CO_2加氢合成甲醇的超细Cu-ZnO-ZrO_2催化剂的表征

Characterization of Ultrafine Cu-ZnO-ZrO_2 Catalysts for Methanol Synthesis via CO_2 Hydrogenation

采用原位顺磁共振 (EPR)、原位X射线光电子能谱 (XPS)和程序升温还原 (TPR)等手段 ,对CO2 加氢合成甲醇用的不同粒度的超细Cu ZnO ZrO2 催化剂各组分的相互作用进行了研究 .结果表明 ,ZrO2 的加入改变了催化剂的表面结构和配位状态 ,增加了活性组分的分散度 ,提高了催化剂的稳定性 .实验还发现 ,催化剂的粒度对各组分的相互作用有着重大的影响 ,催化剂的粒度较小时 ,Cu2 +主要以团簇的形式存在 ,易于被还原 ;催化剂的粒度较大时 ,Cu2 +主要以高度分散的形式存在 ,Cu在ZnO和ZrO2 中分布得更均匀 ,它们之间的相互作用更强 ,难于被还原 .TPR的实验结果也得到了一致的结论 .研究还认为 ,合成甲醇的活性中心是高分散的金属铜的团簇 ,而不是孤立的铜原子 .

Ultrafine Cu ZnO ZrO 2 catalysts for methanol synthesis via CO 2 hydrogenation were characterized by in situ electron paramagnetic resonance (EPR), in situ X ray photoelectron spectroscopy (XPS) and atomic emission spectrometry (AES), and temperature programmed reduction (TPR). The results show that the addition of ZrO 2 promoted the dispersion of the catalysts remarkably, and changed the surface construction and coordination. The particle size of the catalysts has great influence on the interaction of the catalyst components. When the particle size is small, Cu 2+ exists as cluster, and is easily to be reduced. When the particle size is large, Cu 2+ is more likely to exist as isolated atom distributing among ZnO and ZrO 2. The clusters of Cu, rather than isolated Cu, are evidenced to be the active centers for methanol synthesis via CO 2 hydrogenation.