Showing papers on "Selective catalytic reduction published in 2020"
TL;DR: In this article, the influence of Fe doped over activated carbon (AC) supported Mn-Ce oxide catalysts was investigated for low-temperature selective catalytic reduction (SCR) of NO with NH3.
159 citations
TL;DR: Different available post-combustion methods of NOx removal, including selective catalytic reduction (using different types of reducing reagents, including ammonia, hydrogen, hydrocarbons, and carbon monoxide), selective noncatalytic reduction, wet scrubbing, adsorption, electron beam, nonthermal plasma, and electrochemical reduction ofNOx, are discussed.
151 citations
TL;DR: The selective catalytic reduction (SCR) technique that converts NOx from the outlet of industrial boilers at low temperature (<200 °C) requires catalysts that possess both the oxidization property and the catalytic property as mentioned in this paper.
Abstract: The selective catalytic reduction (SCR) technique that converts NOx from the outlet of industrial boilers at low temperature (<200 °C) requires catalysts that possess both the oxidization property ...
138 citations
TL;DR: In this paper, a series of Cu-modified Mn3O4 spinels were synthesized, and the roles of the Cu dopant were investigated, and it was shown that doping with the low-valence dopant of Cu can significantly improve low-temperature selective catalytic reduction (SCR) activity and SO2 tolerance.
100 citations
TL;DR: In Fe-V-Ti catalysts, the charge interaction between Fe2O3 and FeVO4 as well as the electronic inductive effect between Fe and V species resulted in the improvement of SCR activity and N2 selectivity at high temperatures.
94 citations
TL;DR: In this article, the authors reviewed recent advances in the design strategies of supported metal catalysts for enhancing the activity of CO2 conversion and its selectivity to CO. This short review may provide insights into future reverse water gas shift (RWGS) catalyst designs and optimization.
Abstract: The catalytic conversion of CO2 to CO via a reverse water gas shift (RWGS) reaction followed by well-established synthesis gas conversion technologies may provide a potential approach to convert CO2 to valuable chemicals and fuels. However, this reaction is mildly endothermic and competed by a strongly exothermic CO2 methanation reaction at low temperatures. Therefore, the improvement in the low-temperature activities and selectivity of the RWGS reaction is a key challenge for catalyst designs. We reviewed recent advances in the design strategies of supported metal catalysts for enhancing the activity of CO2 conversion and its selectivity to CO. These strategies include varying support, tuning metal–support interactions, adding reducible transition metal oxide promoters, forming bimetallic alloys, adding alkali metals, and enveloping metal particles. These advances suggest that enhancing CO2 adsorption and facilitating CO desorption are key factors to enhance CO2 conversion and CO selectivity. This short review may provide insights into future RWGS catalyst designs and optimization.
87 citations
TL;DR: A novel H-SAPO-34-supported ceria-promoted copper-based catalyst that demonstrated exceptional resistance against alkali, alkaline earth, and heavy metal poisoning during SCR of NOx is reported here.
Abstract: Selective catalytic reduction (SCR) of NOx using NH3 in the presence of alkaline and heavy metals is still an issue in the application of a stationary source. Reported here is the rational design o...
85 citations
TL;DR: The NH3-mediated selective catalytic reduction (NH3-SCR) of NOx over Cu-ion-exchanged chabazite (Cu-CHA) catalysts is the basis of the technology for abatement of diesel vehicles.
Abstract: The NH3-mediated selective catalytic reduction (NH3-SCR) of NOx over Cu-ion-exchanged chabazite (Cu-CHA) catalysts is the basis of the technology for abatement of NOx from diesel vehicles. A crucia...
81 citations
TL;DR: Light is shed on deactivation mechanism of heavy metals and SO2 over CeO2-WO3/TiO2 catalysts and provides innovative pathway for inventing high-performance SCR catalysts, which have great resistance to heavy metal andSO2 simultaneously.
Abstract: It is challenging for selective catalytic reduction (SCR) of NOx by NH3 due to the co-existence of heavy metal and SO2 in the flue gas. The thorough probe into deactivation mechanisms is imperative...
75 citations
TL;DR: In this paper, the authors present an analysis of recent research works on NO3− reduction by the metallic catalysts, and discuss: (i) an assessment of various combinations of promoter and noble metals for mono-and bimetallic catalysts based on their reactivity and selectivity to N2; (ii) investigation of the reaction mechanism; (iii) evaluation of effect of diverse environmental factors on the performance of the catalyst; and (iv) stability and durability of the catalysts.
74 citations
TL;DR: An effective route to improve SO2 tolerance via modulating SO2 adsorption on Ce-based vanadate catalysts is demonstrated, which presented a new point for the development of high-performance SO2-tolerant SCR catalysts.
