Eutectic Phenomenon of LiNH2-KH Composite in MH-NH3 Hydrogen Storage System

Hydrogenation of a lithium-potassium (double-cation) amide (LiK(NH2)2), which is generated as a product by ammonolysis of litium hydride and potassium hydride (LiH-KH) composite, is investigated in details. As a result, lithium amide (LiNH2) and KH are generated after hydrogenation at 160 °C as an intermediate. It is noteworthy that the mixture of LiH and KNH2 has a much lower melting point than that of the individual melting points of LiNH2 and KH, which is recognized as a eutectic phenomenon. The hydrogenation temperature of LiNH2 in the mixture is found to be significantly lower than that of LiNH2 itself. This improvement of reactivity must be due to kinetic modification, induced by the enhanced atomic mobility due to the eutectic interaction.

Purification of Lithium Carbonate from Sulphate Solutions through Hydrogenation Using the Dowex G26 Resin

Purification of lithium carbonate, in the battery industry, is an important step in the future. In this experiment, the waste lithium-ion batteries were crushed, sieved, leached with sulfuric acid, eluted with an extractant, and finally sulphate solutions were extracted, through selective precipitation. Next, sodium carbonate was first added to the sulphate solutions, to precipitate lithium carbonate (Li2CO3). After that, lithium carbonate was put into the water to create lithium carbonate slurry and CO2 was added to it. The aeration of CO2 and the hydrogenation temperature were controlled, in this experiment. Subsequently, Dowex G26 resin was used to remove impurities, such as the calcium and sodium in lithium carbonate. Moreover, the adsorption isotherms, described by means of the Langmuir and Freundlich isotherms, were used to investigate the ion-exchange behaviors of impurities. After removing the impurities, the different heating rate was controlled to obtain lithium carbonate. In a nutshell, this study showed the optimum condition of CO2 aeration, hydrogenation temperature, ion-exchange resin and the heating rate to get high yields and purity of lithium carbonate.

Effect of Hydrogenation Temperature on Distribution of Hydrogen Atoms in c-Si and a-Si: Molecular Dynamic Simulations

Crystalline silicon and amorphous silicon are main materials of solar cell. Under prolonged exposure to light, silicon will degrade in quality. Hydrogenation is believed can minimize this degradation by reduce the number of dangling bond. These Molecular dynamics simulations are aimed to elaborate the hydrogenation process of crystalline silicon and amorphous silicon and to elucidate effect of temperature on distribution of hydrogen atoms. Reactive Force Field is selected owing to its capability to describe forming and breaking of atomic bonds as well as charge transfer. Hydrogenation is performed at 300 K, 600 K, 900 K, and 1200 K. Hydrogenated silicon surface hinders further hydrogen atoms to be absorbed such that not all deposited Hydrogen atoms are absorbed by silicon surface. Generally, the higher hydrogenation temperature the more hydrogen atoms are absorbed. Increment of temperature from 900 K to 1200 K only enhances a few numbers of absorbed hydrogen atoms. However, it can enable hydrogen atoms to penetrate into deeper silicon substrate. It is also observed that hydrogen atoms can penetrate into amorphous silicon deeper than into crystalline silicon.

Hydrogen Absorpsivity-Desorbsivity of Mg Doped by Ni, Cu, Al Produced by Mechanical Alloying

Mg, in the form of MgH2,is one kinds of materials widely used as hydrogen storage materials. Absorption and desorption properties of hydrogen which comes from metal hydride depend on materials itself, addition of elements, as well as manufacturing method. In this research, Mg as hydrogen storage were prepared by mechanical alloying with Ni, Cu, and Al as element addition and variation milling time for 10, 20 and 30 hours. Some morphological analyses (XRD, SEM) were done to observe phase transformation. Absorption and desorption properties characterization were employed by DSC and hydrogenation tests. The improvement in milling time decreased particle size, therefore enhanced wt% of absorbed hydrogen and decrease onset desorption temperature. However, the excessive of agglomeration and cold welding on mechanical alloying process resulted in bigger particle size. Alloying elements, Al and Cu, served as catalyst, while Ni acted as alloying which reacted with hydrogen. Mg10wt%Al with 20 hours milling time at hydrogenation temperature 250°C, 3 atm pressure, and 1 hour holding time resulted in the highest weight percent of H2(0.38%wt). However, Mg10wt%Al with 30 hours milling time had the lowest onset temperature, 341.49°C

Component Characteristic of Lignite Semi-Coke Hydrogasification Residue

The residue of Inner Mongolia lignite semi-coke by different final temperature hydrogenation system methane of CO2 gasification reactivity is studied by means of thermo gravimetric and X-Ray Diffraction method. The results show that, with the rise of hydrogasification temperature, the residue aromaticity fa increase, the residual carbon microcrystalline tend to graphitization, CO2 reactivity decrease and residue CO2 reaction temperature raise. The final hydrogenation temperature residue CO2 gasification reaction conversion rate curves similar and curve to temperature increase in the direction of movement.