scholarly journals Deactivation of a Vanadium-Based SCR Catalyst Used in a Biogas-Powered Euro VI Heavy-Duty Engine Installation

Catalysts ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 552
Author(s):  
Johanna Englund ◽  
Sandra Dahlin ◽  
Andreas Schaefer ◽  
Kunpeng Xie ◽  
Lennart Andersson ◽  
...  
Keyword(s):  
Active Sites ◽  
Catalytic Reduction ◽  
Nox Reduction ◽  
Oxidation Catalyst ◽  
Particulate Filter ◽  
Heavy Duty ◽  
Scr Catalyst ◽  
Before And After ◽  
Emission Control System ◽  
Catalyst Poisons

We have investigated how the exhaust gases from a heavy-duty Euro VI engine, powered with biogas impact a vanadium-based selective catalytic reduction (SCR) catalyst in terms of performance. A full Euro VI emission control system was used and the accumulation of catalyst poisons from the combustion was investigated for the up-stream particulate filter as well as the SCR catalyst. The NOx reduction performance in terms of standard, fast and NO2-rich SCR was evaluated before and after exposure to exhaust from a biogas-powered engine for 900 h. The SCR catalyst retains a significant part of its activity towards NOx reduction after exposure to biogas exhaust, likely due to capture of catalyst poisons on the up-stream components where the deactivation of the oxidation catalyst is especially profound. At lower temperatures some deactivation of the first part of the SCR catalyst was observed which could be explained by a considerably higher surface V4+/V5+ ratio for this sample compared to the other samples. The higher value indicates that the reoxidation of V4+ to V5+ is partially hindered, blocking the redox cycle for parts of the active sites.

scholarly journals Deactivation of a Pd/Pt Bimetallic Oxidation Catalyst Used in a Biogas-Powered Euro VI Heavy-Duty Engine Installation

Catalysts ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1014 ◽  
Author(s):  
Johanna Englund ◽  
Kunpeng Xie ◽  
Sandra Dahlin ◽  
Andreas Schaefer ◽  
Dazheng Jing ◽  
...  
Keyword(s):  
Methane Oxidation ◽  
Active Sites ◽  
Oxidation Catalyst ◽  
Heavy Duty ◽  
Synthetic Gas ◽  
Before And After ◽  
Activity Loss ◽  
Catalyst Poisons ◽  
Oxidation Of No ◽  
Bimetallic Palladium

The reduction of anthropogenic greenhouse gas emissions is crucial to avoid further warming of the planet. We investigated how effluent gases from a biogas powered Euro VI heavy-duty engine impact the performance of a bimetallic (palladium and platinum) oxidation catalyst. Using synthetic gas mixtures, the oxidation of NO, CO, and CH4 before and after exposure to biogas exhaust for 900 h was studied. The catalyst lost most of its activity for methane oxidation, and the activity loss was most severe for the inlet part of the aged catalyst. Here, a clear sintering of Pt and Pd was observed, and higher concentrations of catalyst poisons such as sulfur and phosphorus were detected. The sintering and poisoning resulted in less available active sites and hence lower activity for methane oxidation.

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.

scholarly journals Investigation of Urea Uniformity with Different Types of Urea Injectors in an SCR System

Catalysts ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1269
Author(s):  
Muhammad Khristamto Aditya Wardana ◽  
Kwangchul Oh ◽  
Ocktaeck Lim
Keyword(s):  
Diesel Engine ◽  
Catalytic Reduction ◽  
Nox Reduction ◽  
Heavy Duty ◽  
Ammonia Gas ◽  
Experimental Parameters ◽  
Heavy Duty Diesel Engine ◽  
Heavy Duty Diesel ◽  
Scr System

Heavy-duty diesel engines in highway use account for more than 40% of total particulate and nitrogen oxide (NOx) emissions around the world. Selective catalytic reduction (SCR) is a method with effective results to reduce this problem. This research deals with problems in the urea evaporation process and ammonia gas distribution in an SCR system. The studied system used two types of urea injectors to elucidate the quality of ammonia uniformity in the SCR system, and a 12,000-cc heavy-duty diesel engine was used for experimentation to reduce NOx in the system. The uniformity of the generated quantities of ammonia was sampled at the catalyst inlet using a gas sensor. The ammonia samples from the two types of urea injectors were compared in experimental and simulation results, where the simulation conditions were based on experimental parameters and were performed using the commercial CFD (computational fluid dynamics) code of STAR-CCM+. This study produces temperatures of 371 to 374 °C to assist the vaporization phenomena of two injectors, the gas pattern informs the distributions of ammonia in the system, and the high ammonia quantity from the I-type urea injector and high quality of ammonia uniformity from the L-type urea injector can produce different results for NOx reduction efficiency quality after the catalyst process. The investigations showed the performance of two types of injectors and catalysts in the SCR system in a heavy-duty diesel engine.

