球状活性炭担载MnOx-CeO2和尿素的低温无氨脱硝行为研究

以MnO_x-CeO₂为活性组分、以尿素为还原剂，制备了球形活性炭（SAC）担载MnO_x-CeO₂和尿素的复合催化剂，利用扫描式电子显微镜-能谱仪（SEM-EDS）、X射线衍射（XRD）和低温N₂吸附-脱附等对催化剂的物理化学结构进行了表征，考察了该催化剂在低温（30-90 ℃）和没有氨气情况下对NO的选择性催化还原（SCR）性能。结果表明，在30-50 ℃的反应温度下，炭载体的微孔孔容仍是NO吸附与氧化的主要活性位点；而在70-90 ℃的反应温度下，锰铈金属氧化物成为NO吸附与氧化的主要活性位点，从而提高了催化剂的SCR反应活性。当反应温度为90 ℃、空速为6000 h^-1、NO和O₂浓度分别为0.05%和20%时，担载8% Mn （锰铈物质的量比为1∶1）和10%尿素的催化剂的MO_x稳态脱除率可达85.6%，实现了在低温、无氨状况下的高效脱硝。

Removal of NO at low temperature and in the absence of ammonia over spherical activated carbon loaded with MnOx-CeO2 and urea

A complex catalyst was prepared by loading MnO_x-CeO₂ and urea on spherical activated carbon (SAC) for the selective catalytic reduction (SCR) of NO at low temperature (30-90 ℃) in the absence of ammonia. The complex catalyst was characterized by scanning electron microscopy-energy dispersive spectrum (SEM-EDS), X-ray diffraction (XRD), and N₂ sorption. The results show that at 30-50 ℃, the micropores of SAC acts as the main active sites for NO adsorption and reaction, whereas at 70-90 ℃, MnO_x-CeO₂ turns to be the main active sites for NO adsorption and reaction; the urea-SCR activity is enhanced by MnO_x-CeO₂ in a wide temperature range. Over the complex catalyst loaded with 8% Mn (the mole ratio of Mn to Ce is 1) and 10% urea, the steady conversion of MO_x reaches 85.6% in the absence of ammonia, under the conditions of 90 ℃, 0.05% NO, 20% O₂ and a space velocity of 6000 h^-1.