Influence factors and mechanism of selective catalytic reduction of NO in the flue gas over activated coke

ABSTRACT

The aim of this study was to study the influence factors of selective catalytic reduction (SCR) of NO with NH₃ in flue gas and to clarify the mechanism of SCR over activated coke (AC). An AC in various simulated flue gases for reduction of NO was examined in a fixed-bed reactor. X-ray photoelectron spectroscopy (XPS) was used to performhigh-resolution scanning of surface N element. The results indicate that the presence of O₂ in flue gas facilitates the NO reduction in SCR. Higher polarity of H₂O molecule may inhibit NH₃ or NO adsorption on the surface of ACs, so that NO reduction has been restrained. A lowest NO conversion was tested at 250°C in the temperature range of 100–350°C, meaning that may presence of different SCR mechanism at low or high temperature. Adsorption of NH₃ below 250°C is dominated by physical adsorption and adsorption of NH₃ higher than 250°C is dominatedby the chemical reaction between NH₃ and AC base on the determination of XPS and adsorption capacities of NH₃. There was a good correlation between adsorption capacity of NH₃ and NO conversion, which indicated that NH₃ adsorption is a key step in SCR regardless of whether NH₃ was physically or chemically adsorbed on the AC.

KEYWORDS:

• Activated coke
• selective catalytic reduction
• nitric oxide
• flue gas

Additional information

Funding

This project is supported by National Key Research and Development Program of China [Grant No. 2016YFC0204100].

Notes on contributors

Xie Wei

Xie Wei received his B.S degree in Chemical Engineering from the Anhui University of Science & Technology, Huainan, China and his M.S. in Chemical Technology from China University of Mining & Technology, Beijing, China. He is doctor candidate in the field of carbon material and flue gas cleaning.

Wu Tao

Wu Tao obtained B.S. degree in Chemical Engineering from East China University Technology, NanChang, China and M. S. in Chemical Technology from China Coal Research Institute, Beijing, China. She has worked in the areas of coal-based carbon material.

Qu Si Jian

Qu Si Jian Holds a Ph. D. from China University of Mining & Technology, Beijing, China and was a researcher in China Coal Research Institute (CCRI) for over 25 years and he is chief engineering of CCRI now.

Li Lan Ting

Li Lan Ting received his a Ph. D. from China University of Mining & Technology, Beijing, China and work in Beijing Key Laboratory of Coal Based Carbon Materials. He developed preparation technology of coal based activated carbon.

Wang Peng

Wang Peng obtained M.S. degree in Chemical Technology from Beijing University of Chemical Technology, Beijing, China. He is currently with applied technology of activated carbon.