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Impacts of La addition on formation of the reaction intermediates over alumina and silica supported nickel catalysts in methanation of CO2
Journal of the Energy Institute ( IF 5.6 ) Pub Date : 2019-05-28 , DOI: 10.1016/j.joei.2019.05.009
Chuanfei Liang , Tao Wei , Hui Wang , Zhengjie Yu , Dehua Dong , Shu Zhang , Qing Liu , Guangzhi Hu , Xun Hu

This study aimed to investigate impacts of Al2O3 and SiO2, the supports of Ni catalysts with distinct properties, and the additive of La on catalytic behaviors and reaction intermediates formed during methanation of CO2. The results showed that the addition of La to either Ni/Al2O3 or Ni/SiO2 led to the reduced size of metallic nickel, the reduced reduction degree of nickel oxide, the increased alkalinity number and the increased activity for methanation of CO2. Furthermore, the addition of La to the Ni/SiO2 catalyst could suppress the formation of CO via the reverse water gas shift (RWGS) reaction. Ni/SiO2 was much more active than the Ni/Al2O3, even though nickel size was much bigger. The in situ Diffuse Reflection Infrared Fourier Transform Spectroscopy (DRIFTS) studies showed that the addition of La to Ni/Al2O3 interfered with integration of hydroxyl group with *CO2 species and formation of the bicarbonate and carbonate, while favored formation of the formate specie, enhancing the catalytic activity. For Ni/SiO2, instead of formate, CO* became the main reaction intermediate. The strong absorption of CO* favored its further conversion and explained the low selectivity of the silica-based catalysts toward CO. The addition of La to Ni/SiO2 catalyst facilitated further hydrogenation of CO* species to CH4 and promoted the catalytic activity.



中文翻译:

La的添加对CO 2甲烷化中氧化铝和二氧化硅负载的镍催化剂上反应中间体形成的影响

这项研究旨在研究Al 2 O 3和SiO 2,具有不同性能的Ni催化剂的载体以及La的添加对CO 2甲烷化过程中形成的催化行为和反应中间体的影响。结果表明,将La添加到Ni / Al 2 O 3或Ni / SiO 2中导致金属镍的尺寸减小,氧化镍的还原度减小,碱度数增加和CO的甲烷化活性增加。2。此外,将La添加到Ni / SiO 2催化剂中可以通过逆水煤气变换(RWGS)反应抑制CO的形成。镍/二氧化硅2比的Ni / Al的活性高得多2 ö 3,即使镍大小是大得多。原位漫反射红外傅里叶变换光谱(DRIFTS)研究表明,向Ni / Al 2 O 3中添加La会干扰羟基与* CO 2的结合以及碳酸氢盐和碳酸盐的形成,同时有利于碳酸氢盐和碳酸氢盐的形成。甲酸盐,增强催化活性。对于Ni / SiO 2,代替甲酸酯,CO *成为主要的反应中间体。CO *的强吸收有助于其进一步转化,并解释了二氧化硅基催化剂对CO的选择性低。向Ni / SiO 2中添加La催化剂促进了CO *物种进一步加氢成CH 4并提高了催化活性。

更新日期:2019-05-28
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