A Sulfur Emission-Free Route for the Synthesis of Mo and Mo₂C via Carbothermal Reduction of MoS₂

In this work, the sulfur-free emission route for the synthesis of Mo and Mo₂C via carbothermal reduction of MoS₂ was proposed. The internal MoS₂-C mixture is wrapped by an external desulfurization layer composed of CaO and C. In the internal layer, MoS₂ reacted with carbon black and generated Mo, Mo₂C (or their mixture), as well as S₂, CS₂ and CS gas. Both experiments and thermodynamic calculations show that the main gaseous product should be CS₂. The sulfur-containing gas produced can be completely captured by the desulfurization layer in the form of CaS. This strategy can avoid the emission of S-containing gas compared with the traditional route. In addition, after removing the unreacted desulfurizer and gently breaking the desulfurization product layer, the molybdenum-containing product can be collected. For the raw material with a MoS₂:C molar ratio of 1:1, after reacting at 1600 °C for 4 hours, Mo with carbon and sulfur contents of 0.053 and 0.050 pct is acquired. In addition, Mo₂C-dominant product can be obtained after reacting at 1600 °C for 4 hours at a MoS₂:C molar ratio of 1:1.52, with the carbon and sulfur contents of 5.878 and 0.049 pct. The above shows that this strategy has the advantages of high-efficiency desulfurization and simple separation of desulfurization product, which is an environment-friendly method for the production of molybdenum additives.