添加碱金属对甲烷与空气制合成气的催化剂性能的影响

Effect of Alkaline Metal Promoters on Properties of Ni/CaO-Al_2O_3 Catalyst for the Reaction of Methane with Air

考察了添加在镍基催化剂中的碱金属助剂 ,对甲烷与空气制合成气的催化反应性能的影响 ;并用 TPO、TPR、CO2 程序升温脱附 (TPD)、XPS及 CO脉冲色谱技术 ,对催化剂进行了表征 .实验表明 ,碱金属助剂对降低催化剂结炭有一定的作用 ,催化剂的抗积炭性能为 Ni- K2 O/Ca O- Al2 O3>Ni- L i2 O/Ca O- Al2 O3>Ni- Na2 O/Ca O-Al2 O3>Ni/Ca O- Al2 O3.在实验中发现 ,碱金属的添加 ,可使催化剂的 Ni比表面积变小、吸附 CO2 的能力增强 ,且结合能可发生不同程度的改变 .从而解释了碱土金属助剂对催化剂活性和抗积炭性的影响 .实验显示 ,Ni-L i2 O/Ca O- Al2

This article mainly is concerned with the influence of alkaline metal promoters on Ni based catalyst for catalytic oxidation of methane with air to syngas. These catalysts promoted by alkaline metal were investigated using TPO, CO\-2 TPD, XPS and CO pulse chromatograph. It is found that the alkaline metal promoter is effective in suppression of the formation of carbon deposition on catalyst. The abilities of resistance to carbon deposition are ordered as follows: Ni K\-2O/CaO Al 2O 3>Ni Li 2O/CaO Al 2O 3>Ni Na\-2O/CaO Al 2O 3>Ni/CaO Al 2O 3. It is also found that Ni crystal sizes in catalyst are enlarged, and the abilities of CO\-2 adsorption are strengthened. The binding energies of Ni2p\-\{3/2\} are changed by the addition of various alkaline metal promoters. The catalyst Ni Li 2O/CaO Al 2O 3 has not only higher activity and selectivity, but also better resistance to carbon deposition. The experimental results were discussed in different aspects.