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Simulation Of Nox Reduction Over A Fe Zeolite Catalyst In An Nh3 Scr System And Calibration Of The Related Parameters
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Book Synopsis Simulation of NOx Reduction Over a Fe-zeolite Catalyst in an NH3-SCR System and Calibration of the Related Parameters by : Leila Sharifian
Download or read book Simulation of NOx Reduction Over a Fe-zeolite Catalyst in an NH3-SCR System and Calibration of the Related Parameters written by Leila Sharifian and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Urea-SCR Technology for deNOx After Treatment of Diesel Exhausts by : Isabella Nova
Download or read book Urea-SCR Technology for deNOx After Treatment of Diesel Exhausts written by Isabella Nova and published by Springer Science & Business Media. This book was released on 2014-03-14 with total page 715 pages. Available in PDF, EPUB and Kindle. Book excerpt: Urea-SCR Technology for deNOx After Treatment of Diesel Exhausts presents a complete overview of the selective catalytic reduction of NOx by ammonia/urea. The book starts with an illustration of the technology in the framework of the current context (legislation, market, system configurations), covers the fundamental aspects of the SCR process (catalysts, chemistry, mechanism, kinetics) and analyzes its application to useful topics such as modeling of full scale monolith catalysts, control aspects, ammonia injections systems and integration with other devices for combined removal of pollutants.
Book Synopsis Experimental and Kinetic Modeling Studies of Selective Catalytic Reduction of NOx with NH3 on Fe- and Cu-Zeolite Monolithic Catalysts by : Pranit Subhash Metkar
Download or read book Experimental and Kinetic Modeling Studies of Selective Catalytic Reduction of NOx with NH3 on Fe- and Cu-Zeolite Monolithic Catalysts written by Pranit Subhash Metkar and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The selective catalytic reduction (SCR) of NOx with NH3 is considered to be the most promising technique for the efficient reduction of highly detrimental NOx (to N2) emitted from diesel engine vehicles. Amongst the various catalysts available for SCR, Fe- and Cu-zeolite catalysts are found to be highly stable and efficient towards maximum NOx reduction over a wide temperature range. Cu-zeolites are more active at low temperatures ( 350 oC) while Fe-zeolites are more active at high temperatures ( 400 oC). We carried out a comprehensive experimental and kinetic modeling study of key SCR reactions on Fe- and Cu-zeolite catalysts and present a detailed understanding of mass transfer limitations and kinetics and mechanistic aspects of various SCR reactions on these catalysts. Experiments carried out on monolith catalysts having different washcoat loadings, washcoat thicknesses and lengths indicate the presence of washcoat (or pore) diffusion limitations at intermediate to high temperature range in all the SCR reactions. A detailed analysis of the effect of temperature on the transitions between various controlling regimes (kinetic, washcoat diffusion and external mass transfer) is presented. Agreement in the differential kinetics studies of NO oxidation and standard SCR (NO + O2 + NH3) reactions indicates NO oxidation is the rate determining step for standard SCR. A detailed kinetic model capturing key features of all the SCR reactions is developed. This model accurately predicts the experimentally observed NOx conversions over a wide temperature range and different feed conditions. Finally, a systematic study of various SCR reactions is carried out on a combined system of Fe- and Cu-zeolite monolithic catalysts to determine if a high NOx conversion could be sustained over a wider temperature range than with individual Fe- and Cu-zeolite catalysts. Amongst various configurations, a dual-layer catalyst with a thin Fe-zeolite layer on top of a thick Cu-zeolite layer resulted in a very high NOx removal efficiency over a broad temperature range of practical interest. The kinetic model accurately captures the experimental data with a combined system of Fe- and Cu-zeolite catalysts and provides further insights into the catalyst arrangements for maximum NOx reduction efficiency.
