原位漫反射红外光谱研究Ni-Fe/γ-Al2O3催化CO甲烷化反应  

Study on catalytic performance of Ni-Fe/γ-Al2O3 for CO methanation using in-situ diffuse reflectance infrared spectroscopy

作　　者：武瑞芳[1] 王宁[1] 周翔 王永钊[1] 赵永祥[1] Wu Ruifang;Wang Ning;Zhou Xiang;Wang Yongzhao;Zhao Yongxiang(Engineering Research Center of Ministry of Education for Fine Chemicals,School of Chemistry and Chemical Engineering,Shanxi University,Taiyuan 030006,Shanxi,China)

机构地区：[1]山西大学化学化工学院,精细化学品教育部工程研究中心,山西太原030006

出　　处：《工业催化》2020年第12期22-27,共6页Industrial Catalysis

基　　金：山西省自然科学基金(201801D121043);国家自然科学基金(21673132)。

摘　　要：利用原位漫反射红外光谱研究Ni/γ-Al2O3、Fe/γ-Al2O3和Ni-Fe/γ-Al2O3催化CO甲烷化反应。结果表明,CO和CO-H2混合气在Ni/γ-Al2O3和Ni-Fe/γ-Al2O3催化剂上均存在化学吸附,且Ni-Fe/γ-Al2O3对CO和CO-H2混合气的吸附能力明显强于Ni/γ-Al2O3催化剂,但在Fe/γ-Al2O3上未发生化学吸附。CO-H2混合气吸附时,Ni/γ-Al2O3表面以镍羰基氢化物吸附为主,而Ni-Fe/γ-Al2O3表面则以镍多氢羰基氢化物为主,特别是桥式镍多氢羰基氢化物。与镍羰基氢化物相比,镍多氢羰基氢化物结构中含有更多的氢原子,其较强的给电子作用提高了Ni中心对CO分子反键π轨道反馈电子的能力,导致Ni-C键增强,C-O键削弱。因此,与Ni/γ-Al2O3催化剂相比,Ni-Fe/γ-Al2O3催化剂上CO分子的C-O键更易断裂进而加氢进行甲烷化反应,推测这是Ni-Fe/γ-Al2O3催化剂表现出更高催化活性的直接原因。The catalytic performances of Ni/γ-Al2O3,Fe/γ-Al2O3 and Ni-Fe/γ-Al2O3 for CO methanation were studied by in-situ diffuse reflectance infrared spectroscopy.Results show that CO and CO-H2 mixed gas exhibit chemical adsorption on both Ni/γ-Al2O3 and Ni-Fe/γ-Al2O3 catalysts,and the adsorption capacity of Ni-Fe/γ-Al2O3 for CO and CO-H2 mixed gas is significantly stronger than that of Ni/γ-Al2O3,yet no chemical adsorption occurs on Fe/γ-Al2O3.When CO-H2 mixed gas is adsorbed,nickel carbonyl hydride exists on the surface of Ni/γ-Al2O3,while nickel multihydrogen carbonyl hydride,especially bridged nickel multihydrogen carbonyl hydride exists on the surface of Ni-Fe/γ-Al2O3.Compared with nickel carbonyl hydride,nickel multihydrogen carbonyl hydride contains more hydrogen atoms,whose stronger electron-donating property improves the ability of the Ni atom for feeding back electrons to the anti-bondedπorbital of CO molecular,resulting in that the Ni-C bond becomes stronger,and the C-O bond becomes weaker.Therefore,the C-O bond of CO molecular on the Ni-Fe/γ-Al2O3 catalyst breaks more easily and is hydrogenated to methane comparing with the Ni/γ-Al2O3 catalyst,which may be the direct reason why the Ni-Fe/γ-Al2O3 catalyst shows higher catalytic activity.

关 键 词：催化化学 CO甲烷化 原位漫反射红外光谱 Ni/γ-Al2O3 Ni-Fe/γ-Al2O3 羰基氢化物 

分 类 号：TM911.4[电气工程—电力电子与电力传动] O643.36[理学—物理化学]