scholarly journals Experimental and kinetic modeling study for N2O formation of NH3-SCR over commercial Cu-zeolite catalyst

2021 ◽  
Vol 13 (4) ◽  
pp. 168781402110106
Author(s):  
Songfeng Li ◽  
Chunhua Zhang ◽  
Ao Zhou ◽  
Yangyang Li ◽  
Peng Yin ◽  
...  
Keyword(s):  
Kinetic Model ◽  
Flow Reactor ◽  
Catalytic Reduction ◽  
Current Model ◽  
Ammonia Nitrogen ◽  
No Oxidation ◽  
Reactor Outlet ◽  
N2o Formation ◽  
Scr System ◽  
Denox Efficiency

In this paper, a systematic experimental and kinetic model investigation was conducted over Cu-SSZ-13 catalyst to study the DeNOx efficiency and N2O formation for selective catalytic reduction of NOx with NH3 (NH3-SCR). The kinetic model was developed for various reactions to take place in the NH3-SCR system, including NH3 adsorption/desorption, NH3 oxidation, NO oxidation, standard SCR, fast SCR, slow SCR and N2O formation reactions. In addition, the reaction of N2O formation from NH3 non-selective oxidation was taken into account. All the experiments were performed in a flow reactor with a feed stream near to the real application of diesel engine vehicles exhaust. The current model can satisfactorily predict the steady state conversion rate of various species at the reactor outlet and the effect of gas hourly space velocities and ammonia nitrogen ratio on N2O formation. The results show that the kinetic model can simulate the reaction process of the Cu-SSZ-13 catalyst well. This is significant for the optimization of NH3-SCR system for achieving the higher DeNOx efficiency and the lower N2O emission.

scholarly journals Numerical Simulation of O3 and NO Reacting in a Tubular Flow Reactor

2013 ◽  
Vol 34 (3) ◽  
pp. 361-373 ◽  
Author(s):  
Norbert J. Modliński ◽  
Włodzimierz K. Kordylewski ◽  
Maciej P. Jakubiak
Keyword(s):  
Reaction Mechanism ◽  
Flow Reactor ◽  
Catalytic Reduction ◽  
Model Performance ◽  
Flow Simulation ◽  
No Oxidation ◽  
Reacting Flow ◽  
Reactor Outlet ◽  
Tubular Flow Reactor ◽  
Tubular Flow

Abstract A process capable of NOx control by ozone injection gained wide attention as a possible alternative to proven post combustion technologies such as selective catalytic (and non-catalytic) reduction. The purpose of the work was to develop a numerical model of NO oxidation with O3 that would be capable of providing guidelines for process optimisation during different design stages. A Computational Fluid Dynamics code was used to simulate turbulent reacting flow. In order to reduce computation expense a 11-step global NO - O3 reaction mechanism was implemented into the code. Model performance was verified by the experiment in a tubular flow reactor for two injection nozzle configurations and for two O3/NO ratios of molar fluxe. The objective of this work was to estimate the applicability of a simplified homogeneous reaction mechanism in reactive turbulent flow simulation. Quantitative conformity was not completely satisfying for all examined cases, but the final effect of NO oxidation was predicted correctly at the reactor outlet.

scholarly journals Insight into Platinum Poisoning Effect on Cu-SSZ-13 in Selective Catalytic Reduction of NOx with NH3

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 796
Author(s):  
Huawang Zhao ◽  
Lei Han ◽  
Yujie Wang ◽  
Jiandong Zheng
Keyword(s):  
Catalytic Reduction ◽  
No Oxidation ◽  
Oxidation Reactions ◽  
Hydrothermal Aging ◽  
N2o Formation ◽  
Poisoning Effect ◽  
Nh3 Oxidation ◽  
Reduction Of Nox ◽  
Parallel Reactions ◽  
Insight Into

Platinum’s (Pt) poisoning effect on Cu-SSZ-13 and its regeneration were investigated. The Pt enhanced the parallel reactions, such as NH3 oxidation and NO oxidation reactions, which decreased the deNOx activities. In the temperature range below 330 °C, the deactivation of Cu-SSZ-13 by Pt poisoning was primarily caused by the overconsumption of NH3, due to the enhanced NH3-selective oxidation reaction, while the formation of NOx in NH3 oxidation and NO oxidation into NO2 further aggravated the degradation when the temperature was above 460 °C. The non-selective NH3 oxidation and non-selective NOx catalytic reduction reactions resulted in increased N2O formation over Pt-doped samples. The transformation of Pt0 into PtOx after hydrothermal aging recovered the deNOx activities of the Pt-poisoned samples.

scholarly journals Experimental and Modeling Study of CO-Selective Catalytic Reduction of NO Over Perovskite-Type Nanocatalysts