Book Synopsis IR Spectroscopy Based Kinetic Modeling of NH3-SCR on Fe-zeolites by : Stavros Skarlis
Download or read book IR Spectroscopy Based Kinetic Modeling of NH3-SCR on Fe-zeolites written by Stavros Skarlis and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Selective Catalytic Reduction of nitrogen oxides through urea or ammonia is a well established technique for the efficient abatement of NOx, from mobile diesel engines exhaust stream. Among catalytic formulations proposed, Fe-exchanged zeolites are considered as promising SCR catalysts, due to their enhanced deNOx performance over a broad range of operating temperatures, as well as significant resistance to hydrothermal ageing. In the present work, detailed experimental investigation of the NH3-SCR reactions network over Fe zeolites was performed in order to develop a phenomenological macro-kinetic model oriented to diesel engines aftertreatment system simulation. Dedicated experiments, including IR spectroscopy measurements were performed over lab-synthesized H- and Fe-BEA catalysts in order to unravel mechanistic aspects related to the formation and interactions of ammonia and nitrogen oxides adspecies (namely nitrate and nitrites) on acidic and redox catalytic sites. Formation and decomposition of NH4NO3 was of particular concern. Based on experimental results a multi-site kinetic model was developed, which was able to account for surface acidity variation, interactions of gaseous NH3 and NOx species with iron sites, as well as low temperature physisorption phenomena. The model was successfully validated through simulation of experiments performed over various Fe-zeolite samples, applying a broad range of operating conditions, which showed the interest of the followed approach.
Book Synopsis Studies of Platinum Dispersion and Catalyst Architecture for Lean NOx Reduction by : Bijesh Man Shakya
Download or read book Studies of Platinum Dispersion and Catalyst Architecture for Lean NOx Reduction written by Bijesh Man Shakya and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The combination of NOx storage and reduction (NSR) and selective catalytic reduction (SCR) catalyst is a promising technology for the reduction of NOx emission from the exhaust of lean-burn or diesel engine vehicles. In the combined NSR/SCR system, NH3 generated in LNT during the rich phase is utilized in the SCR for additional NOx conversion. Therefore, the performance of the combined NSR/SCR depends strongly on the NH3 generating function of the NSR catalyst. Earlier studies show that lower Pt dispersion NSR catalysts give higher selectivity to NH3 making them ideal candidates for this particular application. In the first part of the work, we performed experiments on lower Pt dispersion catalysts to gain insights on the mechanistic effects of Pt dispersion on NOx conversion and selectivity. We also developed an improved crystallite-scale model of NSR that explicitly accounts for the crystallite scale gradients of the stored NOx. The calibrated model is able to capture the effects of Pt dispersion, rich phase duration and overall cycle time on cycle-averaged conversion and selectivity trends. In the second part, we carried out a simulation study of dual-layer NSR+SCR monolithic catalyst using (1+1)-D model of catalytic monolith with individually-calibrated global kinetic models. Simulations show that multiple combinations of catalyst loading can attain a given NOx conversion and N2 selectivity, and that there exists a loading of SCR washcoat for a given NSR catalyst for which the NOx conversion is maximum. Simulations of the dual-brick monolith are also performed to analyze the effects of catalyst architecture. Under identical conditions, the simulations show that dual-layer catalyst outperforms the dual-brick largely because of the better utilization of generated NH3. Finally, we performed an optimization study to identify optimal loading and configuration of combined Fe+Cu zeolite catalyst that gives overall high NOx removal efficiency over a broad range of temperature. Simulations suggest that the brick configuration in which Fe- brick is followed by Cu- catalyst is slightly better than dual-layer in which Fe- is coated on top of Cu- architecture. This is attributed to the diffusional limitations in the washcoat that is more pronounced in the dual-layer catalysts.
