Sulfur-Emission-Free Process of Molybdenum Carbide Synthesis by Lime-Enhanced Molybdenum Disulfide Reduction with Methane

• Published in: Industrial & engineering chemistry research 2011-12, Vol.50 (23), p.13340-13346
• Main Authors: Ghasemi, Samad, Abbasi, Mohammad Hasan, Saidi, Ali, Kim, Jae Yul, Lee, Jae Sung
• Format: Article
• Language: English
• Subjects: Applied sciences; Carbon; Chemical engineering; Exact sciences and technology; Kinetics, Catalysis, and Reaction Engineering; Methane; Molybdenum carbides; Molybdenum disulfide; Pathways; Reaction time; Reduction; Synthesis
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/ie201860h

To investigate a sulfur-emission-free process of molybdenum carbide synthesis from molybdenite, the reaction pathways of MoS2 reduction with methane in the presence of lime (CaO) have been studied. A mixture of MoS2 + 2CaO was reduced isothermally with CH4 in a microreactor, and the composition of effluent gases and the reduced fraction were determined as a function of reaction time. Analysis of the solid phase at different reaction times at 800 °C showed the formation of CaMoO4 as an intermediate phase. Hence, the reaction pathways proposed for reduction of MoS2 + CaO with CH4 involves the direct reduction of MoS2 with CH4 to form Mo2C and sulfur-containing gases. The sulfur-containing gases are captured by CaO to form CaS, CO(g), CO2(g), and H2O(g). The unreacted MoS2 is oxidized by CO2(g) and H2O(g) to form MoO3(g), which reacted with CaO to form CaMoO4 on CaO particles. Finally, CaMoO4 and remaining MoS2 are further reduced with CH4. Characterization of solid samples was carried out by XRD, CHN, and FE-SEM equipped with EDS, providing results consistent with the proposed reaction pathways. Carbon content of solid sample increased with reduction time, and in fully reduced sample at 800 °C it was well above the stoichiometric amount indicating considerable excess carbon deposition due to CH4 cracking.