2019 ◽  
Vol 64 (1) ◽  
pp. 46-53 ◽  
Author(s):  
Shiva Abedi ◽  
Aligholi Niaei ◽  
Najaf Namjou ◽  
Darioush Salari ◽  
Ali Tarjomannejad ◽  
...  
Keyword(s):  
Kinetic Model ◽  
Selective Catalytic Reduction ◽  
Flow Reactor ◽  
Catalytic Reduction ◽  
Sol Gel ◽  
Plug Flow ◽  
Correlation Coefficients ◽  
Reduction Of No ◽  
Proposed Model ◽  
Perovskite Type

In this work LaFeO3, LaFe0.7Mn0.3O3 and LaMn0.7Fe0.3O3 nanocatalysts with perovskite structures have been synthesized by sol-gel method. The selective catalytic reduction of NO with CO (CO-SCR) using synthesized nanocatalysts was investigated in a plug flow reactor. The kinetics of CO-SCR process was studied and three kinetic models were used to describe the behavior of the system, including power low model (PLM), kinetic model 1 (KM1) and kinetic model 2 (KM2). The KM1 was the best model with correlation coefficients of 0.9924, 0.9911 and 0.9902 and the sum of squared errors of 0.0504, 0.0488 and 0.0397, for LaFeO3, LaFe0.7Mn0.3O3 and LaFe0.3Mn0.7O3 catalysts, respectively. By comparing experimental results with the predicted results of the KM1, it was found that the proposed model can predict the performance of catalysts in the CO-SCR process with considerable precision. The structure and morphology of perovskite-type oxides were characterized by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively.

Mechanistic insight into the influence of O2 on N2O formation in the selective catalytic reduction of NO with NH3 over Pd/CeO2 catalyst

2021 ◽  
Author(s):  
Liping Sheng ◽  
Songda Li ◽  
Zhaoxia Ma ◽  
Fei Wang ◽  
Hu He ◽  
...  
Keyword(s):  
Selective Catalytic Reduction ◽  
No Reduction ◽  
Catalytic Reduction ◽  
Temperature Dependent ◽  
N2o Formation ◽  
Reduction Of No ◽  
Mechanistic Insight ◽  
Insight Into

O2 greatly affected the pathway for NO reduction over the Pd/CeO2 catalyst and resulted in a temperature-dependent NH3-SCR performance and formation of N2O.

Ignition Characteristics of a Fischer-Tropsch Synthetic Jet Fuel

2008 ◽  
Author(s):  
P. Gokulakrishnan ◽  
M. S. Klassen ◽  
R. J. Roby
Keyword(s):  
Kinetic Model ◽  
Ignition Delay ◽  
Flow Reactor ◽  
Kinetic Mechanism ◽  
Jet Fuel ◽  
Synthetic Jet ◽  
Jet Fuels ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Ignition Characteristics

Ignition delay times of a “real” synthetic jet fuel (S8) were measured using an atmospheric pressure flow reactor facility. Experiments were performed between 900 K and 1200 K at equivalence ratios from 0.5 to 1.5. Ignition delay time measurements were also performed with JP8 fuel for comparison. Liquid fuel was prevaporized to gaseous form in a preheated nitrogen environment before mixing with air in the premixing section, located at the entrance to the test section of the flow reactor. The experimental data show shorter ignition delay times for S8 fuel than for JP8 due to the absence of aromatic components in S8 fuel. However, the ignition delay time measurements indicate higher overall activation energy for S8 fuel than for JP8. A detailed surrogate kinetic model for S8 was developed by validating against the ignition delay times obtained in the present work. The chemical composition of S8 used in the experiments consisted of 99.7 vol% paraffins of which approximately 80 vol% was iso-paraffins and 20% n-paraffins. The detailed kinetic mechanism developed in the current work included n-decane and iso-octane as the surrogate components to model ignition characteristics of synthetic jet fuels. The detailed surrogate kinetic model has approximately 700 species and 2000 reactions. This kinetic mechanism represents a five-component surrogate mixture to model generic kerosene-type jets fuels, namely, n-decane (for n-paraffins), iso-octane (for iso-paraffins), n-propylcyclohexane (for naphthenes), n-propylbenzene (for aromatics) and decene (for olefins). The sensitivity of iso-paraffins on jet fuel ignition delay times was investigated using the detailed kinetic model. The amount of iso-paraffins present in the jet fuel has little effect on the ignition delay times in the high temperature oxidation regime. However, the presence of iso-paraffins in synthetic jet fuels can increase the ignition delay times by two orders of magnitude in the negative temperature (NTC) region between 700 K and 900 K, typical gas turbine conditions. This feature can have a favorable impact on preventing flashback caused by the premature autoignition of liquid fuels in lean premixed prevaporized (LPP) combustion systems.

