scholarly journals Highly porous Ce–W–TiO2 free-standing electrospun catalytic membranes for efficient de-NOxvia ammonia selective catalytic reduction

2019 ◽  
Vol 6 (1) ◽  
pp. 94-104 ◽  
Author(s):  
Apiwat Dankeaw ◽  
Fabrizio Gualandris ◽  
Rafael Hubert Silva ◽  
Roberto Scipioni ◽  
Kent Kammer Hansen ◽  
...  
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Free Standing ◽  
Catalytic Membranes ◽  
Scr Catalysts ◽  
Polymeric Component ◽  
Highly Porous

Highly porous free-standing ceramic SCR catalysts are achieved by via integrating a co-electrospun supporting polymeric component.

scholarly journals A review of Mn-containing oxide catalysts for low temperature selective catalytic reduction of NOx with NH3: reaction mechanism and catalyst deactivation

RSC Advances ◽  
2017 ◽  
Vol 7 (42) ◽  
pp. 26226-26242 ◽  
Author(s):  
Shengen Zhang ◽  
Bolin Zhang ◽  
Bo Liu ◽  
Shuailing Sun
Keyword(s):  
Reaction Mechanism ◽  
Low Temperature ◽  
Selective Catalytic Reduction ◽  
Catalyst Deactivation ◽  
Catalytic Reduction ◽  
Oxide Catalysts ◽  
Scr Catalysts ◽  
Reduction Of Nox

The reactions over Mn-containing selective catalytic reduction (SCR) catalysts.

Insights into sulfur poisoning and regeneration of Cu-SSZ-13 catalysts: In situ Cu and S K-edge XAS studies

2021 ◽  
Author(s):  
Vitaly Mesilov ◽  
Sandra Dahlin ◽  
Susanna Liljegren Bergman ◽  
Peter Sams Hammershøi ◽  
Shibo Xi ◽  
...  
Keyword(s):  
Selective Catalytic Reduction ◽  
Oxidation State ◽  
Absorption Spectroscopy ◽  
Catalytic Reduction ◽  
Sulfur Poisoning ◽  
X Ray ◽  
Scr Catalysts ◽  
X Ray Absorption

In situ Cu and S K-edge X-ray absorption spectroscopy (XAS) was used for the investigation of sulfur-poisoned and regenerated Cu-SSZ-13 selective catalytic reduction (SCR) catalysts. Sulfur in the oxidation state...

Iron-exchanged high-silica LTA zeolites as hydrothermally stable NH3-SCR catalysts

2019 ◽  
Vol 4 (6) ◽  
pp. 1050-1058 ◽  
Author(s):  
Taekyung Ryu ◽  
Yonjoo Kang ◽  
In-Sik Nam ◽  
Suk Bong Hong
Keyword(s):  
High Activity ◽  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Hydrothermal Aging ◽  
Reduction Of No ◽  
Nh3 Scr ◽  
Scr Catalysts ◽  
High Silica

Iron-exchanged high-silica LTA zeolites exhibit high activity for selective catalytic reduction of NOx by NH3, even after hydrothermal aging at 900 °C.

scholarly journals Novel Catalysts for Selective Catalytic Reduction of NOx by NH3 Prepared by Atomic Layer Deposition of V and Ti Oxides on SiO2 Powder

2020 ◽  
Vol 2 (1) ◽  
pp. 33
Author(s):  
Davyd Urbanas ◽  
Pranas Baltrėnas ◽  
Saeed Saedy ◽  
Aristeidis Goulas ◽  
J. Ruud van Ommen
Keyword(s):  
Nitrogen Oxides ◽  
Atomic Layer Deposition ◽  
Specific Surface ◽  
Selective Catalytic Reduction ◽  
Surface Area ◽  
Catalytic Reduction ◽  
Atomic Layer ◽  
Nh3 Scr ◽  
Layer Deposition ◽  
Highly Porous

Based on the 2019 report of the European Environment Agency on Air Quality in Europe nitrogen oxides (NOx) were identified as the most harmful air pollutants in terms of damage to ecosystems. Moreover, in Europe, NO2 is pinpointed as one of the most dangerous pollutants for human health. Anthropogenic emissions of NOx are mainly generated by the combustion of fossil fuels. Nitrogen oxides being emitted into the atmosphere cause environmental problems such as acid rain, acidification of soil, lakes and rivers, eutrophication and photochemical smog. The most effective and widely applicable technology to date for the purification of flue gases from NOx is selective catalytic reduction using ammonia (NH3-SCR de-NOx). Nowadays, one of the most significant research fields in NH3-SCR de-NOx is the application of unconventional reduction methods and the preparation of novel catalysts possessing high specific surface area, uniformity, dispersion of active sites, activity and selectivity. Atomic layer deposition (ALD) is an attractive technique for the deposition of uniformly distributed active catalytic layers, or nanoparticles, on highly porous substrates characterized by a complex structure. For this type of materials, conventional catalyst preparation methods (e.g., impregnation or deposition precipitation) can encounter several limitations. The significant advantage of ALD for the preparation of supported catalysts is that the process can be controlled on the atomic scale, providing the required thickness of an active layer, synthesized with a sub-nm accuracy. Moreover, ALD ensures the formation of catalytic sites from the gas phase, which enhances the possibility of active species being deposited inside pores which are very small in size. In this study, ALD was applied to the preparation of VxOy-based NH3-SCR de-NOx catalysts. Highly porous silica gel powder (63–100 μm) with a specific surface area of up to 450 m2·g−1 was used as a substrate for VxOy/SiO2 with different metal loadings (wt.%). In addition (VxOy+TiO2)/SiO2 catalysts were prepared by applying vanadium (V) tri-i-propoxy oxide (VTIP) and titanium tetrachloride (TiCl4) as precursors with deionized water as the co-reactant. Elemental analysis (ICP-OES) revealed that vanadium loadings of the VxOy/SiO2 catalysts were 0.3, 0.7, 1.1 and 1.60 wt.%, while the loadings in the TiO2-promoted VxOy/SiO2 catalyst were 1.0 and 0.2 wt.% for V and Ti, respectively. The obtained XPS spectra indicated the presence of V2O3 and V2O5 species (V2O5/V2O3 ratio was 1.6 and 6.3 for the as-synthesized and calcined samples respectively). Vanadium(V) oxide is known to be a catalytically active compound for NH3-SCR de-NOx. Additionally, TEM, XRD and N2 adsorption (BET) analyses were conducted to provide a comprehensive characterization of the species size, crystalline phase and porosity of the catalysts prepared.

