La and Co Addition to Mn/TiO2 Catalysts for Enhancing Low-Temperature Denitrification Activity and H2O/SO2 Tolerance

• Published in: Industrial & engineering chemistry research 2023-11, Vol.62 (44), p.18303-18311
• Main Authors: Wang, Yan, Xie, Huidong, Liu, Hu, Mu, Ge, Yang, Chang, Chai, Shouning
• Format: Article
• Language: English
• Subjects: Kinetics, Catalysis, and Reaction Engineering
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/acs.iecr.3c01971

Manganese oxide-based denitrification catalysts supported by anatase with active components of Mn, Mn–La, Mn–Co, and Mn–La–Co oxides were prepared by a coprecipitation approach, and comparisons of their catalytic activities were made. The influences of Co and La addition on the NO removal and H2O/SO2 tolerance of the MnO x catalysts were investigated. The reasons for the different catalytic performances were investigated by using XRD, XPS, H2-TPR, and NH3-TPD experiments. The reaction mechanism of selective catalytic reduction of NO x with ammonia was determined by in situ diffuse reflectance infrared Fourier transform spectroscopy. Experiments proved that the addition of Co and La expanded the active temperature window (120–369 °C) and improved the sulfur tolerance due to the increase in the contents of Mn4+ and surface-active oxygen, along with the enhancement of the redox capacity of the catalyst. Different NH3–SCR reaction mechanisms were found over the catalysts Mn–La–Co/TiO2 and Mn/TiO2: the former was both the Eley–Rideal and Langmuir–Hinshelwood mechanisms, while the latter followed only the Langmuir–Hinshelwood mechanism. In addition, a “fast SCR” reaction mechanism was active for all catalysts. This work provides useful insights for improving the sulfur tolerance of manganese-based denitrification catalysts.