scholarly journals The Impact of Pressure and Hydrocarbons on NOx Abatement over Cu- and Fe-Zeolites at Pre-Turbocharger Position

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 336
Author(s):  
Deniz Zengel ◽  
Simon Barth ◽  
Maria Casapu ◽  
Jan-Dierk Grunwaldt
Keyword(s):  
Catalytic Reduction ◽  
Elevated Pressure ◽  
Systematic Investigation ◽  
Diesel Oxidation Catalyst ◽  
Zeolite Catalysts ◽  
Oxidation Catalyst ◽  
Pollutant Concentrations ◽  
Oxidation Of Hydrocarbons ◽  
Negative Effect ◽  
The Impact

Positioning the catalysts in front of the turbocharger has gained interest over recent years due to the earlier onset temperature and positive effect of elevated pressure. However, several challenges must be overcome, like presence of higher pollutant concentrations due to the absence or insufficient diesel oxidation catalyst volume at this location. In this context, our study reports a systematic investigation on the effect of pressure and various hydrocarbons during selective catalytic reduction (SCR) of NOx with NH3 over the zeolite-based catalysts Fe-ZSM-5 and Cu-SSZ-13. Using a high-pressure catalyst test bench, the catalytic activity of both zeolite catalysts was measured in the presence and absence of a variety of hydrocarbons under pressures and temperatures resembling the conditions upstream of the turbocharger. The results obtained showed that the hydrocarbons are incompletely converted over both catalysts, resulting in numerous byproducts. The emission of hydrogen cyanide seems to be particularly problematic. Although the increase in pressure was able to improve the oxidation of hydrocarbons and significantly reduce the formation of HCN, sufficiently low emissions could only be achieved at high temperatures. Regarding the NOx conversion, a boost in activity was obtained by increasing the pressure compared to atmospheric reaction conditions, which compensated the negative effect of hydrocarbons on the SCR activity.

scholarly journals New Insight into the In Situ SO2 Poisoning Mechanism over Cu-SSZ-13 for the Selective Catalytic Reduction of NOx with NH3

Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1391
Author(s):  
Yu Qiu ◽  
Chi Fan ◽  
Changcheng Sun ◽  
Hongchang Zhu ◽  
Wentian Yi ◽  
...  
Keyword(s):  
Selective Catalytic Reduction ◽  
Active Sites ◽  
Catalytic Reduction ◽  
Zeolite Catalysts ◽  
So2 Poisoning ◽  
Negative Effect ◽  
Temperature Programmed ◽  
Diffuse Reflectance Infrared ◽  
Sulfate Species

To reveal the nature of SO2 poisoning over Cu-SSZ-13 catalyst under actual exhaust conditions, the catalyst was pretreated at 200 and 500 °C in a flow containing NH3, NO, O2, SO2, and H2O. Brunner−Emmet−Teller (BET), X-ray diffraction(XRD), thermo gravimetric analyzer (TGA), ultraviolet Raman spectroscopy (UV Raman), temperature-programmed reduction with H2 (H2-TPR), temperature-programmed desorption of NO+O2 (NO+O2-TPD), NH3-TPD, in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS), and an activity test were utilized to monitor the changes of Cu-SSZ-13 before and after in situ SO2 poisoning. According to the characterization results, the types and generated amount of sulfated species were directly related to poisoning temperature. Three sulfate species, including (NH4)2SO4, CuSO4, and Al2(SO4)3, were found to form on CZ-S-200, while only the latter two sulfate species were observed over CZ-S-500. Furthermore, SO2 poisoning had a negative effect on low-temperature selective catalytic reduction (SCR) activity, which was mainly due to the sulfation of active sites, including Z2Cu, ZCuOH, and Si-O(H)-Al. In contrast, SO2 poisoning had a positive effect on high-temperature SCR activity, owing to the inhibition of the NH3 oxidation reaction. The above findings may be a useful guideline to design excellent SO2-resistant Cu-based zeolite catalysts.

