Effects of ammonia-coal co-pyrolysis on heterogeneous reduction of NO: Quantum chemical calculations and pyrolytic reduction experiments

Chuanjin Zhao, Hai Zhang, Kunmin Wu, Saibei Luo and Weidong Fan

Energy, 2025, vol. 321, issue C

Abstract: Ammonia-coal co-combustion is a promising technology for reducing carbon dioxide emissions. However, the mechanism by which nitrogen-containing functional groups in the post-flame zone influence carbon during the co-combustion process is unclear. In this study, it is assumed that -NH2 groups enhance nitrogen monoxide reduction by activating the char surface. Quantum chemical calculations, pyrolysis reduction experiments and X-ray Photoelectron Spectroscopy (XPS) experiments were combined to investigate -NH2 modified char's reactivity. Quantum calculations show that the -NH2 group activates the char surface, effectively enhancing the NO reduction on the char, with advantages in both thermodynamics and kinetics. Additionally, the calculations reveal that both -H and -NH (further pyrolysis products of -NH2) can also lower the energy barrier for NO reduction on the char. The pyrolysis reduction experiment results show that increasing the co-pyrolysis temperature and ammonia blending ratio enhances the char's ability to reduce NO. Further XPS experiments reveal that the NO reduction rate exceeds the rate of decrease of char-NH2, and this characteristic becomes more pronounced with increasing ammonia concentration during the co-pyrolysis stage. This confirms that the surface heterogeneous reduction of NO on char-NH2 is an important pathway in the absence of -NH2 involvement in the reaction.

Keywords: DFT; Ammonia; Pyrolysis; NO heterogeneous reduction; Coal char (search for similar items in EconPapers)
Date: 2025
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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:321:y:2025:i:c:s0360544225011387

DOI: 10.1016/j.energy.2025.135496

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