Solid-phase hydrogen in a magnesium–carbon composite for efficient hydrogenation of carbon disulfide

Abstract

Desulfurization of syngas from coal gasification is an essential process in chemical synthesis to achieve high value-added utilization of coal. The hydrogenation conversion method is known for its high desulfurization degree in organic sulfur removal, but it is hindered by severe operating conditions, which leads to low safety and low efficiency. A Mg–carbon composite is synthesized by a reactive ball-milling method to store solid-phase hydrogen with high activity for CS₂ hydrogenation. Without the presence of high-pressure gaseous hydrogen, CS₂ in the stream is hydrogenated by the composite at 250 °C to yield CH₄ and H₂S, and the conversion achieved is over 91.8% in 300 min. First-principles calculations reveal that chemisorption structures can influence the reaction of CS₂ with MgH₂, in which horizontal chemisorption is in favor of the generation of gaseous H₂S while vertical chemisorption can result in solid MgS. This new method of hydrogenation paves the way for organic sulfur compound removal at moderate temperatures without using a high-pressure hydrogen atmosphere.