A Physically-Based, Control-Oriented Diesel Particulate Filter (DPF) Model for the Applications of NO/NO2 Ratio Estimation Using a NOx Sensor

2010 ◽  
Author(s):  
Ming-Feng Hsieh ◽  
Junmin Wang
Keyword(s):  
Diesel Particulate Filter ◽  
Catalytic Reduction ◽  
Nox Reduction ◽  
Diesel Oxidation Catalyst ◽  
Oxidation Catalyst ◽  
Particulate Filter ◽  
Exhaust Gas ◽  
Diesel Particulate ◽  
Physically Based ◽  
Aftertreatment Systems

This paper presents a physically-based, control-oriented Diesel particulate filter (DPF) model for the purposes of NO and NO2 concentration estimations in Diesel engine aftertreatment systems. The presence of NO2 in exhaust gas plays an important role in selective catalytic reduction (SCR) NOx reduction efficiency. However, current NOx cannot differentiate NO and NO2 from the total NOx concentration. A model which can be used to estimate NO and NO2concentrations in exhaust gas flowing into the SCR catalyst is thus necessary. Current aftertreatment systems for light-, medium-, and heavy-duty Diesel engines generally include Diesel oxidation catalyst (DOC), DPF, and SCR. The DPF related NO/NO2 dynamics was investigated in this study, and a control-oriented model was developed and validated with experimental data.

NO and NO2 Concentration Modeling and Observer-Based Estimation Across a Diesel Engine Aftertreatment System

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Ming-Feng Hsieh ◽  
Junmin Wang
Keyword(s):  
Diesel Engine ◽  
Catalytic Reduction ◽  
Diesel Oxidation Catalyst ◽  
Equation Model ◽  
Oxidation Catalyst ◽  
Particulate Filter ◽  
Exhaust Gas ◽  
Aftertreatment System ◽  
Stirred Tank Reactors ◽  
Aftertreatment Systems

This paper presents an experimentally validated control-oriented model and an observer for diesel oxidation catalyst (DOC)-diesel particulate filter (DPF) system in the context of exhaust gas NO and NO2 concentration estimations. NO and NO2 have different reaction characteristics within DPF and selective catalytic reduction (SCR) systems, two most promising diesel engine aftertreatment systems. Although the majority of diesel engine-out NOx emissions is NO, the commonly used DOC located upstream of a DPF and a SCR can convert a considerable amount of NO to NO2. Knowledge of the NO/NO2 ratio in exhaust gas is thus meaningful for the control and diagnosis of DPF and SCR systems. Existing onboard NOx sensors cannot differentiate NO and NO2, and such a sensory deficiency makes separate considerations of NO and NO2 in SCR control design challenging. To tackle this problem, a control-oriented dynamic model, which can capture the main NO and NO2 dynamics from engine-out, through DOC, and to DPF, was developed. Due to the computational limitation concerns, DOC and DPF are assumed to be standard continuously stirred tank reactors in order to obtain a 0D ordinary differential equation model. Based on the model, an observer, with the measurement from a commercially available NOx sensor, was designed to estimate the NO and NO2 concentrations in the exhaust gas along the aftertreatment systems. The stability of the observer was shown through a Lyapunov analysis assisted by insight into the system characteristics. The control-oriented model and the observer were validated with engine experimental data and the measured NO/NO2 concentrations by a Horiba gas analyzer. Experimental results show that the model can accurately predict the main engine-out/DOC/DPF NO/NO2 dynamics very well in semisteady-state tests. For the proposed observer, the predictions converge to the model values and estimate the NO and NO2 concentrations in the aftertreatment system well.

scholarly journals Assessment of the Impact of Trace Elements in FAME Biodiesel on Diesel Oxidation Catalyst Activity after Full Lifetime of Operation in A Heavy-Duty Truck

Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1439
Author(s):  
Jonas Granestrand ◽  
Rodrigo Suárez París ◽  
Marita Nilsson ◽  
Francesco Regali ◽  
Lars Pettersson
Keyword(s):  
Trace Elements ◽  
Catalyst Activity ◽  
Acid Methyl Ester ◽  
Diesel Oxidation Catalyst ◽  
Oxidation Catalyst ◽  
Heavy Duty ◽  
Heavy Duty Truck ◽  
Diesel Oxidation ◽  
The Impact ◽  
Element Removal

Fatty acid methyl ester (FAME) biodiesel contains some trace amounts of Na, K, P, Ca, and Mg. Our objective was to investigate whether the presence of such elements can poison a diesel oxidation catalyst that has been used for an entire regulatory lifetime in a heavy-duty truck fueled by FAME biodiesel. The investigated vehicle-aged catalyst contained high loadings of S, P, and Na, as well as a visible layer of soot. Activity in the NO oxidation reaction was severely decreased compared to a fresh catalyst of the same type, while the CO and C3H6 oxidation reactions were less affected. Subsequent selective trace element removal procedures, followed by activity tests, were used to decouple the effect of different poisons. Sintering was observed to be the main cause of catalyst deactivation. Of the trace elements present on the catalyst, P had the greatest effect on catalyst activity, while the other trace elements had little effect.

The impact of CO and C3H6 pulses on PtO reduction and NO oxidation in a diesel oxidation catalyst

2016 ◽  
Vol 181 ◽  
pp. 644-650 ◽  
Author(s):  
Adéla Arvajová ◽  
Petr Kočí ◽  
Volker Schmeißer ◽  
Michel Weibel
Keyword(s):  
Diesel Oxidation Catalyst ◽  
No Oxidation ◽  
Oxidation Catalyst ◽  
Diesel Oxidation ◽  
The Impact

scholarly journals Accelerated performance and durability test of the exhaust aftertreatment system by contaminated biodiesel

2017 ◽  
Vol 18 (10) ◽  
pp. 1067-1076 ◽  
Author(s):  
Jörg Schröder ◽  
Franziska Hartmann ◽  
Robert Eschrich ◽  
Denis Worch ◽  
Jürgen Böhm ◽  
...  
Keyword(s):  
Selective Catalytic Reduction ◽  
Alternative Fuels ◽  
Test Bench ◽  
Catalytic Reduction ◽  
Diesel Oxidation Catalyst ◽  
Oxidation Catalyst ◽  
Exhaust Aftertreatment ◽  
Aftertreatment System ◽  
Exhaust Aftertreatment System ◽  
Diesel Oxidation

The consumption of fossil and especially alternative fuels from renewable sources is supposed to rise in the future. Biofuels as well as fossil fuels often contain alkali and alkaline earth metal impurities that are potential poisons for automotive exhaust catalysts. The impact of these contaminations on the long-time performance of the exhaust aftertreatment system is a major concern. However, engine test bench studies consume considerable amounts of fuel, manpower and time. The purpose of this research project was to examine whether accelerated engine tests can be achieved by a modified diesel aftertreatment system in a test bench and contamination of biodiesel with known amounts of elements potentially poisoning automotive catalysts. A variety of potentially harmful elements (sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S) and phosphorous (P)) were added all at once to enhance the contamination level in biodiesel. A diesel oxidation catalyst and a catalyst for selective catalytic reduction reaction were placed in a stream of exhaust gas generated with a single cylinder engine. For reference purposes, a second test series was performed with a commercially available biodiesel. Catalysts were analyzed post-mortem using a bench flow reactor and X-ray fluorescence regarding their activity and deposition of the harmful elements. For both diesel oxidation catalyst and selective catalytic reduction catalysts, significant deactivation and decrease in conversion rates could be proven. For diesel oxidation catalyst, linear correlations between mass fractions of added elements and aging time were observed.

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