Abstract: Ni-Mn/Al₂O₃ catalysts with different contents of Mn were prepared by co-impregnation method, and the catalytic performance for CO methanation in slurry-bed reactor was studied. The catalysts were characterized by XRD, H₂-TPR, BET, TEM and H₂-chemisorption. The addition of Mn promoted the dispersion of Ni species, weakened the interaction between Ni species and support, decreased the reduction temperature, increased the catalyst specific surface area and decreased the particle size of active metallic Ni. With the increase of Mn content, the catalytic performance of Ni-Mn/Al₂O₃ catalysts increased firstly and then decreased, and the catalyst Ni-Mn/Al₂O₃ with Mn content of 4% exhibited the best catalytic performance. Excess addition of Mn decreased catalytic performance, because the active component Ni was covered by Mn. The investigation on effects of reaction temperature and reaction pressure showed that under the reaction conditions of 280℃ and 1.5 MPa, conversion of CO and selectivity of CH₄ for the catalyst sample 16Ni4Mn/Al₂O₃ reached 96.2% and 88.8%, respectively.

Key words: slurry-bed reactor, syngas, methanation, natural gas, Ni-Mn/Al₂O₃ catalyst, manganese promoter

摘要： 采用共浸渍法制备了Ni-Mn/Al₂O₃催化剂，考察了助剂Mn的含量对催化剂结构及浆态床CO甲烷化性能的影响。采用XRD、H₂-TPR、BET、TEM、H₂-化学吸附等表征对催化剂进行了测试分析，结果表明，Mn助剂的引入能够促进Ni物种在载体表面的分散，减弱Ni物种与载体的相互作用，降低催化剂的还原温度，提高催化剂的比表面积，减小活性金属Ni的晶粒尺寸。随着Mn含量的增加，Ni-Mn/Al₂O₃催化剂的甲烷化性能先升后降，其中以Mn含量为4%（质量分数）时的催化甲烷化性能最佳，添加过量的Mn导致活性组分Ni被部分覆盖，催化甲烷化性能下降。通过对16Ni4Mn/Al₂O₃催化剂样品的浆态床反应温度及反应压力的研究发现，当反应温度为280℃、反应压力为1.5 MPa时，催化剂样品16Ni4Mn/Al₂O₃的CO转化率及CH₄选择性分别达到96.2%和88.8%。

关键词: 浆态床反应器, 合成气, 甲烷化, 天然气, Ni-Mn/Al₂O₃催化剂, Mn助剂