Selective catalytic reduction: Adding an ammonia slip catalyst mitigates dosing errors

2021 ◽  
Author(s):  
Michelle Bendrich ◽  
Bastian Opitz ◽  
Alexander Scheuer ◽  
Robert E. Hayes ◽  
Martin Votsmeier
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Ammonia Slip

Coordinated Active Thermal Management and Selective Catalytic Reduction Control for Simultaneous Fuel Economy Improvement and Emissions Reduction During Low-Temperature Operations

2015 ◽  
Vol 137 (12) ◽  
Author(s):  
Pingen Chen ◽  
Junmin Wang
Keyword(s):  
Low Temperature ◽  
Selective Catalytic Reduction ◽  
Thermal Management ◽  
Catalytic Reduction ◽  
Coordinated Control ◽  
Nox Emissions ◽  
Total Cost ◽  
Nox Conversion ◽  
Ammonia Slip ◽  
Nox Conversion Efficiency

The low-temperature operations of diesel engines and aftertreatment systems have attracted increasing attention over the past decade due to the stringent diesel emission regulations and excessive tailpipe emissions at low temperatures. The removal of NOx emissions using selective catalytic reduction (SCR) systems during low-temperature operations remains a significant challenge. One of the popular techniques for alleviating this issue is to employ active thermal management via in-cylinder postinjection to promote aftertreatment system temperatures. Meanwhile, numerous studies have focused on ammonia coverage ratio controls with the aim to maintain high NOx conversion efficiency and low tailpipe ammonia slip. However, most of the active thermal management and SCR controls in the existing literatures were separately and conservatively designed, which can lead to higher cost of SCR operation than needed including diesel fuel consumption through active thermal management and urea solution consumption. The main purpose of this study is to design and coordinate active thermal management and SCR control using nonlinear model predictive control (NMPC) approach to minimize the total cost of SCR operation while obtaining high NOx conversion efficiency and low tailpipe ammonia slip. Simulation results demonstrate that, compared to the baseline control which consists of separated active thermal management and SCR control, the coordinated control is capable of reducing the total cost of SCR operation by 25.6% while maintaining the tailpipe NOx emissions and ammonia slip at comparable levels. Such an innovative coordinated control design concept shows its promise in achieving low tailpipe emissions during low-temperature operations in a cost-effective fashion.

Modeling and analysis of transport and reaction in washcoated monoliths: Cu-SSZ-13 SCR and dual-layer Cu-SSZ-13 + Pt/Al2O3 ASC

2019 ◽  
Vol 4 (6) ◽  
pp. 1103-1115 ◽  
Author(s):  
Pritpal S. Dhillon ◽  
Michael P. Harold ◽  
Di Wang ◽  
Ashok Kumar ◽  
Saurabh Y. Joshi
Keyword(s):  
Selective Catalytic Reduction ◽  
Ammonia Oxidation ◽  
Catalytic Reduction ◽  
Modeling And Analysis ◽  
Ammonia Slip ◽  
Monolith Catalysts

Modeling and analysis of washcoated single- and dual-layer monolith catalysts is presented for selective catalytic reduction (SCR) on Cu-SSZ-13 and ammonia oxidation on Cu-SSZ-13 + Pt/Al2O3 ammonia slip catalyst (ASC).

It is no laughing matter: nitrous oxide formation in diesel engines and advances in its abatement over rhodium-based catalysts

2016 ◽  
Vol 6 (21) ◽  
pp. 7671-7687 ◽  
Author(s):  
Magdalena Jabłońska ◽  
Regina Palkovits
Keyword(s):  
Nitrous Oxide ◽  
Diesel Engine ◽  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Oxide Formation ◽  
Diesel Oxidation Catalysts ◽  
Diesel Oxidation ◽  
Ammonia Slip ◽  
Aftertreatment Systems ◽  
By Products

N2O appears as one of the undesired by-products in exhaust gases emitted from diesel engine aftertreatment systems, such as diesel oxidation catalysts (DOC), lean NOx trap (LNT, also known as NOx storage and reduction (NSR)) or selective catalytic reduction (NH3-SCR and HC-SCR) and ammonia slip catalysts (ASC, AMOX, guard catalyst).

Urea injection control strategy in urea-selective catalytic reduction for heavy-duty diesel engine under transient process

2019 ◽  
pp. 146808741986063
Author(s):  
Binyang Wu ◽  
Longfei Deng ◽  
Yize Liu ◽  
Dezeng Sun ◽  
Wanhua Su
Keyword(s):  
Selective Catalytic Reduction ◽  
Transient Process ◽  
Catalytic Reduction ◽  
Heavy Duty ◽  
Ammonia Slip ◽  
Ammonia Storage ◽  
Heavy Duty Diesel Engine ◽  
Injection Control ◽  
Storage Area ◽  
Heavy Duty Diesel

A urea injection control strategy for urea-selective catalytic reduction under a transient process is investigated on a heavy-duty diesel engine test bench in this study. The aim is to improve NO x conversion efficiency and reduce ammonia slip. With the selective catalytic reduction system as the research object, an open thermodynamic conservation system is established. The conservation relationship in the process of urea injection, NO x reduction reaction, ammonia storage, and ammonia slip is investigated. The ideal target ammonia storage area and the ammonia storage characteristics during the transient process are studied. The ammonia storage area and boundary, which change with the transient temperature, are established. Correction of real-time ammonia injection is further deduced from the boundary of the area. The world harmonized transient cycle test cycle result showed that compared to feed-forward control, the NO x conversion efficiency increased by 16% and the NH3 slip decreased by 75% when using the proposed real-time ammonia storage-management control method.