Abstract: SO2-tolerant selective catalytic reduction (SCR) of NOx at low temperature is still challenging. Traditional metal oxide catalysts are prone to be sulfated and the as-formed sulfates are difficult to decompose. In this study, we discovered that SO2 adsorption could be largely restrained over FeδCe1-δVO4 catalysts, which effectively restrained the deposition of sulfate species and endowed catalysts with strong SO2 tolerance at an extremely low temperature of 240 °C. The increasing oxygen vacancies, enhanced redox properties, and improved acidity contributed to the SCR activity of the FeδCe1-δVO4 catalyst. The reaction pathway changed from the reaction between bidentate nitrate and the NH3 species over CeVO4 catalysts via the Langmuir-Hinshelwood mechanism to that between gaseous NOx and the NH4+/NH3 species over FeδCe1-δVO4 catalysts via the Eley-Rideal mechanism. The effective suppression of SO2 adsorption allowed FeδCe1-δVO4 catalysts to maintain the Eley-Rideal pathways on account of the reduced formation of sulfate species. This work demonstrated an effective route to improve SO2 tolerance via modulating SO2 adsorption on Ce-based vanadate catalysts, which presented a new point for the development of high-performance SO2-tolerant SCR catalysts.
TL;DR: It was concluded that the hierarchically porous structure could not only improve the mass transfer of reactant/product but also provide larger specific surface area, higher surface acidity, larger NO adsorption capacity.
TL;DR: In this paper, the simultaneous control of toluene and NOx is investigated on a series of MnOx-CeO2 catalysts, in which NOx was removed in selective catalytic reduction with NH3 into N2, and tofluene was removed by catalytic combustion into CO2.
Abstract: The simultaneous control of toluene and NOx was investigated on a series of MnOx-CeO2 catalysts, in which NOx was removed in selective catalytic reduction with NH3 into N2, and toluene was removed in catalytic combustion into CO2. We identified the deactivation effect of the MnOx-CeO2 SCR catalyst in the presence of toluene. The NO conversion and N2 selectivity significantly decrease by 50 ppm toluene in the NH3-SCR feed gas. The competitive adsorption of toluene and the deposition of by-products on catalyst surface lead to a considerable decrease in NH3 adsorption. The formation of active Lewis acid sites are dramatically restrained. Meanwhile, the toluene adsorption promotes the formation of oxygen vacancies, increasing the unfavored oxidation reactions of NH3 (non-selective catalytic reduction, NSCR etc.) instead of standard SCR reaction, leading to a significantly decrease in the N2 selectivity. Toluene inhibits the low-temperature SCR activity over MnOx-CeO2 catalysts mainly through the Eley-Rideal mechanism.
TL;DR: The immobilization of ultra-fine Ag nanoparticles and the extremely negative potentials around MCS nanocomposites, which were effective for the diffusion of reactants, synergistically accelerated the catalytic reduction reactions.
TL;DR: In this article, the NH3 (NH3-SCR) over the V2O5-WO3/TiO2 catalyst is the state-of-the-art technology for NOx removal from both stationary and mobile sources.
Abstract: The selective catalytic reduction of NOx by NH3 (NH3–SCR) over the V2O5–WO3/TiO2 catalyst is the state-of-the-art technology for NOx removal from both stationary and mobile sources. Phosphorus can ...
TL;DR: In this paper, the NH3-selective catalytic reduction (SCR) catalysts were deactivated due to NH4HSO4 deposition at low temperatures due to the NH4 HSO4 degradation.
Abstract: The deactivation of NH3-selective catalytic reduction (SCR) catalysts due to NH4HSO4 deposition at low temperatures (
TL;DR: In this paper, a series of Sm modified Mn/TiO2 catalysts were proposed for selective catalytic reduction of NO with NH3 and their catalytic activity was evaluated at low temperature.
Abstract: A series of Sm modified Mn/TiO2 catalysts were proposed for selective catalytic reduction of NO with NH3 and their catalytic activity was evaluated at low temperature. The effect of Sm on the catalytic activity of Mn-Sm/TiO2 was comprehensively studied using XRD, low-temperature N2 adsorption, XPS, NH3-TPD and H2-TPR. The results showed that the 20Mn-10Sm/TiO2 catalyst, prepared by ultrasonic impregnation, exhibited NOx conversion of higher than 80 % at the temperature range of 110–250 °C with a gas hourly space velocity of 80,000 h−1. The weak Lewis acid site and redox ability may be crucial properties for catalytic performance as a result of the increase of Mn4+ and surface chemisorption oxygen as well as weak acid sites due to the enhanced interaction among Mn, Sm and Ti after addition of Sm. The in situ DRIFTS experiments were conducted to investigate the adsorption of NH3 and NO with their surface reaction. The results revealed that the SCR reactions on the surface of Mn/TiO2 catalyst follow both Langmuir-Hinshelwood and Eley-Rideal mechanism and bridging nitrate is the important intermediate. While, that on surface of 20Mn-10Sm/TiO2 catalyst comply with only Eley-Rideal mechanism, as the introduction of Sm changes the reaction path by inhibiting the adsorption of NO in the presence of NH3. Besides, SCR reaction rate over 20Mn-10Sm/TiO2 catalyst is fast as a result of large amount of -NH2 species formed on the surface of 20Mn-10Sm/TiO2 catalyst for the breaking of N H bonds become easier over the Sm modified catalyst, which is beneficial for SCR activity of 20Mn-10Sm/TiO2 catalyst at low temperature. The TG-DSC-MS results revealed that the addition of Sm reduce the sulfation of Mn/TiO2 catalyst.
