Manganese-rich MnSAPO-34 molecular sieves as an efficient catalyst for the selective catalytic reduction of NO x with NH3: one-pot synthesis, catalytic performance, and characterization

Fabrication of a wide temperature Mn–Ce/TNU-9 catalyst with superior NH3-SCR activity and strong SO2 and H2O tolerance

A Mn–Ce/TNU-9 catalyst demonstrated excellent sulfur and water resistance and good catalytic stability in the NH₃-SCR reaction.

DeNOx of Nano-Catalyst of Selective Catalytic Reduction Using Active Carbon Loading MnOx-Cu at Low Temperature

With the improvement of environmental protection standards, selective catalytic reduction (SCR) has become the mainstream technology of flue gas deNOx. Especially, the low-temperature SCR nano-catalyst has attracted more and more attention at home and abroad because of its potential performance and economy in industrial applications. In this paper, low-temperature SCR catalysts were prepared using the activated carbon loading MnOx-Cu. Then, the catalysts were packed into the fiedbed stainless steel micro-reactor to evaluate the selective catalytic reduction of NO performance. The influence of reaction conditions was investigated on the catalytic reaction, including the MnOx-Cu loading amount, calcination and reaction temperature, etc. The experimental results indicate that SCR catalysts show the highest catalytic activity for NO conversion when the calcination temperature is 350 °C, MnOx loading amount is 5%, Cu loading amount is 3%, and reaction temperature is 200 °C. Under such conditions, the NO conversion arrives at 96.82% and the selectivity to N2 is almost 99%. It is of great significance to investigate the influence of reaction conditions in order to provide references for industrial application.

Promotional effect of rare earth-doped manganese oxides supported on activated semi-coke for selective catalytic reduction of NO with NH3

A composite catalyst for the selective catalytic reduction (SCR) of NO_x with NH₃ is investigated, in which the rare earth (RE, including La, Ce, Pr, and Nd) is doped into manganese oxides supported on activated semi-coke (MnO_x/ASC) via hydrothermal method at the molar ratio of Mn:RE = 1:5. It is evidenced that the addition of RE at a rather low molar ratio can enhance the catalytic activity of MnO_x/ASC. The catalyst with a Mn:Ce molar ratio of 10:1 yields an over 90% NO_x removal efficiency in the temperature range of 150-250 °C. An approximate 100% NO conversion and 95% N₂ selectivity are achieved at about 200 °C. The catalysts are characterized by N₂ physisorption, X-ray powder diffraction (XRD), scanning electron microscope (SEM), hydrogen temperature-programmed reduction (H₂-TPR) and X-ray photoelectron spectroscopy (XPS). The results indicated that the Ce additive is conducive to the NO_x adsorption and then accelerates the SCR reaction due to the formation of more chemisorbed oxygen (O_β), which is favored during the oxidation of NH₃ and NO. Moreover, the in situ diffused reflectance infrared Fourier transform spectroscopy (DRIFTS) results confirm that the Ce additive on MnO_x/ASC catalyst could provide more active Brønsted acid sites, which eventually contributes to the SCR reaction. The generation of ad-NH₄⁺ and nitrite species is proved to play the crucial role in the promotional effect of RE addition.