Effects of Adding CeO2 to Ag/Al2O3 Catalyst for Ammonia Oxidation at Low Temperatures

The effects of adding CeO2 to Ag/Al2O3 on the selective catalytic oxidation of ammonia to nitrogen were investigated by activity test and N2 physisorption, X-ray diffraction, X-ray photoelectron spectroscopy, UV-Vis diffuse-reflectance spectroscopy, high resolution transmission electron microscopy, in situ diffuse reflectance infrared Fourier transform spectroscopy of NH3 adsorption, and O2-pulse adsorption. Adding a suitable amount of CeO2 improved the catalytic activity of Ag/Al2O3 for NH3 oxidation at temperatures below 160 °C, and slightly influenced N2 selectivity by improving the catalyst's ability to adsorb and activate O2 and the adsorption and activation of NH3.

摘要摘要：采用活性测试和氮气吸附、X 射线衍射、X 射线光电子能谱、紫外-可见漫反射吸收光谱、高倍透射电镜、原位漫反射傅里叶变换红外光谱和 O2 脉冲吸附等研究了铈添加对 Ag/Al2O3 催化剂低温氨氧化性能的影响. 结果表明, 适量铈的添加可以明显促进 Ag/Al2O3 催化剂的低温氨氧化活性, 且对催化剂的选择性影响不大. 添加铈不仅可以促进 Ag/Al2O3 催化剂表面吸附和活化 O2 的能力, 而且可促进催化剂表面对氨的解离吸附和活化. 这是铈促进 Ag/Al2O3 催化剂低温氨氧化活性的主要原因.

Graphical abstractAdding CeO2 to Ag/Al2O3 enhanced O2 uptake and promoted the dissociative adsorption of NH3 to -NH2 and -NH, which improved the selective catalytic oxidation of ammonia at low temperatures.Figure optionsDownload full-size imageDownload as PowerPoint slide