Experimental study of the influence of sodium salts as additive to NO x OUT process

Liang, Xin; Zhong, Zhaoping; Jin, Baosheng; Chen, Xiaolin; Li, Weiling; Wei, Hongge; Guo, Huajun

doi:10.1007/s11814-010-0228-1

Cited by 4 publications

(3 citation statements)

References 20 publications

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“…The results are in good agreement with observations reported in the literature. A promoting effect of various Na/K additives (chlorides, carbonates, and hydroxides) on NO reduction has been demonstrated in SNCR experiments with both NH 3 − and urea − as additives. The presence of alkali salts acts to widen the window for the process to lower temperatures, typically by 50–100 °C, while the performance at temperatures at and above the optimum is only slightly affected.…”

Section: Resultsmentioning

confidence: 93%

“…The SNCR process is known to be strongly temperature dependent, with a narrow temperature window of effective NO reduction, typically located around 850–1100 °C. The process has been studied extensively in the past and is considered a mature technology for NO x reduction in stationary sources. , Previous studies have shown that important process parameters for SNCR include temperature, residence time, injection rate of the chemical reducing agent, mixing of reagent with the flue gas, , oxygen concentration, , and presence of combustibles. − Also the impact of alkali metals − and SO 2 has been investigated. − …”

Section: Introductionmentioning

confidence: 99%

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Selective Noncatalytic Reduction of NO_x Using Ammonium Sulfate

Krum

Jensen

et al. 2021

Energy Fuels

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Ammonium sulfate (AS) is of interest as an additive in stationary combustion plants for the simultaneous control of NO x (through selective noncatalytic reduction, SNCR) and deposition and corrosion (through sulfation of alkali chlorides). The SNCR performance of ammonium sulfate was evaluated through experiments in a laboratory-scale flow reactor. Experiments with 5 and 10 wt % aqueous ammonium sulfate solutions, corresponding to AS/NO ratios above 1, yielded NO reductions up to 95% in a temperature interval of 1025–1075 °C. The results indicated that sulfur from ammonium sulfate is mainly released as SO3, even though SO2 is detected in increasing concentrations at temperatures above 1000 °C. Addition of KCl to the SNCR process was shown to promote the reaction at lower temperatures, extending the temperature window for reduction by 50 °C. Furthermore, ammonium sulfate facilitated a high degree of KCl sulfation at or below 1000 °C, demonstrating the potential of using ammonium sulfate to simultaneously reduce NO x and corrosion in full-scale combustion plants. The experiments were analyzed in terms of a detailed kinetic model. The SNCR experiments using ammonium sulfate were described satisfactorily by the model, although the NO reduction at the optimum was slightly underestimated. Also, the sulfation of KCl was captured well, but the promoting effect of KCl on SNCR with ammonium sulfate was greatly underestimated. Possible reasons for this discrepancy were discussed.

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Section: Resultsmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Selective Noncatalytic Reduction of NO_x Using Ammonium Sulfate

Krum

Jensen

et al. 2021

Energy Fuels

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“…Health and environmental concerns prompted by emission of nitrogen oxides (NO x ) from thermal operations triggered the development of several abatement technologies . In particular, the selective catalytic reduction − and selective noncatalytic reduction (SNCR) − have emerged as effective approaches to reduce NO x emission from thermal processes. The catalytic conversion of nitrogen monoxide (NO) into molecular nitrogen has led to a remarkable drop in emissions of NO x from mobile and stationary sources alike.…”

Section: Introductionmentioning

confidence: 99%

Conversion of NO into N₂ over γ-Mo₂N

et al. 2016

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Cubic molybdenum nitride (γ-Mo2N) exhibits Pt-like catalytic behavior in many chemical applications, most notably as a potent catalyst for conversion of harmful NO x gases into N2. Guided by experimental profiles from adsorption of 15NO on γ-Mo2 14N, we map out plausible mechanisms for the formation of the three isotopologues of dinitrogen (14N2, 15N2, and 14N15N) in addition to 14N15NO. By deploying cluster models for the γ-Mo2N(100) and γ-Mo2N(111) surfaces, we demonstrate facile dissociative adsorption of NO on γ-Mo2N surfaces. Surfaces of γ-Mo2N clearly activate adsorbed 15NO molecules, as evidenced by high binding energies and the noticeable elongation of the N–O bonds. 15NO molecule dissociates through modest reaction barriers of 24.1 and 28.1 kcal/mol over γ-Mo2N(100) and γ-Mo2N(111) clusters; respectively. Dissociative adsorption of a second 15NO molecule produces the experimentally observed Mo2O x N y phase. Over the 100 surface, subsequent uptake of 15NO continues to occur until the dissociated O and N atoms occupy all 4-fold hollow and top sites. We find that, the direct desorption of 15N2 from the Mo2O x N y -like phases phase requires a sizable energy barrier to precede. Considering a preoxygen surface covered cluster reduces this energy barrier only marginally. Desorption of 15N2 molecules takes place upon combination of two adjacent N atoms from top sites via a low-energy multistep Langmuir–Hinshelwood mechanism. Dissociative adsorption of gaseous 15NO molecules at surface Mo–N bonds weakens the Mo–N bonds and leads to formation of 14N15N molecules (where 14N denotes a nitrogen atom originated from surfaces of γ-Mo2N crystals). Liberation of 14N2 molecules occurs via surface diffusion of two surface N atoms on the (111) N-terminated surface. Formation of 14N15NO proceeds via direct abstraction of a surface 14N atom by a gaseous 15NO adduct.

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