Book Synopsis Selective Catalytic Reduction of NOx by : Oliver Kröcher
Download or read book Selective Catalytic Reduction of NOx written by Oliver Kröcher and published by MDPI. This book was released on 2018-12-14 with total page 281 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a printed edition of the Special Issue "Selective Catalytic Reduction of NOx" that was published in Catalysts
Book Synopsis AN EXPERIMENTAL INVESTIGATION OF THE EFFECT OF TEMPERATURE AND SPACE VELOCITY ON THE PERFORMANCE OF A CU-ZEOLITE FLOW-THROUGH SCR AND A SCR CATALYST ON A DPF WITH AND WITHOUT PM LOADING by :
Download or read book AN EXPERIMENTAL INVESTIGATION OF THE EFFECT OF TEMPERATURE AND SPACE VELOCITY ON THE PERFORMANCE OF A CU-ZEOLITE FLOW-THROUGH SCR AND A SCR CATALYST ON A DPF WITH AND WITHOUT PM LOADING written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : Abstract The heavy-duty diesel (HDD) engines use the diesel oxidation catalyst (DOC), catalyzed particulate filter (CPF) and urea injection based selective catalytic reduction (SCR) systems in sequential combination, to meet the US EPA 2010 PM and NOx emission standards. The SCR along with a NH3 slip control catalyst (AMOX) offer NOx reduction >90 % with NH3 slipHowever, there is a strong desire to further improve the NOx reduction performance of such systems, to meet the California Optional Low NOx Standard implemented since 2015. Integrating SCR functionality into a diesel particulate filter (DPF), by coating the SCR catalyst on the DPF, offers potential to reduce the system cost and packaging weight/ volume. It also provides opportunity to increases the SCR volume without affecting the overall packaging, to achieve NOx reduction efficiencies >95 %. xvii In this research, the NOx reduction and NH3 storage performance of a Cu-zeolite SCR and Cu-zeolite SCR catalyst on DPF (SCRF®) were experimentally investigated based on the engine experimental data at steady state conditions. The experimental data for the production-2013-SCR and the SCRF® were collected (with and without PM loading in the SCRF®) on a Cummins ISB 2013 engine, at varying inlet temperatures, space velocities, inlet NOx concentrations and NO2/NOx ratios, to evaluate the NOx reduction, NH3 storage and NH3 slip characteristics of the SCR catalyst. The SCRF® was loaded with 2 and 4 g/L of PM prior to the NOx reduction tests to study the effect of PM loading on the NOx reduction and NH3 storage performance of the SCRF®. The experimental setup and test procedures for evaluation of NOx reduction performance of the SCRF®, with and without PM loading in the SCRF® are described. The 1-D SCR model developed at MTU was calibrated to the engine experimental data obtained from the seven NOx reduction tests conducted with the production-2013-SCR. The performance of the 1-D SCR model was validated by comparing the simulation and experimental data for NO, NO2 and NH3 concentrations at the outlet of the SCR. The NO and NO2 concentrations were calibrated to ±20 ppm and NH3 was calibrated to ±20 ppm. The experimental results for the production-2013-SCR indicate that the NOx reduction of 80 - 85% can be achieved for the inlet temperatures below 250°C and above 450°C and NOx reduction of 90 - 95% can be achieved for the inlet temperatures between 300 - 350°C, at ammonia to NOx ratio (ANR) 1.0, while the NH3 slip out of the SCR wasConversely, the SCRF® showed 90 - 95 % NOx reduction at ANR of 1.0, while the NH3 slip out of the SCRF® was >50 ppm, with and without PM loading in the SCRF®, for the inlet temperature range of 200 - 450°C, space velocity in the range of 13 to 48 k/hr and inlet NO2/NOx in the range of 0.2 to 0.5. The NOx reduction in the SCRF® increases to >98 % at ANR 1.2. However, the NH3 slip out of the SCRF® increases significantly at ANR 1.2. xviii The effect of PM loading at 2 and 4 g/L on the NOx reduction performance of the SCRF® was negligible below 300°C. However, with PM loading in the SCRF®, the NOx reduction decreased by 3 - 5% when compared to the clean SCRF®, for inlet temperature >350°C. Experimental data were also collected by reference [1] to investigate the NO2 assisted PM oxidation in the SCRF® for the inlet temperature range of 260 - 370°C, with and without urea injection and thermal oxidation of PM in the SCRF® for the inlet temperature range of 500 - 600°C, without urea injection by reference [1]. The experimental data obtained from this study and [1] will be used to develop and calibrate the SCR-F model at Michigan Tech. The NH3 storage for the production-2013-SCR and the SCRF® (with and without PM loading) were determined from the steady state engine experimental data. The NH3 storage for the production-2013-SCR and the SCRF® (without PM loading) were within ±5 gmol/m3 of the substrate, with maximum NH3 storage of 75 - 80 gmol/m3 of the substrate, at the SCR/SCRF® inlet temperature of 200°C. The NH3 storage in the SCRF®, with 2 g/L PM loading, decreased by 30%, when compared to the NH3 storage in the SCRF®, without PM loading. The further increase in the PM loading in the SCRF®, from 2 to 4 g/L, had negligible effect on NH3 storage.
