Visualization of SO₂ induced low-temperature SCR catalyst deactivation and regeneration

Session

PSA.8 - Microscopy in industrial applications

Authors

Prof. Hangsheng Yang (1)

Affiliations

1. Zhejiang University

Keywords

In situ ETEM, Low temperature, selective catalytic reduction, SO₂ resistance, steric hindrance

Abstract text

Fossil fuels are and will still be the dominant source of energy in the world. But fossil fuels combustion inevitably emits nitrogen oxides (NO_X). NO_X are one series of the major air pollutants which cause a series of environmental issues (such as smog, acid rain, and ozone depletion) and are harmful for human health. In order to control NO_X emission, the application of post-combustion technology is essential, especially selective catalytic reduction is widely applied in power plants using V₂O₅-WO₃-TiO₂ as catalysts and NH₃ as reductant. To remove NO_X from low-temperature flue gases (in steel, cement, glass, and other important industries), however, remains challenging since the catalysts are severely deactivated by trace SO₂ [1].

Here, by using in-situ ETEM, we successfully observed the interaction between SO₂ and CeO₂ nanorod catalyst in atomic scale and found a dynamic equilibrium between sulfate deposition and decomposition (Fig. 1), which provided a new approach to solve the catalyst deactivation by establishing this dynamic equilibrium at temperature as low as 250 ℃. In the meantime we also studied the steric hindrance effects of the surface ammonia (bi)sulfate network by DFT, and finally developed a MnO_X/CeO₂ catalyst which showed almost no activity loss for 1000 hours test at 250 ℃ in the presence of 200 ppm SO₂ [2].  

Figure 1. Schematic diagram of the proposed mechanism based on in situ ETEM.

 

References

[1] Li B., Ren Z., Ma Z., Huang X., Liu F., Zhang X., Yang H., Catal. Sci. Technol., 6 (2016) 1719-1725.

[2] Ma Z., Sheng L., Wang X., Yuan W., Chen S., Xue W., Han G., Zhang Z., Yang H., Lu Y., Wang Y. Adv. Mater., 31 (2019) 1903719.