Investigation On Co-Mo/γ-Al₂O₃ Catalysts For Synthesis Of Ethyl Mercaptan

Ethyl mercaptan is an important organic intermediate, which has been widely used in synthesis of agrochemicals and pharmaceuticals. Synthesis of ethyl mercaptan from ethylene and hydrogen sulfide is a green synthesis route with 100% atom availability. A series of Co-Mo/γ-Al2O3 catalyst samples were prepared by the incipient-wetness impregnation method in this work, and characterized using the techniques of XRD,XPS,NH3-TPD,H2-TPR and the activity evaluation in fixed-bed micro-reactor techniques. The effects of preparation conditions and promoters on the structure of catalysts, the relationship between the structure of catalysts and their activity and selectivity were investigated, and the main possible reasons impacting the reactivity of catalysts were discussed.The addition of proper amount of Co promoter could result in the formation of easy reduced species on the surface of catalysts, and decrease the reduction temperature. The MoS2 slabs could be modified, and more borders and corners on surface wound formed, when the content of CoO reached to 10wt%, thus the catalytic performances were improved.The calcinations temperature could not only change the distribution and structure of active component, but also the acid strength on the surface of catalysts. The calcinations of catalyst at 550°C might promote the formation of"CoMoO4"phase which was the precursor of active Co-Mo-S structure, so the better catalytic performance was obtained.The addition of proper amount of K promoter would be beneficial to enhance the dispersivity of active components, and to promote the reduction of Mo compound. When the K2O content was 2wt%, the conversion of ethylene was 81.7%, and the selectivity of ethyl mercaptan was 61%.Under the reaction conditions of pressure 1.2MPa, GHSV of ethylene 300h-1 and molar ratio of hydrogen sulfide to ethylene 3:1 mol/mol, the Co-Mo/γ-Al2O3 catalyst sulfided at 270oC exhibited higher catalytic activity, the conversion of ethylene was 82.2%,and the selectivity of ethyl mercaptan was 77.9%.