Ce含量对Ni-Ce/Al_2O_3催化剂结构及浆态床CO甲烷化性能的影响

以γ-Al2O3为载体,采用等体积浸渍法制备了不同Ce含量的Ni-Ce/Al2O3催化剂,并考察了其浆态床CO甲烷化反应性能。借助XRD、BET、H2-TPR及CO-TPD等对催化剂进行了表征分析,研究了催化剂的微观结构与甲烷化性能之间的关系。结果表明,助剂Ce的引入能够加强Ni物种与载体之间的相互作用、增强活性组分Ni对CO的吸附能力。随着Ce含量的升高,Ni物种在载体表面的分散度提高、Ni晶粒粒径减小,催化剂的比表面积及与载体相互作用较强的β-NiO相对含量先升后降。催化剂的浆态床甲烷化活性随Ce含量的升高呈现规律性的变化,CO转化率和CH4时空收率先增加后略有下降,当Ce含量为4%(质量分数)时,催化剂甲烷化活性最佳。

Effect of Ce content of Ni-Ce/Al2O3 catalyst on structure and CO methanation in slurry-bed reactor

Ni-Ce/Al₂O₃ catalysts with different Ce contents were prepared by wet impregnation method using γ-Al₂O₃ as support, and their catalytic performance of CO methanation in slurry-bed reactor were evaluated. The catalysts were characterized with XRD, BET, H₂-TPR, CO-TPD, and the relationship between the microstructural properties of catalysts and CO methanation in slurry-bed reactor was investigated. The results indicated that the addition of Ce into Ni/Al₂O₃ catalyst strengthened the interaction between Ni species and the support and enhanced the CO adsorption. With the increase of Ce content, the dispersion of Ni species on support was improved, the particle size of nickel decreased, the specific surface area and the relative content of β-NiO with stronger interaction with support increased firstly and then decreased. The catalytic performance of CO methanation in slurry-bed changed regularly with the increase of Ce content, the conversion of CO and the space-time yield (STY) of CH₄ were all increased firstly and then decreased slightly. When the content of Ce reached 4%, the catalyst exhibited the best catalytic performance.