钙钛矿型La_(2)NiB′O_(6)催化剂Ni和B′位点的协同效应及其对二氧化碳甲烷化性能的影响

Synergistic effect of Ni and B′ Sites on Perovskite type La_(2)NiB′O_(6)catalyst and its effect on catalytic performance for carbon dioxide methanation

钙钛矿型金属氧化物由于高的可逆储氧能力和结构稳定的特点,在催化领域被广泛应用。本文研究了钙钛矿型金属氧化物对于CO_(2)甲烷化的催化活性,通过溶胶凝胶法制备了LaNiO_(3)催化剂,同时用不同的元素B′(B′=Co,Mn,Fe)对Ni进行掺杂得到La_(2)NiB′O_(6)双钙钛矿,通过测试催化能力以研究不同金属间协同作用对催化效果的影响,利用XRD,BET,SEM和H_(2)-TPR等方法对制备的催化剂进行了一系列表征。结果显示,第二金属元素的加入没有改变原有的结构,将前驱体进行简单还原后,La_(2)NiB′O_(6)催化剂具有高的氧空位、较好的还原性、优异的Ni分散性,它取决于Ni-B′离子之间的协同作用。其中,La_(2)NiCoO_(6)催化剂在400℃表现出最佳的催化性能,转化率达91.3%,这归因于Co掺杂形成的双金属合金以及在3种催化剂中具有更高的氧空位,更好的还原性能和对CO_(2)更强的吸附性能,提供了更多的反应位点,从而增强了La_(2)NiCoO_(6)催化剂对CO_(2)甲烷化反应的催化活性。

In this paper,the catalytic activity of perovskite type metal oxides for CO_(2) methanation was investigated.LaNiO,catalyst was prepared by sol-gel method,and La_(2)NiB′O_(6)perovskite was obtained by doping Ni with different elements B′(B′=Co,Mn,Fe).The catalytic ability of different catalysts was tested to study the synergistic effect between different metals.Prepared catalysts were characterized using XRD,BET,SEM and H_(2)-TPR.The results indicate that the original structure remained unchanged despite the introduction of a second metal element.Reducing the precursor in a hydrogen atmosphere resulted in the formation of Laz O,from the A site of La,and the reduction of the B site to the corresponding metal ions.Due to the synergistic effect between different Ni-B′ions,the La_(2)NiB′O_(6)catalysts showed differences in oxygen vacancies,reducibility,and dispersion.Among them,the Ni-Fe ions increased the overall reduction resistance of the catalysts due to the high temperature stability of Fe.Conversely,The La_(2)NiCoO_(6) catalysts showed excellent performance in oxygen vacancy,reducibility and dispersibility,which enabled the catalysts to provide more reactive sites for the reaction and enhanced the adsorption performance of CO_(2),and thus strengthened the catalytic activity of La_(2)NiCoO_(6)catalysts in the methanation reaction of CO_(2).In performance test,La_(2)NiCoO_(6)achieved the highest conversion and selectivity,showing the best catalytic performance at 40o℃,with a conversion of 91.3%.