球状活性炭担载MnOx-CeO2和尿素的低温无氨脱硝行为研究

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

  • 摘要: 以MnOx-CeO2为活性组分、以尿素为还原剂,制备了球形活性炭(SAC)担载MnOx-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MOx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。

     

    Abstract: A complex catalyst was prepared by loading MnOx-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 ℃, MnOx-CeO2 turns to be the main active sites for NO adsorption and reaction; the urea-SCR activity is enhanced by MnOx-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 MOx 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.

     

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