The Enhanced Performance of N-Modified Activated Carbon Promoted with Ce in Selective Catalytic Reduction of NOx with NH3

Marwa Saad,Bogdan Samojeden,Monika Motak,Anna Białas,Agnieszka Szymaszek

doi:10.3390/catal10121423

Abstract

The goal of the study was to modify activated carbon (AC) with nitrogen groups and ceria and to test the obtained materials in low temperature selective catalytic reduction of nitrogen oxides. For that purpose, the starting AC was oxidized with HNO3 of various concentrations, modified with urea and doped with 0.5 wt.% of Ce. It was observed that the increased concentration of acid influenced the catalytic activity, since textural and surface chemistry of activated carbon was changed. The most active sample was that modified with 14 M HNO3 and it reached 96% of NO conversion at 300 °C. Additionally, the addition of Ce improved the catalytic performance of modified AC, and NO was reduced according to oxidation–reduction mechanism, characteristic for supported metal oxides. Nevertheless, the samples promoted with Ce emitted significantly higher amount of CO2 comparing to the non-promoted ones.

Highlights

Nitrogen oxides (NOx ) emitted from the stationary sources are one of the major pollutants introduced into the atmosphere [1,2,3]
The authors concluded that oxidation with HNO3 followed by treatment with urea or ammonia was a key factor in the improved catalytic performance
Samojeden et al [4], who investigated the influence of the modification of activated carbon on its performance in NH3 -SCR, postulated that the matter of oxidation is complicated by the fact that both the initial structure of carbonaceous materials and the type of oxidative pretreatment play an important role and only semi-quantitative prediction on the type and number of groups may be generally given

Summary

Introduction

Nitrogen oxides (NOx ) emitted from the stationary sources are one of the major pollutants introduced into the atmosphere [1,2,3]. The most significant is a narrow temperature window that forces to install the catalyst at high dust position, before electrostatic precipitator and desulfurization installation. In such a position, the catalytic system is exposed to high concentration of SO2 and fly ash that poison the active sites. The catalytic system is exposed to high concentration of SO2 and fly ash that poison the active sites These contaminations can form deposits that plug the catalysts channels [2,7,8]

Objectives

Methods

Results

Conclusion