Hydrocarbon catalyzed-selective catalytic reduction catalysts using core-shell atomic layer deposited CeO2 and ZrO2

2019 ◽  
Vol 37 (2) ◽  
pp. 020919 ◽  
Author(s):  
David H. K. Jackson ◽  
Michael M. Schwartz ◽  
Chilan Ngo ◽  
Dustin Facteau ◽  
Svitlana Pylypenko ◽  
...  
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Atomic Layer ◽  
Core Shell ◽  
Reduction Catalysts

Experimental and kinetic analysis of hydrothermal aging effects on ammonia adsorption capacity over a commercial Cu-zeolite selective catalytic reduction catalyst

2018 ◽  
Vol 233 (12) ◽  
pp. 3030-3042
Author(s):  
Tae Joong Wang ◽  
In Hyuk Im
Keyword(s):  
Adsorption Capacity ◽  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Adsorption Site ◽  
Selective Catalytic Reduction Catalyst ◽  
Aging Effects ◽  
Hydrothermal Aging ◽  
Ammonia Adsorption ◽  
Fresh Catalyst ◽  
Reduction Catalysts

Ammonia/urea selective catalytic reduction is an efficient technology to control NOx emission from diesel engines. One of its critical challenges is the performance degradation of selective catalytic reduction catalysts due to the hydrothermal aging experienced in real-world operations during the lifetime. In this study, hydrothermal aging effects on the reduction of ammonia adsorption capacity over a commercial Cu-zeolite selective catalytic reduction catalyst were investigated under actual engine exhaust conditions. Ammonia adsorption site densities of the selective catalytic reduction catalysts aged at two different temperatures of 750°C and 850°C for 25 h with 10% H2O were experimentally measured and compared to that of fresh catalyst on a dynamometer test bench with a heavy-duty diesel engine. The test results revealed that hydrothermal aging significantly decreased the ammonia adsorption capacity of the current commercial Cu-zeolite selective catalytic reduction catalyst. Hydrothermal treatment at 750°C reduced the ammonia adsorption site to 62.5% level of that of fresh catalyst, while hydrothermal treatment at 850°C lowered the adsorption site to 37.0% level of that of fresh catalyst. Also, in this study, numerical simulation and kinetic analysis were carried out to quantify the impact of hydrothermal aging on the reduction of ammonia adsorption capacity by introducing an aging coefficient. The kinetic parameter calibrations based on actual diesel engine tests with a commercial monolith Cu-zeolite selective catalytic reduction catalyst provided a highly realistic kinetic parameter set of ammonia adsorption/desorption and enabled a mathematical description of hydrothermal aging effect.

Selective reduction of nitrogen oxides (NOx) by ammonia over honeycomb selective catalytic reduction catalysts

1993 ◽  
Vol 32 (6) ◽  
pp. 1053-1060 ◽  
Author(s):  
Jiri Svachula ◽  
Natale Ferlazzo ◽  
Pio Forzatti ◽  
Enrico Tronconi ◽  
Fiorenzo Bregani
Keyword(s):  
Nitrogen Oxides ◽  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Selective Reduction ◽  
Reduction Catalysts

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.

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