Hydrolysis of light metals and hydrides can potentially be used for the generation of hydrogen on-board fuel cell vehicles, or, alternatively, for refilling their fuel tanks with H₂ generated and pressurised without compressor on site, at near-ambient conditions. Implementation of this approach requires solution of several problems, including the possibility of controlling H₂ release and avoiding thermal runaway. We have solved this problem by developing the apparatus for the controlled generation of pressurised H₂ using hydrolysis of Mg or MgH₂ in organic acid solutions. The development is based on the results of experimental studies of MgH₂ hydrolysis in dilute aqueous solutions of acetic, citric, and oxalic acids. It was shown that the hydrogen yield approaches 100% with a fast hydrolysis rate when the molar ratio acid/MgH₂ exceeds 0.9, 2.0, and 2.7 for the citric, oxalic, and acetic acids, respectively. In doing so, the pH of the reaction solutions after hydrolysis corresponds to 4.53, 2.11, and 4.28, accordingly, testifying to the buffer nature of the solutions “citric acid/magnesium citrate” and “acetic acid/magnesium acetate”. We also overview testing results of the developed apparatus where the process rate is effectively controlled by the control of the acid concentration in the hydrolysis reactor.

The work presents the results of studies concerning preparation of graphene-like nanomaterials by graphite oxide reduction, preparation of nickel-graphene catalysts, magnesium-graphene, and...

Metal hydride (MH) hydrogen storage and compression systems with near-atmospheric H₂ suction pressure are necessary for the utilization of the low-pressure H₂ produced by solid oxide electrolyzers or released as a byproduct of chemical industries. Such systems should provide reasonably high productivity in the modes of both charge (H₂ absorption at P_L ≤ 1 atm) and discharge (H₂ desorption at P_H = 2–5 atm), which implies the provision of H₂ equilibrium pressures Peq < P_L at the available cooling temperature (T_L = 15–20 °C) and, at the same time, Peq > P_H when heated to T_H = 90–150 °C. This work presents results of the development of such systems based on AB₅-type intermetallics characterized by Peq of 0.1–0.3 atm and 3–8 atm for H₂ absorption at T_L = 15 °C and H₂ desorption at T_H = 100 °C, respectively. The MH powders mixed with 1 wt.% of Ni-doped graphene-like material or expanded natural graphite for the improvement of H₂ charge dynamics were loaded in a cylindrical container equipped with internal and external heat exchangers. The developed units with a capacity of about 1 Nm³ H₂ were shown to exhibit H₂ flow rates above 10 NL/min during H₂ charge at ≤1 atm when cooled to ≤20 °C with cold water and H₂ release at a pressure above 2 and 5 atm when heated to 90 and 120 °C with hot water and steam, respectively.

Nanocomposites of polylactide with graphite nanoplateletes (GNPs) and reduced graphene oxide (RGO) are prepared by liquid-phase synthesis. A comparative study of the mechanical, electric, and thermophysical characteristics of the compositions depending on the nature of the nanofillers is carried out. An insignificant difference in the mechanical parameters of the compositions containing GNPs and RGO is established. At the same time, when studying the electrical properties, it is found that the use of RGO as a filler produces of composites with a lower percolation threshold than in the case of GNPs and increased conductivity. The differential scanning calorimetry (DSC) method shows that compositions containing GNPs have higher degree of crystallinity in comparison with similar compositions containing RGO. This is caused by the structure of the filled compositions, which influences the nucleation rate of polylactide (PLA) crystallites on the surface of ordered planar nanoparticles of GNP and imperfect RGO particles. Thus, the use of different carbon nanofillers may promote the production of compositions that differ in their characteristics.