Effects of Inherent Metals on NO Reduction by Coal Char

Zhang, Juwei; Sun, Shaozeng; Zhao, Yijun; Hu, Xidong; Xu, Guangwen; Qin, Yukun

doi:10.1021/ef201323j

Cited by 34 publications

(10 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The pyrolysis and gasification, combustion efficiency, and pollutant emissions of Zhundong coal will be affected as a result of the higher alkali metal content in the coal . The previous research studies by the authors and their team − indicated that the heterogeneous reaction of NO is an important component of the NO reduction. The physical and chemical characteristics of coal, such as the specific surface area of char and metal oxide contents, are important factors affecting the reduction of NO.…”

Section: Introductionmentioning

confidence: 99%

“…The physical and chemical characteristics of coal, such as the specific surface area of char and metal oxide contents, are important factors affecting the reduction of NO. Furthermore, sodium in coal improved the activity of in situ coal char, promoting the heterogeneous reduction of NO by coal char in the boiler, , thereby increasing the reduction rate of nitrogen oxides. However, the micromechanism of the heterogeneous reduction of NO on the sodium-doped char surface is not clear.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Mechanism of the Heterogeneous Reduction of NO on a Sodium-Doped Char Surface: A First-Principles Study

et al. 2021

View full text Add to dashboard Cite

Sodium in high-alkali coal facilitates the heterogeneous reduction of nitrogen oxides on char surfaces. However, the reaction mechanism is unclear. In this paper, the effect of sodium on the reaction path of the char heterogeneous reduction of NO was analyzed based on the first-principles study using an armchair char model and a zigzag char model separately. Four reaction paths were obtained, and the most likely reaction path was found by comparison. The highest energy barriers of the reduction reactions were reduced to some extent by doping with the sodium atom. The doped sodium atom had a significant effect on the heterogeneous reduction reactions on the surface of the armchair char and had little effect on the surface of the zigzag char. However, a comprehensive analysis showed that the reactivity of the zigzag model is better than that of the armchair model. From the thermodynamic analysis, the addition of the sodium atom could change the reaction from nonspontaneous to spontaneous. After the completion of the reaction, the oxygen atom would be immobilized on the char structure surface, which will have an effect on the subsequent reaction. This study revealed the effect of the sodium atom on the reaction mechanism of the char heterogeneous reduction of NO and helped perfect the mechanism of the char heterogeneous reduction of NO.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mechanism of the Heterogeneous Reduction of NO on a Sodium-Doped Char Surface: A First-Principles Study

et al. 2021

View full text Add to dashboard Cite

show abstract

“…There are abundant coal resources in the Zhundong area of Xinjiang, but the content of sodium oxide in Zhundong coal is more than 2%, which belongs to typical high-sodium coal . Sodium in coal not only promoted the pyrolysis and gasification process of coal , but also improved the activity of in situ coal char, thus promoting the heterogeneous reduction of NO by char in the reburning zone of a boiler, and decreased the nitrogen oxide emissions. The effect of sodium additives on the release of fuel nitrogen by using TG/EGA (thermogravimetry/evolved gas analysis) equipment has been studied by Liu et al, and it was found that the presence of sodium catalyzed the reduction of NO by char.…”

Section: Introductionmentioning

confidence: 99%

Density Functional Theory Study on the Effect of Sodium on the Adsorption of NO on a Char Surface

et al. 2020

View full text Add to dashboard Cite

In order to clarify the effect of sodium on the heterogeneous adsorption of NO on a char surface, several reasonably simplified saturated and unsaturated char models were selected as research objects, and Na atoms were decorated on the char models. Each char model and NO adsorption product were optimized by using density functional theory at the GGA-PBE (generalized gradient approximation-Perdew−Burke−Ernzerhof) level to obtain the adsorption energy of NO on different models. The results indicate that the addition of Na atoms catalyzes the adsorption of NO molecules by an saturated char structure, the adsorption form is changed from physisorption to chemisorption, and the adsorption energy is increased from −15.6 to −98.2 kJ/ mol. The adsorption energy of NO molecules with an unsaturated armchair-type char structure containing edge active sites is affected by sodium atoms, increasing from −211.7 to −303.6 kJ/mol, while the adsorption capacity of the zigzag-type char structure for NO molecules is hardly affected by Na atoms. This study provides a theoretical basis for the development of clean utilization technology of high-alkali coal.

show abstract

“…Compared with traditional NH 3 –SCR, carbon/char-SCR owns the advantages of low cost, having little problem with duct deterioration and reductant slip . In general, noble metal containing catalyst has a high activity in NO x -SCR, but the high price of noble metal has driven researchers to develop low-cost transition metal catalysts, such as carbon supported Fe, Co, Ni and Cu. , Active carbon supported Cr and Cu catalysts, , and char supported Fe, Cu and Co catalysts all showed activity in NO x -SCR, − in which carbon material functioned as the support and reducing agent. , Note that in some reports, carbon doped/coated catalysts were synthesized, while carbon was only used as the catalyst support and NH 3 as the reducing agent. , Since electroplating sludge contains various metal species and organic matters, its pyrolysis can generate metal/metal oxide/carbon mixture, which would be a potential substitution for metal catalyst in NO x -SCR.…”

Section: Introductionmentioning

confidence: 99%

Efficient Selective Catalytic Reduction of NO by Novel Carbon-doped Metal Catalysts Made from Electroplating Sludge

Zhang

et al. 2014

Environ. Sci. Technol.

View full text Add to dashboard Cite

Electroplating sludges, once regarded as industrial wastes, are precious resources of various transition metals. This research has thus investigated the recycling of an electroplating sludge as a novel carbon-doped metal (Fe, Ni, Mg, Cu, and Zn) catalyst, which was different from a traditional carbon-supported metal catalyst, for effective NO selective catalytic reduction (SCR). This catalyst removed >99.7% NO at a temperature as low as 300°C. It also removed NO steadily (>99%) with a maximum specific accumulative reduced amount (MSARA) of 3.4 mmol/g. Gas species analyses showed that NO removal was accompanied by evolving N 2 and CO 2 . Moreover, in a wide temperature window, the sludge catalyst showed a higher CO 2 selectivity (>99%) than an activated carbon-supported metal catalyst. Structure characterizations revealed that carbon-doped metal was transformed to metal oxide in the sludge catalyst after the catalytic test, with most carbon (2.33 wt %) being consumed. These observations suggest that NO removal over the sludge catalyst is a typical SCR where metals/metal oxides act as the catalytic center and carbon as the reducing reagent. Therefore, our report probably provides an opportunity for high value-added utilizations of heavy-metal wastes in mitigating atmospheric pollutions.

show abstract

Effects of Inherent Metals on NO Reduction by Coal Char

Cited by 34 publications

References 34 publications

Mechanism of the Heterogeneous Reduction of NO on a Sodium-Doped Char Surface: A First-Principles Study

Mechanism of the Heterogeneous Reduction of NO on a Sodium-Doped Char Surface: A First-Principles Study

Density Functional Theory Study on the Effect of Sodium on the Adsorption of NO on a Char Surface

Efficient Selective Catalytic Reduction of NO by Novel Carbon-doped Metal Catalysts Made from Electroplating Sludge

Contact Info

Product

Resources

About