新型合成气甲烷化催化剂La2O3-ZrO2-Ni/Al2O3的制备与性能

针对常规合成气甲烷化催化剂高热结构稳定性差、活性低、适应性差等不足，本文创新地引用稀土金属氧化物La₂O₃复配过渡金属氧化物ZrO₂作为多功能复合助剂，利用反向沉淀法制备了新型合成气甲烷化催化剂La₂O₃-ZrO₂-Ni/Al₂O₃，同时制备催化剂Cr₂O₃-Ni/Al₂O₃作为参照组。采用X射线衍射（XRD）、透射电子显微镜（TEM）表征了催化剂的微观结构，并利用N₂吸附仪（BET）测量催化剂经高温水热处理前后的微孔结构参数，以考察催化剂的高热结构稳定性。结合国内某大型煤制天然气项目工艺特征和运行实践，应用Aspen Plus软件模拟了四段甲烷化工艺理论平衡值。基于自主固定床合成气甲烷化评价实验装置，考察了反应压力、空速和原料气H₂O(g)含量等因素对La₂O₃-ZrO₂-Ni/Al₂O₃催化性能的影响，并开展了1000h长周期寿命评价实验。结果表明，La₂O₃-ZrO₂-Ni/Al₂O₃比Cr₂O₃-Ni/Al₂O₃具有更优的高热结构稳定性；可使CO和CO₂反应达到或接近催化剂床层出口温度下的理论平衡状态，呈现显著的宽温活性；活性组分NiO晶粒尺寸介于7~10nm，分散度较高；对反应压力、空速和原料气H₂O(g)含量的变化不敏感，具有良好的操作弹性；1000h反应后仍能保持较高的活性和稳定性。

Preparation of a novel catalyst of La2O3-ZrO2-Ni /Al2O3 and its performance in syngas methanation

To overcome the limit of syngas methanation catalyst in thermal stability, activity or suitability, a novel catalyst, La₂O₃-ZrO₂-Ni/Al₂O₃, was prepared using La₂O₃ and ZrO₂ as multi-functional additive. Meanwhile, another catalyst of Cr₂O₃-Ni/Al₂O₃, was also prepared for reference. Then the microstructure of the catalyst was characterized by using X-ray diffraction (XRD) and transmission electron microscope (TEM). The micropore parameters were determined by using N₂-adsorption (BET) method. And the theoretical equilibrium values of the four-stage methanation process adopted by a certain SNG plant were simulated by using Aspen Plus. Furthermore, the influence of pressure, space velocity and H₂O(g) content on the catalyst performance were investigated, and the 1000h life assessment was also conducted. The results show that La₂O₃-ZrO₂-Ni/Al₂O₃ is superior to Cr₂O₃-Ni/Al₂O₃ in thermal stability and temperature activity, which helps the conversion of CO and CO₂ approaching to the simulated equilibrium values. The active component, NiO, is well dispersed, with the particle sizes in the range of 7-10nm. The performance of La₂O₃-ZrO₂-Ni/Al₂O₃ is insensitive to the changes of pressure, space velocity or H₂O(g) content. Moreover, La₂O₃-ZrO₂-Ni/Al₂O₃ could preserve its high activity and stability after running for 1000h.