Dong Anqi, Yang Zhi, Wang Weichao
Integrated Circuits and Smart System Lab (Shenzhen), Renewable Energy Conversion and Storage Center, Tianjin Key Laboratory of Photo-Electronic Thin Film Device and Technology, College of Electronic Information and Optical Engineering, Nankai University, Tianjin 300071, China.
ACS Omega. 2022 Mar 4;7(10):8633-8639. doi: 10.1021/acsomega.1c06648. eCollection 2022 Mar 15.
Low-temperature selective catalytic oxidation (SCO) is crucial for removing the NH slip from the upstream of NH-selective catalytic reduction (NH-SCR). Herein, combining zeolite Cu-SAPO34 and the active oxidant mullite SmMnO, we developed mixed-phase catalysts SmMnO/Cu-SAPO34 by grinding powder mixtures to achieve a low-temperature activity and a reasonable N selectivity. The physicochemical properties of the catalysts were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) measurement, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The evaluation of NH oxidation activity showed that for 30 wt % SmMnO/Cu-SAPO34, 90% NH conversion was at a temperature of 215 °C in the presence of 500 ppm NH and 21% O balanced with N. The in situ DRIFTS spectra reveal the internal SCR mechanism (i-SCR), i.e., NH oxidizing to NO on mullite and NO subsequently to proceed with SCR reactions, leading to higher conversion and selectivity over the mixed catalysts. This work provides a strategy to design the compound catalyst to achieve low-temperature NH oxidation via synergistic utilization of the advantages of each individual catalyst.
低温选择性催化氧化（SCO）对于去除氨选择性催化还原（NH-SCR）上游的氨逃逸至关重要。在此，我们将沸石Cu-SAPO34与活性氧化剂莫来石SmMnO相结合，通过研磨粉末混合物开发了混合相催化剂SmMnO/Cu-SAPO34，以实现低温活性和合理的氮选择性。通过X射线衍射（XRD）、布鲁诺尔-埃米特-泰勒（BET）测量、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、X射线光电子能谱（XPS）和原位漫反射红外傅里叶变换光谱（DRIFTS）对催化剂的物理化学性质进行了表征。氨氧化活性评估表明，对于30 wt%的SmMnO/Cu-SAPO34，在500 ppm氨和与氮气平衡的21%氧气存在下，90%的氨转化率在215°C的温度下实现。原位DRIFTS光谱揭示了内部选择性催化还原（i-SCR）机制，即氨在莫来石上氧化为一氧化氮，随后一氧化氮继续进行SCR反应，从而使混合催化剂具有更高的转化率和选择性。这项工作提供了一种设计复合催化剂的策略，通过协同利用每种催化剂的优势来实现低温氨氧化。
