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: In this paper, a series of catalysts of manganese oxide, cerium oxide and iron-manganese oxide supported on USY (ultra-stable Y zeolite) were studied for the low-temperature selective catalytic reduction (SCR) of NO with ammonia in the presence of excess oxygen.
Abstract: A series of catalysts of manganese oxide, manganese–cerium and iron–manganese oxide supported on USY (ultra-stable Y zeolite) were studied for the low-temperature selective catalytic reduction (SCR) of NO with ammonia in the presence of excess oxygen. It was found that MnOx/USY have high activity and high selectivity to N2 in the temperature range 80-180 °C. The addition of iron and cerium oxide increased NO conversion significantly although the single-component Fe/USY and Ce/USY catalysts had low activities. Among the catalysts studied in this work, the 14% Ce-6% Mn/USY showed the highest activity. The results showed that this catalyst yielded nearly 100% NO conversion at 180 °C at a space velocity of 30 000 cm3 g-1 h-1. The only product is N2 (with no N2O) below 150 °C. The effects of the concentration of oxygen, NO and NH3 were studied and the steady-state kinetics were also investigated. The reaction order is 1 with respect to NO and zero with respect to NH3 on the 14% Ce-6% Mn/USY catalyst at 150 °C.
99 citations
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TL;DR: In this paper, the performance of the CeO2-CuO catalyst was investigated for selective catalytic reduction of NO with NH3, and it was found that the state of Cu species had a great impact on the SCR performance.
99 citations
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TL;DR: In this paper, a review of chemical poisoning on V2O5-based catalysts, environmental-benign catalysts and low temperature catalysts is presented, where several poisons including alkali/alkaline earth metals, SO2 and heavy metals etc.
Abstract: Selective catalytic reduction (SCR) of NO
x
with NH3 is an effective technique to remove NO
x
from stationary sources, such as coal-fired power plant and industrial boilers. Some of elements in the fly ash deactivate the catalyst due to strong chemisorptions on the active sites. The poisons may act by simply blocking active sites or alter the adsorption behaviors of reactants and products by an electronic interaction. This review is mainly focused on the chemical poisoning on V2O5-based catalysts, environmental-benign catalysts and low temperature catalysts. Several common poisons including alkali/alkaline earth metals, SO2 and heavy metals etc. are referred and their poisoning mechanisms on catalysts are discussed. The regeneration methods of poisoned catalysts and the development of poison-resistance catalysts are also compared and analyzed. Finally, future research directions in developing poisoning resistance catalysts and facile efficient regeneration methods for SCR catalysts are proposed.
99 citations
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TL;DR: In this paper, a 10-wt% Ce/TiO 2 catalysts were prepared via wet impregnation at different calcination temperatures and used for selective catalytic oxidation (SCO) of NH 3 to N 2.
Abstract: Herein, 10 wt% Ce/TiO 2 catalysts were prepared via wet impregnation at different calcination temperatures and used for selective catalytic oxidation (SCO) of NH 3 to N 2 The 10 wt% Ce/TiO 2 catalyst calcined at 400 °C showed the highest NH 3 conversion (∼96%) and N 2 (∼93%) yield (at 350 °C) As determined by BET and XRD studies, the ceria oxides existed in either highly dispersed or amorphous phases after preparation at low calcination temperatures ( 2 catalysts were investigated using TPR, TPD, XPS, and in situ FT-IR spectroscopy The activity for the SCO of NH 3 to N 2 of the 10 wt% Ce/TiO 2 catalysts prepared at different calcination temperatures depend on the oxidation states of the Ce species and behavior of oxygen within the catalyst The SCO of NH 3 to N 2 over Ce/TiO 2 calcined at 400 °C follows an internal selective catalytic reduction mechanism
98 citations
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TL;DR: In this paper, a review summarizes major advances in Cu-SSZ-13 applied to the NH3-SCR reaction, including the state of copper species, standard and fast SCR reaction mechanism, hydrothermal deactivation mechanism, poisoning resistance and synthetic methodology.
Abstract: Zeolites, as efficient and stable catalysts, are widely used in the environmental catalysis field. Typically, Cu-SSZ-13 with small-pore structure shows excellent catalytic activity for selective catalytic reduction of NO x with ammonia (NH3-SCR) as well as high hydrothermal stability. This review summarizes major advances in Cu-SSZ-13 applied to the NH3-SCR reaction, including the state of copper species, standard and fast SCR reaction mechanism, hydrothermal deactivation mechanism, poisoning resistance and synthetic methodology. The review gives a valuable summary of new insights into the matching between SCR catalyst design principles and the characteristics of Cu2+-exchanged zeolitic catalysts, highlighting the significant opportunity presented by zeolite-based catalysts. Principles for designing zeolites with excellent NH3-SCR performance and hydrothermal stability are proposed. On the basis of these principles, more hydrothermally stable Cu-AEI and Cu-LTA zeolites are elaborated as well as other alternative zeolites applied to NH3-SCR. Finally, we call attention to the challenges facing Cu-based small-pore zeolites that still need to be addressed.
98 citations