Role of Carbon Order in Structural Transformations and Hydrogen Evolution Induced by Reactive Ball Milling in Cyclohexene

Demineralized Summit (DS) anthracite, DS annealed at 1673 K, and graphite are used to explore the effect of precursor order on structural transformations and H2 evolution that result during reactive ball milling. Carbon structure was assessed before and after milling with temperature-programmed oxidation, X-ray diffraction (XRD), ultraviolet Raman spectroscopy, N2 adsorption, He density, and solvent swelling. Graphite milled in cyclohexene is primarily nanocrystalline graphite, with 8 wt % amorphous content leading to low-temperature oxidation, swelling, increased surface area, and mesoporosity. Milling the disordered DS leads to signs of increased sp2 clustering, increased cross-linking, a significant ultramicroporosity with pores less than 8 Å, and low-temperature H2 evolution. The carbon fraction of annealed DS behaves similarly to graphite in the mill.