Abstract:

MoO₃/ZrO₂ catalyst, which prepared by solution combustion method, achieved the highest CO methanation activity due to its high surface area and effective MoO₃ dispersion on ZrO₂ support. By study of sulfidation process on methanantion activity, it was found that sulfidation pressure, time and H₂S concentration had little effect but sulfidation temperature had significant effect. For one-step constant temperature sulfidation process, the optimum sulfidation temperature was 300℃. Catalyst characterization showed that isothermal sulfidation at 300℃ produced catalyst with complete sulfidation and many MoS₂ crystalline, which is helpful to improve methanation activity. Isothermal sulfidation below 300℃ yielded catalyst with incomplete sulfidation and fewer amounts of MoS₂ crystalline while isothermal sulfidation above 300℃ resulted aggregation of MoS₂ crystalline, which will deteriorate MoO₃/ZrO₂ catalyst. For stepwise sulfidation process, the optimum sulfidation temperature was 400℃, which resulted catalyst with nearly same methanation activity as that of one-step isothermal sulfidation at 300℃. Therefore, the suitable sulfidation condition for MoO₃/ZrO₂ catalyst is determined as 0.1 MPa, isothermal 300℃, 3% H₂S/H₂, and time 4 h.

Key words: low temperature, sulfur-resistant, catalyst, methane, CO, MoO₃

摘要：

采用燃烧法制备MoO₃/ZrO₂催化剂，该催化剂由于具有比表面积大、粒径小的优点，表现出很高的低温耐硫甲烷化活性。通过考察硫化工艺条件的影响发现，硫化过程中硫化时间、硫化压力、硫化氢浓度的影响不大，而硫化温度的影响较明显，300℃下恒温硫化效果最佳，表征结果表明，300℃下恒温硫化可以使催化剂完全硫化，得到较多的MoS₂晶格条纹，有利于提高催化剂的甲烷化活性。恒温硫化时，硫化温度低于300℃时，催化剂硫化不完全，形成的MoS₂晶格条纹较少；硫化温度过高会导致催化剂过度硫化并发生团聚，从而导致催化剂的耐硫甲烷化活性降低。分步硫化时目标温度为400℃时效果最佳，且与300℃恒温硫化的效果接近，对于MoO₃/ZrO₂催化剂，可选择300℃恒温硫化，适宜的硫化条件为：硫化压力0.1 MPa，硫化温度300℃，硫化氢浓度3% H₂S/H₂，硫化时间4 h。

关键词: 低温, 硫化, 催化剂, 甲烷, 一氧化碳, 氧化钼