Role of Activated Carbon from Arabica Coffee Waste in Enhancing the Dehydrogenation Properties of Magnesium Hydride (MgH2) for Hydrogen Storage

Solid-state hydrogen storage requires improvement through catalyst-added methods to maximize performance. Magnesium Hydride (MgH2) is a type of solid-state hydrogen storage that is highly developed today but has many shortcomings, including high dehydrogenation temperatures. The use of carbon-based catalysts derived from biomass offers dual advantages by harnessing agricultural waste and supporting environmentally sustainable practices. This study utilized activated carbon (AC) from Arabica coffee agroindustry waste, specifically from pulp and parchment, as a catalyst to enhance the properties of MgH2. The activated carbons from coffee pulp and parchment (ACs) were produced through slow pyrolysis at 400 °C and chemically activated using potassium hydroxide (KOH) and sodium hydroxide (NaOH) solutions at various concentrations. Composites of MgH2 + 5 wt% AC were prepared through three hours of intensive mechanical alloying. Initially, the ACs were characterized using iodine adsorption, FTIR, TGA-DSC, and SEM analyses. The MgH2 + 5 wt% AC composites were then subjected to characterization through XRD, TGA-DTA, and SEM analysis. The results of the thermal investigations indicated that the AC catalysts from coffee pulp and parchment significantly reduced the onset temperature of dehydrogenation for MgH2. The lowest dehydrogenation temperature was 342.36 °C, achieved by adding 5 wt% AC produced from coffee parchment that was chemically activated using a 2% KOH solutions.