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Sulfur-resistant Mo-based catalysts have become promising for the one-step synthesis of methanethiol (CH3SH) from CO/H2/H2S, but the low reactant conversion and poor product selectivity have constrained its development. Herein, we synthesized K-MoS2/Al2O3 and K-Mo2C/Al2O3 catalysts via the sulfurization and carbonization of K-Mo-based catalysts in the oxidized state, respectively. During the synthesis of CH3SH, both K-Mo2C/Al2O3 and K-MoS2/Al2O3 showed excellent catalytic performance, and the activity of the former is superior to that of the latter. The effect of different treatments on the catalytic performance of Mo-based catalysts was investigated by XRD, BET, Raman spectroscopy, H2-TPR, and reactants-TPD characterization. The results showed that the sulfide-treated sample showed stronger metal-support interactions and contributed to the formation of K2S, which exposed more active sites and stabilized the formation of C-S bonds. Carbonized samples enhanced the activation of H2, which promoted the hydrogenation of the intermediate species of carbonyl sulfide (COS) and thus improved the selectivity of CH3SH. [ABSTRACT FROM AUTHOR]

The cooperative transition of sulfur-containing pollutants of H2S/CO/H2 to the high-value chemical methyl mercaptan (CH3SH) is catalyzed by Mo-based catalysts and has good application prospects. Herein, a series of Al2O3-supported molybdenum carbide catalysts with K doping (denoted herein as K-Mo2C/Al2O3) are fabricated by the impregnation method, with the carbonization process occurring under different atmospheres and different temperatures between 400 and 600 °C. The CH4-K-Mo2C/Al2O3 catalyst carbonized by CH4/H2 at 500 °C displays unprecedented performance in the synthesis of CH3SH from CO/H2S/H2, with 66.1% selectivity and a 0.2990 g·gcat−1·h−1 formation rate of CH3SH at 325 °C. H2 temperature-programmed reduction, temperature-programmed desorption, X-ray diffraction and Raman and BET analyses reveal that the CH4-K-Mo2C/Al2O3 catalyst contains more Mo coordinatively unsaturated surface sites that are responsible for promoting the adsorption of reactants and the desorption of intermediate products, thereby improving the selectivity towards and production of CH3SH. This study systematically investigates the effects of catalyst carbonization and passivation conditions on catalyst activity, conclusively demonstrating that Mo2C-based catalyst systems can be highly selective for producing CH3SH from CO/H2S/H2. [ABSTRACT FROM AUTHOR]

For high value-added utilization of carbide slag and sequestration of CO2, spherical vaterite was prepared at atmospheric pressure using carbide slag as raw material and various additives. The effects of additive types, reaction temperature, impurities in carbide slag and reaction system on vaterite in calcium carbonate synthesis were investigated by X-ray diffraction, scanning electron microscope and fourier transform infrared spectroscopy. The results show that glycine and serine have significant effect on the formation of vaterite. The increase of reaction temperature is not conducive to the formation of vaterite. The impurities Al2 O3 and SiO2 in carbide slag induce Ca(OH)2 mineralization CO2 system to form calcite. Different reaction systems affect the crystal size of prepared vaterite, and the crystal size prepared by carbide slag-CO2 system is the smallest. In the carbide slag-CO2 reaction system at 15 °C, monodisperse vaterite type CaCO3 with rough protrusions on the surface can be prepared by adding glycine. The above results provide a simple method for preparing high value-added vaterite from alkaline industrial wastes such as carbide slag, and safely and effectively storing a large amount of CO2 greenhouse gases. [ABSTRACT FROM AUTHOR]