TL;DR: In this paper, a review of the applications of various cerium-based oxides in gaseous pollutant control are systematically reviewed, including selective catalytic reduction (SCR) of NOx with NH3, adsorption and catalytic oxidation of Hg0, CO oxidation, CO2 conversion, selective oxidization of H2S, and catalyst combustion of volatile organic compounds (VOCs).
TL;DR: This work illustrates the power of precise control over a catalytic material, simultaneous kinetic and spectroscopic interrogation over a wide range of reaction conditions, and computational strategies tailored to capture those reaction conditions to reveal in microscopic detail the mechanistic features of a complex and widely practiced catalysis.
Abstract: ConspectusCopper-exchanged chabazite (Cu-CHA) zeolites are catalysts used in diesel emissions control for the abatement of nitrogen oxides (NOx) via selective catalytic reduction (SCR) reactions wi...
TL;DR: In this article, a sulfation strategy that can tune the surface acid sites and regulate the electronic state of nano-CeO2 was proposed to improve the reactivity of Ce-based materials for selective catalytic reduction of NOx with NH3.
TL;DR: This work proposes a novel self-protected anti-poisoning mechanism derived from the migration of sulfate in SO42-/TiO2 superacid to resist alkali and heavy metals and provides a new avenue for designing novel catalysts with outstanding resistance to alkaliand heavy metals.
Abstract: Reducing the poisoning effect of alkali and heavy metals over ammonia selective catalytic reduction (NH3-SCR) catalysts is still an intractable issue, as the presence of K and Pb in fly ash greatly...
TL;DR: In this paper, a ball-flower-like catalyst (CoMnOx-BF) was developed by hydrothermal method for the selective catalytic reduction (SCR) of NOx by NH3.
TL;DR: It was noted that the loading of excessive Pb could change the reaction route over the VWT catalyst, leading to low CB oxidation efficiency and CO2 selectivity, but these Pb spices likely acted as "a sink" to capture the dissociated Cl that hindered the electrophilic chlorination reaction, and avoided the formation of more toxic polychlorinated byproducts.
TL;DR: In this article, a NbOPO4-supported Cu-Ce-Nb-P catalyst was employed for selective catalytic reduction (SCR) of NO by NH3.
TL;DR: The development of highly active catalysts for ammonia selective catalytic reduction (NH3-SCR) of NO at low temperatures and the exploration of efficient catalytic active sites are desirable but st...
Abstract: The development of highly active catalysts for ammonia selective catalytic reduction (NH3-SCR) of NO at low temperatures and the exploration of efficient catalytic active sites are desirable but st...
TL;DR: In this article, an improved reduction of NOx with NH3 in the presence of alkali metal ions over novel Fe-doped manganese oxide octahedral molecular sieve (OMS-2) catalysts has been demonstrated and the promotional effects of Fe have been clarified.
TL;DR: In this article, a comprehensive overview of the selective catalytic reduction system operation together with their component's progress was reviewed, and a critical interpretative investigation about the common relation among the various catalysts is utilized in the ammonia selective catalytic reduction system using principal component analysis.
TL;DR: In this paper, a series of CuAl-layered double oxide/carbon nanotubes-x (CuAl-LDO/CNTs-x) nanocatalysts with a tunable valence distribution of highly dispersed CuOx species was constructed from the topotactic transformation of the precursors and a controllable carbothermal reduction reaction.
TL;DR: A novel Ti doped Sm-Mn mixed oxide catalyst designed for the selective catalytic reduction (SCR) of NOx with NH3 at low temperature exhibited superior performance, and was conducive to the reasonable design of low temperature NH3-SCR catalysts generated by adjusting fabrication.
Abstract: A novel Ti-doped Sm-Mn mixed oxide (TiSmMnOx) was first designed for the selective catalytic reduction (SCR) of NOx with NH3 at a low temperature. The TiSmMnOx catalyst exhibited a superior catalytic performance, in which NOx conversion higher than 80% and N2 selectivity above 90% could be achieved in a wide-operating temperature window (60-225 °C). Specially, the catalyst also showed high durability against the large space velocity and excellent SO2/H2O resistance. Ti incorporation can efficiently inhibit MnOx crystallization and tune the MnOx phase during calcination at a high temperature. Subsequently, a high specific surface area as well as an increased amount of acid sites on the TiSmMnOx catalysts were produced. Further, the reducibility of the Sm-doped MnOx catalyst was modulated, facilitating NO oxidation and inhibiting NH3 nonselective oxidation. Consequently, a superior SCR activity was achieved at a low temperature and the operating temperature window of the TiSmMnOx catalyst was significantly widened. These findings may provide new insights into the reasonable design and development of the new non-vanadium catalysts with a high NH3-SCR activity for industrial application.
TL;DR: In this article, a comprehensive review on the application of noble metal-based catalysts in the NH3-SCO reaction is presented, which sheds light on the rational catalyst design and in understanding the structure-property relationships of noble-metal-based SCO catalysts.