Research of Microwave - Ethanol Auxiliary V2O5-WO3/TiO2 SCR Catalyst Regeneration Experiment

2014 ◽  
Vol 1015 ◽  
pp. 619-622
Author(s):  
Zhuang Kun Wang
Keyword(s):  
Catalytic Reduction ◽  
Physical Structure ◽  
Catalyst Regeneration ◽  
Practical Significance ◽  
Regeneration Process ◽  
Recovery Method ◽  
Scr Catalyst ◽  
Scr Catalysts ◽  
Element Enrichment ◽  
Scr System

Using selective catalytic reduction (SCR) that takes NH3 as the reducing agent to remove NOx is one of the most often used coal-fired flue gas denitration technology that of the highest denitration efficiency. As the core of the SCR system, catalyst is the important factors that affect the whole SCR system denitration efficiency. As the growth of the running time, catalyst tends to lose active energy because of the surface channel jam and toxic element enrichment and deactivation. Each year the deactivation catalyst regeneration process, can save a lot of money, thus help to avoid pollution of the environment. So study of the SCR catalyst regeneration technology is around the corner, which is of great practical significance for lowering the cost of the SCR system, promoting the application of the SCR technology, and protecting the environment. In this paper, the research takes vanadium series SCR catalysts as the object to study the regeneration technology of catalyst, new physical structure recovery method, and effect of regeneration process in the treatment on the performance of catalyst.

Factors Affecting Mercury Oxidation by SCR Catalysts

2014 ◽  
Vol 986-987 ◽  
pp. 755-760
Author(s):  
Wen Du ◽  
Li Bao Yin ◽  
Yu Qun Zhuo ◽  
Qi Sheng Xu ◽  
Liang Zhang ◽  
...  
Keyword(s):  
Active Sites ◽  
Catalytic Reduction ◽  
Space Velocity ◽  
Injection Rate ◽  
Mercury Oxidation ◽  
Factors Affecting ◽  
Scr Catalysts ◽  
Negative Effect ◽  
Oxidation Efficiency ◽  
Scr System

The application of selective catalytic reduction (SCR) system may affect mercury speciation in coal-combustion flue gas. The factors affecting mercury oxidation efficiency by SCR catalysts have been evaluated in this research. The influencing factors investigated included hydrogen chloride (HCl), sulfur dioxide (SO2), ammonia (NH3) injection rate and space velocity. HCl had been found to promote mercury oxidation significantly. The Eley-Rideal mechanism was proven to be suitable to explain the reaction of Hg0 and HCl. NH3 injection had a strong negative effect to mercury oxidation. The deactivation of aged SCR catalysts was mainly due to loss of active sites.

scholarly journals Deactivation of Cu/SSZ-13 NH3-SCR Catalyst by Exposure to CO, H2, and C3H6

Catalysts ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 929 ◽  
Author(s):  
Auvray ◽  
Mihai ◽  
Lundberg ◽  
Olsson
Keyword(s):  
Flow Reactor ◽  
Catalytic Reduction ◽  
Plug Flow ◽  
Acid Sites ◽  
Drift Spectroscopy ◽  
Scr Catalyst ◽  
Nh3 Scr ◽  
Scr Catalysts ◽  
Nh3 Oxidation ◽  
Diffuse Reflectance Infrared

Lean nitric oxide (NOx)-trap (LNT) and selective catalytic reduction (SCR) are efficient systems for the abatement of NOx. The combination of LNT and SCR catalysts improves overall NOx removal, but there is a risk that the SCR catalyst will be exposed to high temperatures and rich exhaust during the LNTs sulfur regeneration. Therefore, the effect of exposure to various rich conditions and temperatures on the subsequent SCR activity of a Cu-exchanged chabazite catalyst was studied. CO, H2, C3H6, and the combination of CO + H2 were used to simulate rich conditions. Aging was performed at 800 °C, 700 °C, and, in the case of CO, 600 °C, in a plug-flow reactor. Investigation of the nature of Cu sites was performed with NH3-temperature-programed desorption (TPD) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) of probe molecules (NH3 and NO). The combination of CO and H2 was especially detrimental to SCR activity and to NH3 oxidation. Rich aging with low reductant concentrations resulted in a significantly larger deactivation compared to lean conditions. Aging in CO at 800 °C caused SCR deactivation but promoted high-temperature NH3 oxidation. Rich conditions greatly enhanced the loss of Brønsted and Lewis acid sites at 800 °C, indicating dealumination and Cu migration. However, at 700 °C, mainly Brønsted sites disappeared during aging. DRIFT spectroscopy analysis revealed that CO aging modified the Cu2+/CuOH+ ratio in favor of the monovalent CuOH+ species, as opposed to lean aging. To summarize, we propose that the reason for the increased deactivation observed for mild rich conditions is the transformation of the Cu species from Z2Cu to ZCuOH, possibly in combination with the formation of Cu clusters.

Catalytic Control of NOx, CO, and NMHC Emissions From Stationary Diesel and Dual-Fuel Engines

1992 ◽  
Vol 114 (3) ◽  
pp. 597-601 ◽  
Author(s):  
R. W. Bittner ◽  
F. W. Aboujaoude
Keyword(s):  
Catalyst Surface ◽  
Catalytic Reduction ◽  
Catalyst System ◽  
Oxidation Catalyst ◽  
Dual Fuel ◽  
Catalyst Structure ◽  
Scr Catalyst ◽  
Heavy Hydrocarbons ◽  
Dual Fuel Engines ◽  
Scr System

Selective Catalytic Reduction (SCR) and oxidation catalyst technology have been applied to a stationary diesel and dual-fuel (natural gas and #2 diesel) engine for catalytic control of nitrogen oxides (NOx), carbon monoxide (CO), and nonmethane hydrocarbon (NMHC) emissions. At rated conditions, NOx emissions have been effectively reduced by up to 90 percent, with little loss of SCR catalyst performance after 850 hours of operation. Using adequate control of the ammonia (NH3) feed, the SCR system was capable of maintaining NH3 slip to 10 ppm or less. CO and NMHC were reduced by 93 and 85 percent, respectively. Little soot was observed on the surface of the catalyst due to the use of a catalyst system that minimizes the buildup of heavy hydrocarbons on the catalyst surface. In addition, the catalyst structure effectively resisted the buildup of sulfur compounds that could cause premature deactivation of the catalyst.

The Regeneration Effect of H2SO4 on V-W-TiO2 SCR Catalyst Deactivated by Alkali Metal

2017 ◽  
Author(s):  
Yongbo Du ◽  
Chang’an Wang ◽  
Xiaoyang Wei ◽  
Qiang Lv ◽  
Yonggang Zhao ◽  
...  
Keyword(s):  
Mechanical Strength ◽  
Alkali Metals ◽  
Catalytic Reduction ◽  
Sodium Content ◽  
Fresh Catalyst ◽  
Scr Catalyst ◽  
Scr Catalysts ◽  
So2 Resistance ◽  
Zhundong Coal ◽  
Regeneration Effect

The sodium content in Zhundong coal is extremely high, which can accelerate the deactivation of the V-W-TiO2 selective catalytic reduction (SCR) catalysts. Sulfuric acid solution (H2SO4) washing has been verified as a famous method to regenerate the de-NOx performance for catalyst which has been poisoned by alkali metals. However, the performance of the regenerated catalyst in practice still needs to be investigated. In the present study, the resistance to sulfur dioxide (SO2) and the mechanical strength of the regenerated catalyst were experimentally studied as well as the continuous operation performances under several conditions. The results indicate that the de-NOx activity of H2SO4 regenerated catalyst is chemically stable below 300 °C and thermally stable below 450 °C. However, the catalytic activity of the regenerated catalyst could suffer a decline during operating under the SCR atmosphere at 450 °C, which is different from the fresh catalyst. Besides, the regenerated catalyst shows good SO2 resistance, whereas the mechanical strength is likely to be affected by the H2SO4 washing treatment.

scholarly journals Combination of LNT and SCR for NOx reduction in passenger car applications

2014 ◽  
Vol 157 (2) ◽  
pp. 60-67
Author(s):  
Teuvo MAUNULA
Keyword(s):  
Catalytic Reduction ◽  
Nox Reduction ◽  
Main Reaction ◽  
Maximum Temperature ◽  
Lean Nox Trap ◽  
Particulate Emissions ◽  
Passenger Cars ◽  
Experimental Conditions ◽  
Scr Catalyst ◽  
Scr Catalysts

The removal of NOx and particulate emissions in light-duty diesel vehicles will require the use of aftertreatment methods like Diesel Particulate Filters (DPF) and Selective Catalytic Reduction (SCR) with urea and Lean NOx Trap (LNT) (Euro 6 and beyond). A new concept is the combination of LNT + SCR, which enables on-board synthesis of ammonia (NH3), which reacts with NOx on the SCR catalyst. The main application for this kind system will be lighter passenger cars, where LNTs may be used instead of full urea-SCR system. That particular combinatory system was investigated by developing platinum (Pt) and rhodium (Rh) containing LNTs and SCR catalysts in this study. In the use conditions, the maximum temperature may reach temperatures up to 800 °C and NOx reduction reactions should proceed without NO2 assistance in the SCR position after LNT and DPF. PtRh/LNT with the total loadings of 85 g/cft (2.8 g/L) and higher resulted in a high NOx efficiency above 80–90% with a broad operation window in the laboratory simulations. In the experimental conditions, a higher NH3 concentration after LNT was essential to simulate well the operation of SCR catalysts. The developed Cu-SCR catalyst showed a high hydrothermal durability up to the ageing temperature of 800 °C and a wide operation window without the NO2 assistance (NO only in feed). Fe-SCR and V-SCR catalysts were more dependent on NO2. A studied concept had an air injection after LNT to keep SCR condition always in lean side, where the SCR reaction was promoted by oxygen resulting in high reduction selectivity to nitrogen (N2) without NH3 emissions. The simulations in reaction conditions and system design resulted in the proposals for the optimal design and main reaction mechanism in DOC + DPF + LNT + SCR systems.

scholarly journals Hybrid Technology for DeNOxing by LNT-SCR System for Efficient Diesel Emission Control: Influence of Operation Parameters in H2O + CO2 Atmosphere

Catalysts ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 228
Author(s):  
Marina Cortés-Reyes ◽  
Concepción Herrera ◽  
María Ángeles Larrubia ◽  
Luis J. Alemany
Keyword(s):  
Catalytic Reduction ◽  
Scale Up ◽  
Lean Nox Trap ◽  
Scr Catalyst ◽  
Temperature Range ◽  
Small Pore ◽  
Lean Nox ◽  
Operation Parameters ◽  
The Rich ◽  
Scr System

The behavior and operation parameters were analyzed for the hybrid LNT-SCR (Lean NOx-Trap–Selective Catalytic Reduction) system with advanced catalyst formulations. Pt-Ba-K/Al2O3 was used as an NSR (NOx Storage and Reduction) or LNT catalyst effective in NOx and soot simultaneous removal whereas Cu-SAPO-34 with 2 wt.% of copper inside the structure was the small pore zeolite employed as the SCR catalyst. Under alternating and cyclic wet conditions, feeding volumetric concentrations of 1000 ppm of NO, 3% of O2, 1.5% of water, 0.3% of CO2, and H2 as a reductant, the NOx-conversion values were above 95% and a complete mineralization to nitrogen was registered using θ ≤ 3 (20 s of regeneration) and a hydrogen content between 10,000 and 2000 ppm in the whole temperature range tested. An excess of hydrogen fed (above 1% v/v) during the rich phase is unnecessary. In addition, in the low temperature range below 250 °C, the effect is more noticeable due to the further ammonia production and its possible slip. These results open the way to the scale up of the coupled catalytic technologies for its use in real conditions while controlling the influence of the operation map.

Get the Most Out of Your Gas Turbine SCR NOx Abatement System

2003 ◽  
Author(s):  
Martin F. Collins ◽  
S. Mario DeCorso ◽  
David L. Moen
Keyword(s):  
Catalytic System ◽  
System Performance ◽  
Catalytic Reduction ◽  
Exhaust Gas ◽  
Scr Catalyst ◽  
Equipment Operation ◽  
Scr System ◽  
Scr Of Nox ◽  
Design Construction ◽  
Turbine Exhaust

Selective catalytic reduction (SCR) of NOx from turbine exhaust has been used successfully for at least 12 years. With this process, ammonia (NH3) is mixed with the exhaust gas before it passes through the SCR catalyst where the ammonia reacts selectively with the NOx, producing nitrogen and water. To make this simple reaction work properly over the life of the plant requires attention to issues during design and fabrication of the equipment, operation of the system, and quality control. There are a total of more than 25 issues involved. When all of these issues are recognized and addressed properly, the SCR catalytic system will produce the specified performance for the planned life of the catalyst. This paper identifies, describes, and discusses each of these issues. Most cases of unsatisfactory SCR turbine system performance can be traced to one or more of these issues being overlooked or not addressed properly in the design, construction, or operation of the catalytic system. The purpose of this paper is to make turbine system users aware of what must be done to get the most out of their SCR system.

Modeling of Urea-Water Solution Injection Spray in SCR System

2012 ◽  
Vol 232 ◽  
pp. 583-587
Author(s):  
Nayak S. Nagaraj ◽  
N. Kapilan ◽  
Prabhu S. Sadashiva
Keyword(s):  
Catalytic Reduction ◽  
Water Solution ◽  
Exhaust Gas ◽  
Scr Catalyst ◽  
Exhaust Gas Aftertreatment ◽  
Study Results ◽  
Exhaust Stream ◽  
Experimental Values ◽  
Scr System ◽  
Aftertreatment Systems

To control the emissions from the diesel engines of modern automobiles, it requires the development of adequate and advanced exhaust gas aftertreatment devices. Selective Catalytic Reduction (SCR) is a method that can be used in mobile diesel engine aftertreatment systems to reduce harmful NOx emissions. Due to the toxicity and handling problems of ammonia, currently injection of a liquid Urea-Water Solution (UWS) into the exhaust stream approach is used. The water evaporates and the urea undergoes thermal decomposition producing ammonia that reacts with the NOx in the exhaust gas inside a SCR catalyst to produce nitrogen and water vapor. This work presents the study of UWS injection spray using commercial available CFD code, Fire v8.3. The evaporation of water from a single droplet of UWS is investigated theoretically and droplets are treated with Lagrangian particle tracking. Simulation study at different exhaust gas temperatures and injector locations is carried out and compared with experimental values. Thus, the present study results predict the local distribution and the conversion of the reducing agent.

scholarly journals Numerical Simulation to Reduce NOx of Diesel Engine Urea-SCR System

2014 ◽  
Vol 8 (1) ◽  
pp. 643-647 ◽  
Author(s):  
Zhang Hui ◽  
Xu Boyan ◽  
Wang Chuansheng
Keyword(s):  
Concentration Distribution ◽  
Optimization Design ◽  
Catalytic Reduction ◽  
Reducing Agent ◽  
Fuel Injector ◽  
Scr Catalyst ◽  
Numerical Analytical Method ◽  
Scr System ◽  
The Mathematical Model ◽  
Good Agreement

By using computational fluid dynamics and chemical reaction dynamics method, the mathematical model of SCR (selective catalytic reduction) system was established. On the basis of the verified feasibility, by CFD numerical analytical method, the reducing agent inside the catalysts concentration distribution was compared under different added urea schemes. Jet direction and the form of fuel injector were studied on the basis of the effects of reducing agent concentration distribution. The simulation result shows good agreement with the experimental data. The simulated results can be utilized in optimization design of the diesel SCR catalyst.

TWC-SCR Aftertreatment System Evaluation for a Lean Burn Gasoline Engine Operating in HCCI, SACI, and SI Combustion Modes

2016 ◽  
Author(s):  
Jordan Easter ◽  
Stanislav V. Bohac
Keyword(s):  
Conversion Efficiency ◽  
Gasoline Engine ◽  
Fuel Efficiency ◽  
Compression Ignition ