Reversible hydrogen storage at low temperatures of high sulfur petroleum coke‑magnesium composites prepared by nano melt infiltration

Abstract

Petroleum porous activated carbon (PPC), prepared from high‑sulfur petroleum coke, possesses a rich pore structure and can serve as an inexpensive matrix material for the preparation of nano‑magnesium hydrogen storage materials, which shows broad potential for application. Based on this, the pore structure distribution and evolution characteristics of PPC under different activation conditions were studied, and a series of magnesium (Mg)-based hydrogen storage materials were prepared and characterized as promising candidates for hydrogen storage. Samples prepared by the balling-pelleting-impregnation method exhibited desired hydrogen release at 30 °C, and the peak hydrogen desorption temperatures were divided into 80 °C and 300 °C, with 0.6 wt% reversible hydrogenation/dehydrogenation at 100 °C under the influence of nanosizing, physical isolation by PPC pores, and the synergistic catalysis of the MgC bond. The key factors affecting Mg loading, including melting temperature, processing time, and ball milling usage, were systematically investigated. Confirmatory experiments and simulation results indicated that evaporation is the predominant factor affecting the stable deposition of Mg nano-clusters in PPC, due to its significantly lower boiling point compared to bulk Mg during infiltration. This finding prompted the formulation of a balling-pellet-impregnation-condensing multi-driver synergistic strategy, resulting in a magnesium loading of 48 %, which warrants further investigation.