Conversion of CH₄ and Hydrogen Storage via Reactions with MgH₂-12Ni

The main key to the future transition to a hydrogen economy society is the development of hydrogen production and storage methods. Hydrogen energy is the energy produced via the reaction of hydrogen with oxygen, producing only water as a by-product. Hydrogen energy is considered one of the potential substitutes to overcome the growing global energy demand and global warming. A new study on CH₄ conversion into hydrogen and hydrogen storage was performed using a magnesium-based alloy. MgH₂-12Ni (with the composition of 88 wt% MgH₂ + 12 wt% Ni) was prepared in a planetary ball mill by milling in a hydrogen atmosphere (reaction-involved milling). X-ray diffraction (XRD) analysis was performed on samples after reaction-involved milling and after reactions with CH₄. The variation of adsorbed or desorbed gas over time was measured using a Sieverts'-type high-pressure apparatus. The microstructure of the powders was observed using a scanning transmission microscope (STEM) with energy-dispersive X-ray spectroscopy (EDS). The synthesized samples were also characterized using Fourier transform infrared (FT-IR) spectroscopy. The XRD pattern of MgH₂-12Ni after the reaction with CH₄ (12 bar pressure) at 773 K and decomposition under 1.0 bar at 773 K exhibited MgH₂ and Mg₂NiH₄ phases. This shows that CH₄ conversion took place, the hydrogen produced after CH₄ conversion was then adsorbed onto the particles, and hydrides were formed during cooling to room temperature. Ni and Mg₂Ni formed during heating to 773 K are believed to cause catalytic effects in CH₄ conversion. The remaining CH₄ after conversion is pumped out at room temperature.