only slightly smaller.…”

“…11). The desorption kinetics and apparent activation enthalpy for desorption were not evaluated [10].…”

“…Those publications can be divided into two groups. In the first group, a relatively coarse Ni powder with the particle size in the micrometer range was either used as a catalyst for the synthesis of Mg into MgH 2 by reactive milling as well as conventional (non-reactive) milling followed by hydrogenation [5][6][7][8][9][10], or mixed with commercial MgH 2 [11][12][13][14][15] to improve its sorption/desorption properties after mechanical milling. It must be clarified that in the first group of publications some authors examined the effect of a number of transition metals as catalysts, with Ni being only one of a few.…”

Influence of the dopant during the one step mechano-chemical synthesis of sodium alanate

“…In this paper, the one-step mechano-chemical synthesis using reactive ball milling of NaAlH 4 doped with different additives is described. Monitoring the pressure and temperature during milling enabled insights into the reactions occurring during synthesis [9,10], which had been so far a purely empirical process. It is demonstrated how this information can be used to effectively screen different dopants for NaAlH 4 .…”

“…To ensure a high energy input during the milling, the vial was filled with 37 stainless steel balls and a ball-to-powder ratio of 50:1. The vial used is specially designed for in-situ monitoring of the temperature and pressure during milling (evico-magnetics, operating range 1-150bar) [9]. Powder handling was done in argon atmosphere inside a glove box with low oxygen and water content (<1 ppm).…”