Simultaneous Optimization of Configuration and Control for a Passive SCR System

2018 ◽  
Author(s):  
Pingen Chen ◽  
Qinghua Lin
Keyword(s):  
Catalytic Reduction ◽  
Simultaneous Optimization ◽  
Computationally Efficient ◽  
System Architectures ◽  
Aftertreatment System ◽  
In Series ◽  
System Configurations ◽  
Scr System ◽  
And Control ◽  
Passive Scr

The configuration and control of aftertreatment systems have a significant impact on their functionalities and emission control performance. The traditional aftertreatment system configurations, i.e., connections from one aftertreatment subsystem to another subsystem in series, are simple but generally do not yield the optimal aftertreatment system performance. New aftertreatment configurations, in conjunction with new engine and aftertreatment control, can significantly improve engine efficiency and emission reduction performance. However, new configuration design requires human intuition and in-depth knowledge of engine and aftertreatment system design and control. The purpose of this study is to develop a general systematic and computationally-efficient method which enables automated and simultaneous optimization of passive selective catalytic reduction (SCR) system architectures and the associated non-uniform cylinder-to-cylinder combustion (NUCCC) controls based on a newly proposed highly reconfigurable passive SCR model structure and integer partition theory. The proposed method is general enough to account for passive SCR systems with two or more TWC stages. We demonstrate through this case study that the optimized passive SCR configuration, in conjunction with the optimized NUCCC control, can reduce the NH3 specific fuel consumption by up to 21.90%.

Performance Optimization of High-pressure SCR System in a Marine Diesel. Part II: Catalytic Reduction and Process

2018 ◽  
Vol 62 (1-4) ◽  
pp. 40-48 ◽  
Author(s):  
Yuanqing Zhu ◽  
Rongpei Zhang ◽  
Song Zhou ◽  
Chunan Huang ◽  
Yongming Feng ◽  
...  
Keyword(s):  
High Pressure ◽  
Performance Optimization ◽  
Catalytic Reduction ◽  
Marine Diesel ◽  
Scr System

scholarly journals Numerical Investigation on the Intraphase and Interphase Mass Transfer Limitations for NH3-SCR over Cu-ZSM-5

Processes ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1966
Author(s):  
Shiyong Yu ◽  
Jichao Zhang
Keyword(s):  
Pressure Drop ◽  
Catalytic Reduction ◽  
Nox Reduction ◽  
Catalytic Performance ◽  
No Oxidation ◽  
Relative Pressure ◽  
Nh3 Scr ◽  
Nox Conversion ◽  
Nh3 Adsorption ◽  
Media Channels

A systematic modeling approach was scrutinized to develop a kinetic model and a novel monolith channel geometry was designed for NH3 selective catalytic reduction (NH3-SCR) over Cu-ZSM-5. The redox characteristic of Cu-based catalysts and the variations of NH3, NOx concentration, and NOx conversion along the axis in porous media channels were studied. The relative pressure drop in different channels, the variations of NH3 and NOx conversion efficiency were analyzed. The model mainly considers NH3 adsorption and desorption, NH3 oxidation, NO oxidation, and NOx reduction. The results showed that the model could accurately predict the NH3-SCR reaction. In addition, it was found that the Cu-based zeolite catalyst had poor low-temperature catalytic performance and good high-temperature activity. Moreover, the catalytic reaction of NH3-SCR was mainly concentrated in the upper part of the reactor. In addition, the hexagonal channel could effectively improve the diffusion rate of gas reactants to the catalyst wall, reduce the pressure drop and improve the catalytic conversion efficiencies of NH3 and NOx.

An Experimental Study for NOx - Emission Reduction with Urea-SCR Technology in Vehicular Diesel Engines

2011 ◽  
Vol 71-78 ◽  
pp. 2089-2093 ◽  
Author(s):  
Qian Wang ◽  
Ming Xing Zhou ◽  
Bao Yi Wang
Keyword(s):  
Fuel Consumption ◽  
Control Strategy ◽  
Catalytic Reduction ◽  
Water Solution ◽  
Open Loop ◽  
Loop Control ◽  
Consumption Ratio ◽  
Future Emission ◽  
System Configurations ◽  
Scr System

In order to fulfill future emission standards for middle and heavy-duty vehicles like state Ⅳ and Ⅴ, advanced measures on exhaust gas and engine functionality are required. Selective Catalytic Reduction (SCR) technology is the unique technology currently which can improve the emission and reduce fuel consumption simultaneously. Firstly the reductants and its chemical reactions, SCR system configurations and its working principle and urea dosing control strategy are introduced. Then tests are conducted on a diesel engine with SCR system at bench. The results of ESC cycle show that NOx emission is decreased by more than 67% with the open-loop control strategy. Additionally, the urea and fuel consumption and ammonia leakage have been compared and analyzed respectively, the experiment data indicates that the urea water solution consumption ratio is only 5.7% of fuel for this SCR system, while its average ammonia slip is below 5 ppm.

Sign in / Sign up

Export Citation Format

Share Document