Ammonium Ion Enhanced V2O5-WO3/TiO2 Catalysts for Selective Catalytic Reduction with Ammonia.

Min Seong Lee,Duck Hyun Lee,Jin-Woo Park,Bora Jeong,Taehyo Kim,Gibum Kwon,Sun-I Kim,Jung Woo Lee

doi:10.3390/nano11102677

Abstract

Selective catalytic reduction (SCR) is the most efficient NOX removal technology, and the vanadium-based catalyst is mainly used in SCR technology. The vanadium-based catalyst showed higher NOX removal performance in the high-temperature range but catalytic efficiency decreased at lower temperatures, following exposure to SOX because of the generation of ammonium sulfate on the catalyst surface. To overcome these limitations, we coated an NH4+ layer on a vanadium-based catalyst. After silane coating the V2O5-WO3/TiO2 catalyst by vapor evaporation, the silanized catalyst was heat treated under NH3 gas. By decomposing the silane on the surface, an NH4+ layer was formed on the catalyst surface through a substitution reaction. We observed high NOX removal efficiency over a wide temperature range by coating an NH4+ layer on a vanadium-based catalyst. This layer shows high proton conductivity, which leads to the reduction of vanadium oxides and tungsten oxide; additionally, the NOX removal performance was improved over a wide temperature range. These findings provide a new mothed to develop SCR catalyst with high efficiency at a wide temperature range.

Highlights

Most energy is generated through the combustion of fossil fuels, which causes air pollution by emitting toxic pollutants, such as NOX, particulate matter, SOX, and CO [1,2].Nitrogen oxides (NO, NO2, and N2 O) are the most representative air pollutants because they are major causes of acid rain, photochemical smog, ozone depletion, and global warming [3,4,5]
The NH4 + -coated V2 O5 -WO3 /TiO2 catalyst was prepared in three steps: first, V2 O5 WO3 /TiO2 was synthesized by the impregnation method, and the catalyst underwent vapor phase silane treatment at 180 ◦ C for 1h
After silane coating by vapor deposition, the catalysts were heat treated at 500 ◦ C under 300 ppm NH3 gas with N2 gas for 2 h

Summary

Introduction

Most energy is generated through the combustion of fossil fuels, which causes air pollution by emitting toxic pollutants, such as NOX , particulate matter, SOX , and CO [1,2].Nitrogen oxides (NO, NO2 , and N2 O) are the most representative air pollutants because they are major causes of acid rain, photochemical smog, ozone depletion, and global warming [3,4,5]. NOX is emitted by automobiles, power stations, industrial heaters, and non-road vehicles. To reduce this form of pollution, NOX removal technologies must be developed. Many technologies have been developed to control NOX emissions, such as selective catalytic reduction (SCR), non-selective catalytic reduction (NSCR), and selective non-catalytic reduction (SNCR). Selective catalytic reduction (SCR), the most efficient NOX removal technology, selectively converts NOX in fuel gas into N2 and H2 O. Compared with other technologies, such as non-selective catalytic reduction (NSCR) and selective noncatalytic reduction (SNCR), SCR shows a high NOX removal efficiency and no secondary pollutant emission and can be operated in the temperature range of 100–300 ◦ C [4]

Methods

Results

Conclusion