Sliding-mode control of automotive selective catalytic reduction systems with state estimation

2019 ◽  
Vol 234 (2-3) ◽  
pp. 630-644
Author(s):  
Yao Ma ◽  
Junmin Wang
Keyword(s):  
Selective Catalytic Reduction ◽  
Surface Coverage ◽  
Sliding Mode ◽  
Catalytic Reduction ◽  
Tracking Error ◽  
Estimation Accuracy ◽  
Sliding Mode Controller ◽  
Coverage Ratio ◽  
Implementation Purpose ◽  
Ammonia Slip

A sliding-mode controller for an automotive selective catalytic reduction system is designed to drive its ammonia surface coverage ratio to the target level. The proposed controller only requires NOx, temperature and air flow sensor measurement installed on most mass production vehicles. Selective catalytic reduction systems have been widely equipped on diesel-powered ground vehicles to remove excessive NOx emissions. The tradeoff between NOx removal efficiency and ammonia slip poses a control challenge on regulating the ammonia surface coverage ratio to a proper level in the presence of disturbance. In this study, a sliding-mode controller is designed with explicit consideration of measurement noise and actuator saturation. The finite time convergence of tracking error is proved by a Lyapunov approach. For implementation purpose, an observer of ammonia surface coverage ratio and ammonia slip is also designed to provide states feedback and fault diagnostic information. The closed-loop controller performance is evaluated under an urban driving scenario based on an experimentally validated model. Results demonstrate the robust tracking performance and estimation accuracy against bounded uncertainties. The overall NOx efficiency is maintained with an acceptable ammonia slip level during the transient test cycle FTP75.

Highly dispersed MnOx–FeOx supported by silicalite-1 for the selective catalytic reduction of NOx with NH3 at low temperatures

2020 ◽  
Vol 10 (16) ◽  
pp. 5525-5534 ◽  
Author(s):  
Jialiang Gu ◽  
Bingjun Zhu ◽  
Rudi Duan ◽  
Yan Chen ◽  
Shaoxin Wang ◽  
...  
Keyword(s):  
Selective Catalytic Reduction ◽  
Low Temperatures ◽  
Catalytic Reduction ◽  
Highly Dispersed ◽  
Reduction Of Nox

MnOx–FeOx-Loaded silicalite-1 catalysts exhibit high NOx conversion at low temperatures.

Transition-metal-free catalytic hydroboration reduction of amides to amines

2020 ◽  
Vol 7 (21) ◽  
pp. 3515-3520
Author(s):  
Wubing Yao ◽  
Jiali Wang ◽  
Aiguo Zhong ◽  
Shiliang Wang ◽  
Yinlin Shao
Keyword(s):  
Transition Metal ◽  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Value Added ◽  
Metal Free

The selective catalytic reduction of amides to value-added amine products is a desirable but challenging transformation.

Comparative analysis on the effects of diesel particulate filter and selective catalytic reduction systems on a wide spectrum of chemical species emissions

2018 ◽  
Author(s):  
Z. Gerald Liu ◽  
Devin R. Berg ◽  
Thaddeus A. Swor ◽  
James J. Schauer‡
Keyword(s):  
Diesel Engine ◽  
Selective Catalytic Reduction ◽  
Diesel Particulate Filter ◽  
Catalytic Reduction ◽  
Wide Spectrum ◽  
Chemical Species ◽  
Pollutant Emissions ◽  
Particulate Filter ◽  
Diesel Particulate ◽  
Aftertreatment Systems

Two methods, diesel particulate filter (DPF) and selective catalytic reduction (SCR) systems, for controlling diesel emissions have become widely used, either independently or together, for meeting increasingly stringent emissions regulations world-wide. Each of these systems is designed for the reduction of primary pollutant emissions including particulate matter (PM) for the DPF and nitrogen oxides (NOx) for the SCR. However, there have been growing concerns regarding the secondary reactions that these aftertreatment systems may promote involving unregulated species emissions. This study was performed to gain an understanding of the effects that these aftertreatment systems may have on the emission levels of a wide spectrum of chemical species found in diesel engine exhaust. Samples were extracted using a source dilution sampling system designed to collect exhaust samples representative of real-world emissions. Testing was conducted on a heavy-duty diesel engine with no aftertreatment devices to establish a baseline measurement and also on the same engine equipped first with a DPF system and then a SCR system. Each of the samples was analyzed for a wide variety of chemical species, including elemental and organic carbon, metals, ions, n-alkanes, aldehydes, and polycyclic aromatic hydrocarbons, in addition to the primary pollutants, due to the potential risks they pose to the environment and public health. The results show that the DPF and SCR systems were capable of substantially reducing PM and NOx emissions, respectively. Further, each of the systems significantly reduced the emission levels of the unregulated chemical species, while the notable formation of new chemical species was not observed. It is expected that a combination of the two systems in some future engine applications would reduce both primary and secondary emissions significantly.

Effect of Fe on the Selective Catalytic Reduction of NO by NH3 at Low Temperature over Mn/CeO2-TiO2 Catalyst

2012 ◽  
Vol 27 (5) ◽  
pp. 495-500 ◽  
Author(s):  
Da-Wang WU ◽  
Qiu-Lin ZHANG ◽  
Tao LIN ◽  
Mao-Chu GONG ◽  
Yao-Qiang CHEN
Keyword(s):  
Low Temperature ◽  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Reduction Of No
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