Reaction Characteristics of NOx and N2O in Selective Non-Catalytic Reduction Using Various Reducing Agents and Additives

Poong-Mo Park,Jong-In Dong,Young-Kwon Park

doi:10.3390/atmos12091175

Poong-Mo Park, Jong-In Dong + Show 1 more

Open Access

https://doi.org/10.3390/atmos12091175

Copy DOI

Abstract

Artificial nitrogen oxide (NOx) emissions due to the combustion of fossil fuels constitute more than 75% of the total NOx emissions. Given the continuous reinforcement of NOx emission standards worldwide, the development of environmentally and economically friendly NOx reduction techniques has attracted much attention. This study investigates the selective non-catalytic reduction (SNCR) of NOx by methane, ammonia, and urea in the presence of sodium carbonate and methanol and the concomitant generation of N2O. In addition, the SNCR mechanism is explored using a chemical modeling software (CHEMKIN III). Under optimal conditions, NOx reduction efficiencies of 80–85%, 66–68%, and 32–34% are achieved for ammonia, urea, and methane, respectively. The N2O levels generated using methane (18–21 ppm) were significantly lower than those generated using urea and ammonia. Addition of sodium carbonate and methanol increased the NOx reduction efficiency by methane to ≥40% and 60%, respectively. For the former, the N2O level and reaction temperature further decreased to 2–3 ppm and 850–900 °C, respectively. The experimental results were well consistent with simulations, and the minor discrepancies were attributed to microscopic variables. Thus, our work provides essential guidelines for selecting the best available NOx control technology.

Highlights

Nitrogen oxides (NOx ), along with sulfur oxides and dust, are representative air pollutants predominantly produced through the combustion of fossil fuels and are precursors of particulate matter [1,2]
Artificial NOx emissions due to fossil fuel combustion represent more than 75% of the total NOx emissions [3], which highlights the need for effective NOx abatement methods
This study investigates the reduction of NO by methane, ammonia, mechanism is probed using a chemical modeling software (CHEMKIN III). x and urea and the concomitant generation of N2 O

Summary

Introduction

Nitrogen oxides (NOx ), along with sulfur oxides and dust, are representative air pollutants predominantly produced through the combustion of fossil fuels and are precursors of particulate matter [1,2]. Among the NOx reduction technologies applied to various industrial processes involving combustion, selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR) are noteworthy post-treatment prevention methods [4,5]. Given that SNCR has been used as the best available control technology and best available technique in numerous countries [6,7,8], many researchers have attempted to improve its NOx reduction efficiency by altering the reaction conditions, e.g., through the introduction of auxiliary agents and additives [9,10,11]. Amines and cyanides are predominantly used as the reducing agents; ammonia and urea have been used in general industrial processes [12].

Methods

Results

Conclusion