Book Synopsis Selective Catalytic Reduction of NOx by NH3 Over a Fe Zeolite Monolith Catalyst by : Nelson Salazar
Download or read book Selective Catalytic Reduction of NOx by NH3 Over a Fe Zeolite Monolith Catalyst written by Nelson Salazar and published by . This book was released on 2009 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Selective Catalytic Reduction of NOX by NH3 for Diesel Exhaust Aftertreatment by : Christopher Sokolowski
Download or read book Selective Catalytic Reduction of NOX by NH3 for Diesel Exhaust Aftertreatment written by Christopher Sokolowski and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The increasing price of liquid fuels and an increased focus on fuel efficiency has driven vehicle engine manufacturers toward diesel and other lean burn engines at the cost of increased emissions of nitrogen oxides (NOX), which contribute to pollution such as smog, ground level ozone, and acid deposition. Within the past thirty years, increasingly stringent NOX emission standards have forced engine manufacturers to develop novel ways to reduce these emissions. With the implementation of the latest American and European NOX emission standards, Selective Catalytic Reduction (SCR) has become the most prominent NOX reduction method in lean-burn engines.In the present work, a method is developed to test the performance of commercial SCR catalyst coated monoliths and probe the deactivation mechanisms. A monolith testing apparatus is constructed for these purposes. Necessary design features included a programmable gas mixing system, a steam generator, a temperature control system, and an analysis system based upon Fourier-transformed infrared spectroscopy. It is found that a high flow rate of carrier gas as well as a method to generate a water mist and prevent dripping is essential to ensure a stable supply of steam and repeatable results.Important SCR reactions, namely the standard, fast, and slow SCR reactions as well as NH3 adsorption and performance of a zeolite catalyst coated monolith were investigated at three temperatures -- 250 and 300 °C representing engine operation at normal operating conditions and 400 °C representing engine operation at high load. The amount of NH3 adsorbed decreased with temperature in line with previous studies while NOX reduction performance increased with higher temperatures at all inlet compositions tested. A transient drop in NO conversion performance was observed upon introduction of NH3 without the presence of NO2 consistent with previous studies suggesting an NH3 inhibition mechanism. When supplied with 1:1 and 1:3 ratios of NO:NO2 at 250 °C, the catalyst reduced more NOX than NH3 suggesting that part of the NOX reduction was proceeding through an ammonium nitrate intermediate and generating nitric acid. In addition, NH3 oxidation into N2O was prevalent at 300°C in an excess of NO2. The SCR reaction results indicate that both transient effects and side reactions play an important role in an NH3 SCR system, particularly one that is designed to operate under continuously changing conditions.Catalyst aging mechanisms were investigated by comparing catalytic performance, material structure, and surface composition of a new and a used zeolite catalyst monolith for the fast SCR reaction. Physical analysis of the catalyst monoliths through X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) with Energy-Dispersive X-ray Spectroscopy (EDS) indicated four aging mechanisms. Both the new and used catalyst monoliths performed at least 95% NOX reduction in the fast reaction at all temperatures tested. Despite the similar NOX reduction performance, the used catalyst monolith exhibited lower NO oxidation performance, increased NH3 oxidation, and a lower quantity of adsorbed NH3 compared to the new catalyst monolith. Dealumination is likely the primary cause of the used catalyst monolith's lower NOX reduction performance with promoter metal deactivation, poisoning by sulfur and phosphorous, and mechanical failure of the catalyst coating on the monolith also contributing to the decreased performance. The results do not find evidence of carbon coking. This investigation into catalyst aging mechanisms confirms the efficacy of the commercial SCR catalyst monolith over long time periods.
