In situ formed graphene/ZnO nanostructured composites for low temperature hydrogen sulfide removal from natural gas

Abstract

Nanostructured composites of graphene and highly dispersed sub-20 nm sized ZnO nanoparticles (TRGZ) were prepared via a novel method combining freeze-drying and thermal annealing. A direct synthesis implies thermal reduction of graphite oxide and in situ ZnO formation which acted as mutual spacers preventing restacking of the graphene layers and eventual aggregation of the nanoparticles at moderate temperatures. A series of compositions with different weight ratios of ZnO nanoparticles were prepared and used as a reactive sorbent in low temperature hydrogen sulfide (H₂S) removal from natural gas. The composite sorbent having a ZnO mass ratio of 45.1 wt% showed a significantly greater H₂S adsorption capacity (3.46 mmol g⁻¹) than that of pure ZnO (1.06 mmol g⁻¹), indicating that hybridization of ZnO with grpahene significantly improved the H₂S removal ability. Such enhancement was mainly attributed to the higher surface area, greater pore volume and unique morphology at the nanoscale in the graphene–ZnO hybrid.