载体酸碱性对高硫合成气制甲硫醇的K-Mo-Co催化剂结构和性能的影响

Effects of Acid-Base Properties of Supports on Structure and Activity of K-Mo-Co Catalysts for Synthesis of Methanethiol from High H_2S-Containing Syngas

选取3种酸碱性不同的载体(γ-Al2O3,SiO2,MgO)制备由高硫合成气制甲硫醇的负载型K-Mo-Co催化剂。它们的活性高低顺序为:K2MoCo0.35O/SiO2>K2MoCo0.35O/γ-Al2O3>K2MoCo0.35O/MgO;程序升温脱附表征结果显示,这3种不同载体的催化剂与载体的酸碱性强弱顺序一致,弱酸性载体制备的催化剂对合成甲硫醇有利;H2程序升温还原和激光Raman光谱表征结果显示,碱性载体制备的催化剂中,Mo以易于还原和硫化的八面体构型存在,硫化后主要以MoS2存在;弱酸性载体制备的催化剂中,Mo以难于还原和硫化的四面体构型存在,硫化后主要以氧硫钼物种存在,这些物种与合成甲硫醇密切相关。

K - Mo - Co catalysts for synthesis of methanethiol from high H2 S - containing syngas were prepared seperately using y - Al2O3, SiO2 and MgO as supports. The catalysts were characterized by means of NH3 -TPD, CO2 -TPD and laser Raman spectroscopy（LRS）. Activity of the catalysts in the synthesis of CH3SH is in order as follows： K2MoCo0.35 O/SiO2 〉 K2MoCo0.35 O/γ - Al2O3 〉 K2MoCo0.350/MgO. Acid-base properties of the catalysts are in accordance with those of supports. The catalyst prepared with weak acidic support is favorable to the synthesis of CH3 SH. Mo species in catalyst prepared with basic supports exist in form of octahedron, which is easy to be reduced and sulfided, and result in MoS2 becoming dominant species after sulfidation. Mo species in catalyst prepared with weak acidic support exist in form of tetrahedron, which is difficult to be reduced and sulfided. After sulfidation molybdenum oxysulfide species instead of MoS2 become the dominant species, which are closely related with formation of methanethiol.