Fei Wang,Zhibo Xie,Jinsheng Liang,Baizeng Fang,Yu’ang Piao,Ming Hao,Zishuo Wang
Low temperature NH3 selective catalytic reduction (NH3-SCR) technology is an efficient and economical strategy for cutting NOx emissions from power-generating equipment. In this study, a novel and highly efficient NH3-SCR catalyst, tourmaline-modified FeMnTiOx is presented, which was synthesized by a simple one-step sol–gel method. We found that the amount of tourmaline has an important impact on the catalytic performance of the modified FeMnTiOx-based catalysts, and the NOx conversion exceeded 80% from 160 to 380 °C with the addition of 5 wt % tourmaline. Compared with the pure FeMnTiOx, the catalytic efficiency at a temperature below 100 °C was increased by nearly 18.9%, and the operation temperature window was broadened significantly. The enhanced catalytic performance of the FeMnTiOx catalyst was mainly attributed to the small spherical nanoparticles structure around the tourmaline powders, resulting in the increased content of Mn3+, Mn4+, and chemical oxygen on the catalytic surface. These as-developed tourmaline-modified FeMnTiOx materials have been demonstrated to be promising as a new type highly efficient low temperature NH3-SCR catalyst.
To clarify the role of metal dopants in low-temperature NH3-SCR of NO, FeMnTiOxcatalysts were synthesized by coprecipitation and separately modified with Ce, Co, or W. The catalysts were evaluated for NO conversion, separate O2/H2O switching response and dry-feed time-on-stream stability and characterized by XRD, SEM, N2adsorption–desorption, XPS, H2-TPR and NH3-TPD. Ce doping at Ce/Mn = 0.3 suppressed TiO2crystallization, increased the BET surface area from 136 to 231 m2g−1and the pore volume from 0.19 to 0.58 cm3g−1, raised the Mn4+/Mn3+ratio from 0.70 to 1.25, and increased the medium-strong-acid relative peak area from 555.4 to 1293.2 a.u. FeMnCe0.3TiOxmaintained at least 90% NO conversion from 140 to 360 °C, gave 75% conversion at 400 °C, and averaged 97.4% during a 40 h dry-feed test at 350 °C. The results show that the superior Ce-modified catalyst arises from the combined regulation of texture, surface redox balance and acidity.
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