催化剂表面Cu0含量对二氧化碳加氢合成C2+醇性能的影响

通过在空气气氛下焙烧Cu@Fe-MIL-88B MOF材料制备了CuFe组分均匀分散的催化剂前驱物, 该前驱物经过不同温度下的预还原制得表面具有不同Cu和Fe价态分布的系列催化剂. 将所制备的催化剂用于固定床反应器上CO₂加氢合成C₂₊醇的性能研究, 并结合催化剂的X射线衍射(XRD)、 X射线光电子能谱(XPS)、 氢气程序升温还原(H₂-TPR)、 氮气吸附-脱附、 扫描电子显微镜(SEM) 和高分辨率透射电子显微镜(HRTEM)等表征结果发现, 较高的还原温度增加了催化剂表面低价态的Cu和Fe的含量; 当还原温度为350 ℃时, 催化剂表面Cu⁰/(Cu⁺+Cu⁰)摩尔比为73.9%, 单质Fe摩尔分数为0.40%, 催化效果最好, CO₂转化率达到6.82%, 总醇选择性为39.4%, 其中C₂₊醇的摩尔比达到95.1%.

Effect of Surface Cu0 Content of the Catalysts on CO2 Hydrogenation to C2+ Alcohols †

Pyrolyzing metal organic framework(MOF) material Fe-MIL-88B loaded with Cu in air atmosphere, uniformly dispersed CuFe based catalysts with different Cu and Fe valence distribution were gained at different reduction temperatures. The structure of the catalysts were characterized by means of X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), H₂ temperature program reduction(H₂-TPR), N₂ adsorption-desorption(BET), scanning electron microscopy(SEM), and high resolution transmission electron microscopy(HRTEM). The catalytic performances of CO₂ hydrogenation to C₂₊ alcohols were investigated on a fixed-bed reactor. It was found that the higher the reduction temperature was, the more percentage of Cu and Fe with lower valence state was on the surface of the catalysts. When the reduction temperature was 350 ℃, Cu⁰/(Cu⁺+Cu⁰) was 73.9 %, and 0.4% Fe ⁰ appeared, the catalytic performance was the best, where the CO₂ conversion rate was 6.82%, the total alcohol selectivity was 39.4%, and the molar percentage of C₂₊ alcohol was 95.1%.