Book Synopsis Selective Catalytic Reduction of NOx by : Oliver Kröcher
Download or read book Selective Catalytic Reduction of NOx written by Oliver Kröcher and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The most efficient process to reduce NOx emissions from lean exhaust gases, selective catalytic reduction (SCR) with ammonia, has undergone tremendous development over the past decades. Originally only applied in stationary power plants and industrial installations, SCR systems are now installed in millions of mobile diesel engines, ranging from off-road machineries, to heavy-duty and light-duty trucks and passenger cars, to locomotives and ships. All of these applications involve specific challenges due to tighter emission limits, new internal combustion engine technologies, or alternative fuels. Three review articles and 14 research articles in this book describe recent results and research trends of various aspects of the SCR process. Reaction engineering aspects, such as the proper dosage of ammonia or urea, respectively, are as important as further developments of the different SCR catalysts, by deepening the understanding of their functionality or by systematic improvements of their properties, such as low-temperature activity, selectivity, or poisoning-resistance. Another covered aspect is cost reduction through the use of cheaper base materials for the production is active and stable SCR catalysts. Finally, research efforts are reported to develop SCR processes with different reducing agents, which would open doors to new applications in the future. The range of topics addressed in this book will stimulate the reader's interest as well as provide a valuable source of information for researchers in academia and industry.
Book Synopsis Selective Catalytic Reduction of NOx by NH3 (NH3-SCR) in Small Pore Cu-exchanged Chabazite (CHA) Catalysts by : Di Wang
Download or read book Selective Catalytic Reduction of NOx by NH3 (NH3-SCR) in Small Pore Cu-exchanged Chabazite (CHA) Catalysts written by Di Wang and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitrogen oxides, NOx (NO+NO2), are considered significant air pollutants. Selective catalytic reduction of NOx with NH3 (NH3-SCR) is a leading technology candidate for NOx emissions control for diesel engine vehicles. Recently, the Cu-exchanged chabazite framework type zeolite with small pores, such as SAPO-34 and SSZ-13, has received a great deal of attention due to exceptional hydrothermal durability and enhanced SCR activity. I have carried out a systematic study over both Cu-SAPO-34 and Cu-SSZ-13 catalysts to elucidate the reaction mechanisms, acid properties, Cu structures, active centers and deactivation modes. First, the intrinsic mechanism of the SCR reaction over a Cu-exchanged SAPO-34 catalyst at low temperature was studied by in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), coupled with a mass spectrometer to measure inlet and outlet gas concentrations. The evolution of the surface intermediates, as well as the reactivity of NH3 with surface NOx species and NOx with surface NH3 species, was evaluated. Second, a series of SAPO-34 catalysts with various Cu loadings (ranging 0.7-3.0 wt%) was prepared by a solid state ion exchange method (SSIE). The acid properties as well as the Cu structures were characterized by XRD, NH3-TPD, UV-vis, DRIFTS and H2-TPR. Third, a SSIE method was developed to synthesize Cu-SSZ-13 catalysts with excellent NH3-SCR performance and durable hydrothermal stability. After the SSIE process, the SSZ framework structure and surface area was maintained. DRIFTS and NH3-TPD experiments provide evidence that Cu ions were successfully exchanged with Brønsted acid protons in the pores. Fourth, the hydrothermal stability of Cu-SAPO-34 and Cu-SSZ-13 was studied. Their different evolutions of zeolite framework, acidity and Cu structure during the hydrothermal aging were probed by XRD, DRIFTS and NH3-TPD. The results suggest that Cu-SAPO-34 is more resistant to hydrothermal aging in comparison to Cu-SSZ-13. Last, the SO2 poisoning effect over Cu-SAPO-34 catalyst was investigated by using in-situ DRIFTS combined with temperature programmed desorption (TPD) experiments. It was found that the low temperature deactivation mechanism involved the formation of ammonium sulfate species as well as the competitive adsorption SO2 with NOx.
