Effect of K-decoration on the generation and reduction of N2O onto a biochar surface. (15th May 2022)

• Record Type: Journal Article
• Authors: Feng, Kaixuan; Hu, Yuyan; Cao, Tongcheng
• Is Part Of: Fuel. Volume 316(2022)
• Publication Date: 2022-05-15
• Subjects: Biochar -- Nitrous oxide -- Potassium -- Density function theory -- Heterogeneous reaction; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2022.123148
• Languages: English
• ISSNs: 0016-2361

Abstract

Abstract: Density functional theory calculations, with corrections for London dispersion interactions, have here been used in studying the generation and decomposition of N 2 O through the heterogeneous reduction of NO on a biochar surface. The effect of K-decoration on this specific mechanism has also been investigated. The results show that there are two possible pathways for the generation and decomposition of N 2 O on the pristine char surface, depending on type of reaction site. In the formation stage of N 2 O, the reactions rates of the two pathways are remarkably similar. However, the activation energies of those pathways are different for the decomposition stage of N 2 O (166.75 kJ/mol and 117.51 kJ/mol respectively). Decoration by K does not change these original reaction pathways. However, it decreases the activation energy for the rate-determining step and, thus, increases the total reaction rate. The activation energy is reduced by 13 kJ/mol for the generation of N 2 O and the effect is even larger for the process of N 2 O decomposition. For this latter type of process, the K-induced activation energies for the two pathways are reduced by 97.69 kJ/mol and 48.45 kJ/mol in comparison to pristine char. Moreover, the reaction rates of the different reaction pathways were observed to gradually increase with an increase in temperature. In addition, the difference between the reaction rates for the pathway of the pristine char, and that of the K-decorated char, was found to decrease, which is most probably due to the sublimation of K atoms at higher temperatures. Graphical abstract: Highlights: Study on intermediate product N2 O during NO reducing on the biochar. Two reaction pathways for the N2 O generation and decomposition. Reactions rates are different during N2 O decomposition in two pathways. The K decoration does not change the reaction pathway. The K decoration can improve the reaction rate.