Development of an Open Loop Fuzzy Logic Urea Dosage Controller for Use With an SCR Equipped HDD Engine

2009 ◽  
Author(s):  
Raffaello Ardanese ◽  
Michelangelo Ardanese ◽  
Marc C. Besch ◽  
Theodore Adams ◽  
Arvind Thiruvengadam ◽  
...  
Keyword(s):  
Fuzzy Logic ◽  
Catalytic Reduction ◽  
Control Strategies ◽  
Open Loop ◽  
Particulate Filter ◽  
Oxides Of Nitrogen ◽  
Heavy Duty ◽  
Ammonia Slip ◽  
Fuzzy Logic Approach ◽  
Heavy Duty Diesel

Selective Catalytic Reduction (SCR) systems have been shown to be the most promising exhaust aftertreatment system for near term in-use applications to meet the stringent US 2010 oxides of nitrogen (NOx) emissions regulations of 0.2 g/bhp-hr for on-highway heavy duty diesel engines. SCR systems use the ammonia-containing compound urea, as a reducing agent. In order to control the urea dosage during transient operation of the engine, sophisticated control strategies are needed. This study discusses the development of an open loop, non-sensor based fuzzy logic urea dosage controller. The goal of the fuzzy logic based control was to achieve maximum NOx emission reduction, while limiting the amount of ammonia slip. The open loop controller was implemented on a heavy duty diesel engine equipped with a catalyzed diesel particulate filter (DPF) and a SCR system. The control system was quantified by operating the engine over different test cycles on an engine dynamometer. This study shows that the fuzzy logic approach is a simple and effective way to control NOx, as well as ammonia slip.

scholarly journals Direct Simultaneous Measurement of Particulate Matter and Ammonia Storage on Combined Selective Catalytic Reduction Filter Systems Using Radio Frequency Sensors

2018 ◽  
Author(s):  
Paul A. Ragaller ◽  
Alexander Sappok ◽  
Jie Qiao ◽  
Xiaojin Liu ◽  
Jonathan Aguilar
Keyword(s):  
Particulate Matter ◽  
Radio Frequency ◽  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Nox Reduction ◽  
Particulate Filter ◽  
Practical Implementation ◽  
Simultaneous Measurements ◽  
Soot Loading ◽  
Rf Spectrum

Tightening global emissions regulations are motivating interest in the development and implementation of Selective Catalytic Reduction + Filtration (SCRF) systems, which are designed to reduce the concentration of tailpipe particulate matter (PM) and NOx emissions. These systems allow designers to combine the NOx reduction capability of an SCR with the filtration capability of a particulate filter on a single unit. Practical implementation of these systems requires reliable measurement and diagnosis of their state — both with respect to trapped particulate matter as well as adsorbed ammonia. Currently, these systems rely on a variety of gas sensors, mounted upstream or downstream of the system, that only provide an indirect inference of the operation state. In this study, a single radio frequency (RF) sensor was used to perform simultaneous measurements of soot loading and ammonia inventory on an SCRF. Several SCRF core samples were tested at varying soot and ash loads in a catalyst reactor bench. Soot levels were measured by monitoring changes in the bulk dielectric properties within the catalyst using the sensor, while ammonia levels were determined by feeding selected regions of the RF spectrum into a pretrained generalized regression neural network model. Results show the RF sensor is able to directly measure the instantaneous ammonia inventory, while simultaneously providing soot loading measurements within 0.5 g/L. These results confirm that simultaneous measurements of both the PM and ammonia loading state of an SCRF are possible using a single RF sensor via analysis of specific features in the full RF spectrum. The results indicate significant potential to remove the control barriers typically associated with the implementation of advanced SCRF systems.

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.

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