Book Synopsis Modeling of Selective Catalytic Reduction (SCR) of Nitric Oxide with Ammonia Using Four Modern Catalysts by : Giriraj Sharma
Download or read book Modeling of Selective Catalytic Reduction (SCR) of Nitric Oxide with Ammonia Using Four Modern Catalysts written by Giriraj Sharma and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work, the steady-state performance of zeolite-based Cu-ZSM-5, vanadium based honeycomb monolith catalysts (V), vanadium-titanium based pillared inter layered clay catalyst (V-Ti PLIC) and vanadium-titanium-tungsten-based honeycomb monolith catalysts (V-Ti-W) was investigated in the selective catalytic reduction process (SCR) for NO removal using NH3 in presence of oxygen. The objective is to obtain the expression that would predict the conversion performance of the catalysts for different values of the SCR process parameters, namely temperature, inlet oxygen concentration and inlet ammonia concentration. The NO[subscript]x emission, its formation and control methods are discussed briefly and then the fundamentals of the SCR process are described. Heat transfer based and chemical kinetics based SCR process models are discussed and widely used rate order based model are reviewed. Based on the experimental data, regression analysis was performed that gives an expression for predicting the SCR rate for the complete temperature range and the rate order with respect to inlet oxygen and ammonia concentration. The average activation energy for the SCR process was calculated and optimum operating conditions were determined for each of the catalyst. The applicable operating range for the catalyst depends on the NO conversion as well as on the ammonia slip and the N2O and NO2 emission. The regression analysis was repeated for the applicable range and an expression was obtained that can be used to estimate the catalyst performance. For the Cu-ZSM-5, the best performance was observed for 400°C, 660 ppm inlet ammonia concentration and 0.1% inlet oxygen concentration. For the V based honeycomb monolith catalyst, the best performance was observed for 300°C, 264 ppm inlet ammonia concentration and 3% inlet oxygen concentration. For the V-Ti based PLIC catalyst, the best performance was observed for 350°C, 330 ppm inlet ammonia concentration and 3% inlet oxygen concentration. For the V-Ti-W based honeycomb monolith catalyst, the best performance was observed for 300°C, 330 ppm inlet ammonia concentration and 3% inlet oxygen concentration. The conversion performance of all of these catalysts is satisfactory for the industrial application. At the operating conditions listed above, the N2O emission is less than 20 ppm and the NO2 emission is less than 10 ppm. The results were validated by comparing the findings with the similar work by other research groups. The mechanism of SCR process is discussed for each of the catalyst. The probable reactions are listed and adsorption and desorption process are studied. The various mechanisms proposed by the researchers are discussed briefly. It is concluded that V-Ti-W and Cu-ZSM-5 catalyst are very promising for SCR of NO[subscript]x. The expressions can be used to estimate the conversion performance and can be utilized for optimal design and operation. The expressions relate the SCR rate to the input parameters such as temperature and inlet oxygen and ammonia concentration hence by controlling these parameters desired NO[subscript]x reduction can be achieved with minimal cost and emission.
Book Synopsis A Systematic Approach for Performance Comparisons of NOx Converter Designs by : Michelle Bendrich
Download or read book A Systematic Approach for Performance Comparisons of NOx Converter Designs written by Michelle Bendrich and published by . This book was released on 2014 with total page 83 pages. Available in PDF, EPUB and Kindle. Book excerpt: In today's vehicle applications, Selective Catalytic Reduction (SCR) ammonia dosing is completed using complex control algorithms that need to be parameterized for the individual catalytic converter technology. The parameterization of these control strategies is not always completed during the early design phase (i.e., simulation studies and laboratory tests), as this procedure is very time consuming. This results in catalytic converter screenings being completed with dosing strategies that do not allow for the observation of the true potential of each catalytic converter. Therefore, a challenge arises in the effective design of catalytic converters. This work presents a simulation-based method for the automated optimization of a simple ammonia dosing strategy, which can easily be used for simulations during the early catalytic converter design phase. The dosing strategy relies on a look-up table whose entries relate a desired ammonia surface coverage to a catalyst temperature. These entries are optimized for a given driving cycle to maximize the NOx conversion and fulfill the desired ammonia slip constraints. Using this strategy, comparisons of SCR catalyst technologies (iron and copper zeolite SCR) and catalyst volumes during driving cycles are completed. Likewise, the dosing strategy is applied to a catalytic converter configuration consisting of a front-end SCR and a back-end Ammonia Slip Catalyst (ASC) to study how an ASC can assist in meeting regulatory requirements during driving cycles.