scholarly journals Radio-Frequency-Based NH3-Selective Catalytic Reduction Catalyst Control: Studies on Temperature Dependency and Humidity Influences

Sensors ◽  
2017 ◽  
Vol 17 (7) ◽  
pp. 1615 ◽  
Author(s):  
Markus Dietrich ◽  
Gunter Hagen ◽  
Willibald Reitmeier ◽  
Katharina Burger ◽  
Markus Hien ◽  
...  
Keyword(s):  
Radio Frequency ◽  
Selective Catalytic Reduction ◽  
New Technologies ◽  
Catalytic Reduction ◽  
Special Focus ◽  
Temperature Range ◽  
Scr Catalysts ◽  
Rf Signals ◽  
High Space ◽  
First Time

The upcoming more stringent automotive emission legislations and current developments have promoted new technologies for more precise and reliable catalyst control. For this purpose, radio-frequency-based (RF) catalyst state determination offers the only approach for directly measuring the NH3 loading on selective catalytic reduction (SCR) catalysts and the state of other catalysts and filter systems. Recently, the ability of this technique to directly control the urea dosing on a current NH3 storing zeolite catalyst has been demonstrated on an engine dynamometer for the first time and this paper continues that work. Therefore, a well-known serial-type and zeolite-based SCR catalyst (Cu-SSZ-13) was investigated under deliberately chosen high space velocities. At first, the full functionality of the RF system with Cu-SSZ-13 as sample was tested successfully. By direct RF-based NH3 storage control, the influence of the storage degree on the catalyst performance, i.e., on NOx conversion and NH3 slip, was investigated in a temperature range between 250 and 400 °C. For each operation point, an ideal and a critical NH3 storage degree was found and analyzed in the whole temperature range. Based on the data of all experimental runs, temperature dependent calibration functions were developed as a basis for upcoming tests under transient conditions. Additionally, the influence of exhaust humidity was observed with special focus on cold start water and its effects to the RF signals.

scholarly journals Fe-Exchanged Small-Pore Zeolites as Ammonia Selective Catalytic Reduction (NH3-SCR) Catalysts

Catalysts ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1324
Author(s):  
Feng Gao
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Short Review ◽  
Industrial Applications ◽  
Zeolite Catalysts ◽  
Hydrothermal Aging ◽  
Theoretical Approaches ◽  
Fe Species ◽  
Scr Catalysts ◽  
Small Pore

Cu-exchanged small-pore zeolites have been extensively studied in the past decade as state-of-the-art selective catalytic reduction (SCR) catalysts for diesel engine exhaust NOx abatement for the transportation industry. During this time, Fe-exchanged small-pore zeolites, e.g., Fe/SSZ-13, Fe/SAPO-34, Fe/SSZ-39 and high-silica Fe/LTA, have also been investigated but much less extensively. In comparison to their Cu-exchanged counterparts, such Fe/zeolite catalysts display inferior low-temperature activities, but improved stability and high-temperature SCR selectivities. Such characteristics entitle these catalysts to be considered as key components of highly efficient emission control systems to improve the overall catalyst performance. In this short review, recent studies on Fe-exchanged small-pore zeolite SCR catalysts are summarized, including (1) the synthesis of small-pore Fe/zeolites; (2) nature of the SCR active Fe species in these catalysts as determined by experimental and theoretical approaches, including Fe species transformation during hydrothermal aging; (3) SCR reactions and structure-function correlations; and (4) a few aspects on industrial applications.

scholarly journals Selective Catalytic Reduction of NOx over V2O5-WO3-TiO2 SCR Catalysts—A Study at Elevated Pressure for Maritime Pre-turbine SCR Configuration

2019 ◽  
Vol 5 (3) ◽  
pp. 263-278 ◽  
Author(s):  
Steen R. Christensen ◽  
Brian B. Hansen ◽  
Kim H. Pedersen ◽  
Joakim R. Thøgersen ◽  
Anker D. Jensen
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Elevated Pressure ◽  
Scr Catalysts ◽  
Reduction Of Nox
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