Coupling effect of Fe-based catalyst on Nitrogen oxides control in the process of nitrogen reduction and combustion denitration of long flame coal pyrolysis

ABSTRACT

Civil dispersed coal combustion has become an important source of Nitrogen oxides (NOx), which has caused serious pollution to the ecological environment. In order to control NOx emission in the combustion process of civil coal, coal-based solid clean fuel should be used instead of dispersed combustion of coal, so as to achieve the purpose of reducing NOx emission. The pyrolysis and combustion tests of different iron additives loaded coals were performed. The raw and pyrolytic chars were prepared and characterized by X-ray photoelectron spectroscopy (XPS), nitrogen adsorption, scanning electron microscope (SEM) and X-ray diffraction (XRD). The results indicate that iron additives introduced into raw coal in one step have coupling effect on NOx emission control during pyrolysis and combustion. The addition of iron can lead to more Fe₂O₃, Fe₃O₄ and α-Fe in coke and promote coke cracking. Supporting iron catalysts could make coke structure more porous, which increases the contact area of gas. These all make the conversion of N₂ increase from 16.71% to 29.64% during pyrolysis. The existence of iron catalyst can also promote the proportion of pyridinic N (N-6) and quaternary nitrogen (N-Q) relatively increase. At the same time, the existence of iron catalyst is beneficial to catalytic reduction of NOx by C and CO. The emissions of NOx during combustion can be reduced by 34.01%. The iron catalyst introduced in one step has a coupling effect on NOx control in coal pyrolysis-combustion process, which realizes a two-step nitrogen reduction effect in combustion. It provides theoretical basis for ultra-low NOx emission in clean fuel combustion.

KEYWORDS:

• FeCl₃ additive
• pyrolysis
• combustion
• nitrogen oxides
• coupling-effect

Acknowledgments

This work was supported by National Natural Science Foundation of China (21878210), Shanxi “1331” Civil Clean Fuel Engineering Research Center, Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi (2019L0313), Patent Promotion and implementation in Shanxi Province (20200719) and sponsored by Taiyuan Green Coke Energy Co., Ltd. (China).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi [2019L0313]; Patent Promotion and implementation in Shanxi Province [20200719]; National Natural Science Foundation of China [21878210].