添加氯离子对Ni/CeO2催化剂CO选择甲烷化反应催化性能的促进

采用浸渍方法制备NiO(Cl_x)/CeO₂系列样品,经还原后得到Ni(Cl_x)/CeO₂催化剂,用于富氢气体中CO的选择甲烷化反应,考察Cl/Ce原子比(x)对CO选择甲烷化反应活性的影响. 结果表明,添加氯离子能够显著抑制CO₂甲烷化反应,因而可使富氢气体中CO浓度降至10-5以下并且CO甲烷化反应选择性不低于50%,满足质子交换膜燃料电池对燃料的要求. 通过CO和CO₂吸附实验、程序升温还原(TPR)测定以及物相组成和晶粒尺寸分析,揭示添加氯离子的作用. 

Effect of Chlorine Doped in Ni/CeO2 Catalyst on Selective Methanation of CO in H2-Rich Gas

A series of 20%NiO(Cl_x)/CeO₂ samples with feed atomic ratio of Cl/Ce at x=0.0~0.30 were prepared by impregnation method and used to selective methanation of CO in H₂-rich gas (CO-SMET) after reduction. It is found that chlorine doped suppressed CO₂ conversion greatly. And CO concentration was thus decreased to below 10-5 over 20% Ni(Cl_0.2)/CeO₂ catalyst with CO methanation reaction selectivity not less than 50% in a wide reaction temperature range of 220~240 ℃, meeting the requirement for fuel of proton exchange membrane fuel cell (PEMFC). In order to reveal effect of chlorine doping, measurements of X-ray diffraction (XRD), temperature programmed reduction (TPR) and adsorption isotherms of CO and CO₂ were conducted. Phase composition of the samples and crystallite size of CeO₂ were estimated by the Rietveld method. Thickness of crystallites of NiO or Ni was estimated by the Scherrer equation.