掺加Nd和K改性对Co3O4催化分解N2O活性的影响

用水热法和共沉淀法分别制备了Nd-Co₃O₄催化剂，催化分解N₂O。其中，水热法制备的Nd-Co₃O₄催化活性较高。在不同组成的Nd-Co₃O₄中，优化出了较高活性的0.01Nd-Co₃O₄催化剂，在其表面浸渍K₂CO₃溶液制备K改性催化剂（K/Nd-Co₃O₄）。用X射线衍射（XRD）、N₂物理吸附、扫描电镜（SEM）、X射线光电子谱（XPS）、程序升温还原（H₂-TPR）、O₂程序升温脱附（O₂-TPD）等技术表征催化剂结构。结果表明，Nd-Co₃O₄和K改性催化剂均为尖晶石结构；K改性弱化了催化剂表面Co-O键，有利于表面氧的脱除，提高了催化剂活性。有氧有水气氛350 ℃连续反应40 h，K/Nd-Co₃O₄催化剂上的N₂O分解率超过90%，稳定性较好。

Effect of Nd-incorporation and K-modification on catalytic performance of Co3O4 for N2O decomposition

Nd-Co₃O₄ catalysts were prepared by hydrothermal and co-precipitation methods to catalyze the decomposition of N₂O. The catalysts prepared by hydrothermal method showed higher activity. Among the hydrothermal Nd-Co₃O₄ catalysts, the catalyst with Nd/Co molar ratio of 0.01 had higher activity. 0.01Nd-Co₃O₄ catalyst was then impregnated by K₂CO₃ solution to prepare K-modified catalyst. The catalysts were characterized by means of X-ray diffraction (XRD), nitrogen physisorption, scanning electrons microscopy (SEM), X-ray photoelectron spectroscopy (XPS), hydrogen temperature-programmed reduction (H₂-TPR), and oxygen temperature-programmed desorption (O₂-TPD). The results show that Nd-Co₃O₄ and K-modified catalysts exhibit spinel structure. In contrast to bare Nd-Co₃O₄, the K-modified catalyst with higher activity is due to its weaker strength of Co-O bond and easier desorption of surface oxygen species. In addition, over 90% conversion of N₂O can be reached over 0.02K/0.01Nd-Co₃O₄ at 350 ℃ for 40 h under the co-presence of oxygen and steam in feed gases.