Ni/MWCNT及镧改性Ni/MWCNT催化CO2甲烷化反应的性能

以多壁碳纳米管(MWCNT)为载体, 通过浸渍法制备了负载型镍催化剂和稀土镧改性的镍催化剂, 并对其二氧化碳甲烷化的催化性能进行了研究. 借助比表面积测试、程序升温还原(TPR)、X射线衍射(XRD)和X射线光电子能谱(XPS)等表征手段研究了稀土镧的添加对Ni/MWCNT催化剂结构和表面组成、催化剂还原性能以及CO₂甲烷化反应性能的影响. 结果表明: 稀土镧改性的Ni/MWCNT较Ni/MWCNT催化剂具有更好的CO₂甲烷化活性, 镧组分的加入提高了催化剂表面的镍物种浓度和分散度, 弱化了氧化镍与载体MWCNT之间的相互作用, 促进了氧化镍的还原, 同时提高了表面镍物种的电子密度, 增加了对反应物的吸附能力, 从而提高了其CO₂甲烷化活性. 制备过程中稀土镧的添加次序对催化性能有较明显的影响, 其活性顺序为先浸渍镧后浸渍镍制备的催化剂活性明显好于先浸渍镍后浸渍镧制备的催化剂.

Catalytic Properties of Ni/MWCNT and La-Promoted Ni/MWCNT for Methanation Reaction of Carbon Dioxide

Nickel multiwalled carbon nanotubes(Ni/MWCNT) and lanthanum-promoted Ni/MWCNT were successfully synthesized by impregnation.Methanation of carbon dioxide was used as a probe to evaluate their catalytic performance.N 2-BET,temperature programmed reduction(TPR),X-ray powder diffraction(XRD) and X-ray photoelectron spectroscopy(XPS) were used to study the advantageous effects of La on the structure,surface composition,reduction properties and reaction performance of Ni/MWCNT.It was found that La-promoted Ni/MWCNT catalysts showed better catalytic activity for the reaction than the un-promoted.The addition of La to Ni/MWCNT improves the concentration and dispersion of the active NiO component on the catalyst surface,thus weakening the interaction between support and NiO species,which in turn improves the electron density at the NiO species.As a consequence,the adsorption of reactants was enhanced and the activity improved.Moreover,the sequence in which La was added was also studied in this work.Ni-La/MWCNT,in which La was impregnated onto the MWCNT first,shows better catalytic performance than La-Ni/MWCNT,where the Ni was impregnated first.