Book Synopsis Passive Ammonia-SCR Catalyst System for NOx Abatement from Lean-burn Gasoline Engines by : Vitaly Y. Prikhodko
Download or read book Passive Ammonia-SCR Catalyst System for NOx Abatement from Lean-burn Gasoline Engines written by Vitaly Y. Prikhodko and published by . This book was released on 2018 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation summarizes experimental and computational observations from investigations of a selective catalytic reduction (SCR) system for reducing nitrogen oxides (NOx) in lean gasoline engine exhaust based on utilizing ammonia (NH3) generated by a three-way catalyst (TWC) during brief periods of fuel-rich engine operation. NH3 released from the TWC is stored and available to reduce NOx on a downstream SCR catalyst during subsequent periods of lean engine operation. The experimental results include high-speed measurements of transient NH3 formation on the TWC monolith catalysts, as the catalysts were exposed to lean gasoline engine exhaust from a commercial engine. In addition to the experimental investigations, dynamic computational simulations of NH3 generation on the TWC catalyst were implemented to provide more detailed information about NH3 generation on TWCs based on available reaction kinetic mechanisms. Based on the experimental and computational results, estimates of the potential fuel efficiency gains and emissions relevant to simulated drive cycles indicate that passive SCR can potentially achieve significant fuel efficiency benefits while still meeting regulated NOx emissions limits for vehicles powered by lean gasoline engines. However, optimal performance of the system will most likely require development of emission control methods that include accurate models for SCR catalyst NH3 storage and reaction under realistic drive-cycle transients.
Book Synopsis Modeling and Analysis of Performance on a Field-aged Fe-zeolite Catalyst by : Roxanna Moores
Download or read book Modeling and Analysis of Performance on a Field-aged Fe-zeolite Catalyst written by Roxanna Moores and published by . This book was released on 2014 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study a 1-dimensional computational model implementing conservation of mass, species and energy for both the gas phase and catalyst surface has been developed to predict the performance of an Fe-Zeolite selective catalytic reduction catalyst. This work investigates and analyzes the behavior of a fresh Fe-Zeolite catalyst as well as one that has been aged in a Heavy Duty Diesel engine performing in the field for 376k miles. The chemistry and performance for the two Fe-Zeolite configurations for the NH3 Storage, NH3 oxidation, NO Oxidation, Standard, Slow and Fast reactions are correlated and examined against synthetic gas rig test bench data and then subsequently verified with engine laboratory testing. It has been found that the Standard reaction was the most degraded reaction and the Fast reaction was the least affected by aging. As a result, in order to have the field-aged catalyst functioning to its optimized activity, the Fast reaction needs to be activated by keeping the NOx gas feed with a 50 % NO and 50 % NO2 gas composition.
Book Synopsis Calibration and Performance of a Selective Catalytic Reduction (SCR) Bench Rig for NOx̳ Emissions Control by : Castro Galnares Wright Paz Castro Galnares
Download or read book Calibration and Performance of a Selective Catalytic Reduction (SCR) Bench Rig for NOx̳ Emissions Control written by Castro Galnares Wright Paz Castro Galnares and published by . This book was released on 2008 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: A laboratory test rig was designed and built to easily test SCR (Selective Catalytic Reduction) technology. Equipped with three 6 kW heaters, connections for liquid N2 and an assortment of test gases, and a connection with an MKS NOx Analyzer, the rig allows for a vast range of SCR test conditions, and can easily be adapted for degreening, aging, and the implementation of other technologies onto the rig. To calibrate the test rig, baseline parameterization of a Cu-based zeolite (aluminosilicate) core was performed, including a temperature sweep and an NO/NO2 concentration sweep, while always maintaining a 1:1 ratio between NOx and NH3 reductant. The catalyst was found to have a peak deNOx efficiency of 99.8% between 250 'C and 300 'C, and maintained 98% efficiency with NO/NO2
Book Synopsis Development of Zeolite Catalysts for NOx Reduction with NH3 in Diesel Exhaust Gas by : Eri Ito
Download or read book Development of Zeolite Catalysts for NOx Reduction with NH3 in Diesel Exhaust Gas written by Eri Ito and published by . This book was released on 1996 with total page 223 pages. Available in PDF, EPUB and Kindle. Book excerpt:
