Low Temperature Performance of Selective Catalytic Reduction of NO with NH3 under a Concentrated CO2 Atmosphere

Xiang Gou,Chunfei Wu,Yating Wang,Enyu Wang,Guoyou Xu,Liansheng Liu,Kai Zhang,Meng Si,Jinxiang Wu

doi:10.3390/en81112319

Xiang Gou, Chunfei Wu + Show 7 more

Open Access

https://doi.org/10.3390/en81112319

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Journal: Energies	Publication Date: Oct 30, 2015
Citations: 10	License type: CC BY 4.0

Affiliation: Hebei University of Technology, University of Hull

Abstract

Selective catalytic reduction of NOx with NH3 (NH3-SCR) has been widely investigated to reduce NOx emissions from combustion processes, which cause environmental challenges. However, most of the current work on NOx reduction has focused on using feed gas without CO2 or containing small amounts of CO2. In the future, oxy-fuel combustion will play an important role for power generation, and this process generates high concentrations of CO2 in flue gas. Therefore, studies on the SCR process under concentrated CO2 atmosphere conditions are important for future SCR deployment in oxy-fuel combustion processes. In this work, Mn- and Ce-based catalysts using activated carbon as support were used to investigate the effect of CO2 on NO conversion. A N2 atmosphere was used for comparison. Different process conditions such as temperature, SO2 concentration, H2O content in the feed gas and space velocity were studied. Under Mn-Ce/AC conditions, the results suggested that Mn metal could reduce the inhibition effect of CO2 on the NO conversion, while Ce metal increased the inhibition effect of CO2. High space velocity also resulted in a reduction of CO2 inhibition on the NO conversion, although the overall performance of SCR was greatly reduced at high space velocity. Future investigations to design novel Mn-based catalysts are suggested to enhance the SCR performance under concentrated CO2 atmosphere conditions.

Highlights

NOx emissions are responsible for acid rain and urban smog, and they pose a significant risk to the environment and human health [1]
Simulated gases (NO, NH3 and O2 balanced with N2 or CO2) with a total flow rate of 1200 mL/min were introduced into the reaction system, where 2 g of catalyst was located
We suggest that the formed Mn-based species might reduce the adsorption of NH3 by CO2

Summary

Introduction

NOx emissions are responsible for acid rain and urban smog, and they pose a significant risk to the environment and human health [1]. There is very limited work about the investigation of low-temperature SCR under high concentrations of CO2, simulating the flue gas from oxy-fuel combustion processes. Magnusson et al [25] investigated SCR using a marine based catalyst; they reported that higher space velocity (18,300 h1) resulted in a continuous decrease in catalytic activity, compared with space velocities of 6100 and 12,200 h1; in addition, they reported that at temperatures higher than 300 ̋C, the catalyst showed a stable catalytic reactivity at different SO2 concentrations, but a significant reduction of SCR activity was observed at a temperature of 250 ̋C for gas streams containing 250 and 750 ppm SO2. The performance of SCR catalyst under CO2 atmosphere was compared to an inert N2 atmosphere at various process conditions

Catalyst Preparation

Experimental System

Results and Discussion

Conclusions