Topic
Selective catalytic reduction
About: Selective catalytic reduction is a research topic. Over the lifetime, 10502 publications have been published within this topic receiving 226291 citations.
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TL;DR: CeO2/Al2O3 catalysts prepared by three methods were investigated for selective reduction of NO with NH3 as discussed by the authors, and it was found that the catalyst prepared by the single step sol-gel method had the best SCR activity and SO2 resistance performance.
108 citations
TL;DR: In this paper, the selective catalytic reduction of NOx (NO + NO2) at low temperature with ammonia has been investigated with natural manganese ore, pure manganes dioxide, and manganous dioxide supported alumina.
Abstract: The selective catalytic reduction of NOx (NO + NO2) at low temperature with ammonia has been investigated with natural manganese ore, pure manganese dioxide, and manganese dioxide supported alumina. The catalysts showed high activities for NOx reduction with NH3 in the presence of O2 at temperatures below 250 °C. The decrease of SCR activity without oxygen in the gas phase differed among the three catalysts in accord with their differing amounts of lattice oxygen. The SCR activity of the catalysts, in that case, decreased in the order MnO2 > NMO > MnO2/γ-Al2O3. Small amounts of SO2 deactivated the catalysts in the low-temperature range. An XRD analysis of the sulfated catalysts with differing temperature provides evidence that the formation of ammonium sulfates is the main poisoning route. These results could restrict the practical application of these catalysts to sulfur-free conditions.
107 citations
TL;DR: In this article, it is suggested that the reduction of ad-NO x species and NO 2 by propene over the 1.2.2% Ag/γ-Al 2 O 3 catalyst was associated with a decrease of the activity for the oxidation of NO to ad- NO x species ( x ǫ > 1) promoted by the silver phase.
Abstract: A 1.2 wt.% Ag/γ-Al 2 O 3 catalyst for the selective catalytic reduction of NO with propene (C 3 H 6 -SCR) was rapidly and permanently deactivated following the addition of 100 ppm of SO 2 to the gas stream. DRIFTS studies performed on the deactivated silver–alumina material showed the formation of two different types of surface sulphate species. One of these surface species was a surface aluminium sulphate whereas the other corresponded to a sulphate associated with the silver phase. Treatment at higher temperatures in the deNO x feed did not regenerate the catalytic activity fully whereas reduction with H 2 was able to do so by removing only the sulphate species associated with the silver phase. When NO 2 was used as reactant, there was no need for a promoter for either the alumina or the sulphated alumina, both of those giving high conversions of the NO 2 to N 2 over a wide temperature window. The decrease in the SCR activity observed over the Ag/γ-Al 2 O 3 upon sulphation is thought to be associated with a decrease of the activity for the oxidation of NO to ad-NO x species ( x > 1) promoted by the silver. It is suggested that the reduction of ad-NO x species and NO 2 by propene over the 1.2 wt.% Ag/γ-Al 2 O 3 catalyst (plain or sulphated) mostly occurred on the alumina (clean or sulphated).
107 citations
TL;DR: In this paper, the effect of ammonia supply on the selective catalytic reduction of NOX over zeolite H-ZSM-5 was investigated using step response experiments between 200 and 500 degrees C.
107 citations
TL;DR: In this paper, the authors show that a catalyst is necessary for the formation of N2 and emphasize the importance of O2 in maintaining an adequate supply of NO2, particularly at temperatures above 800 K where equilibrium favors NO.
107 citations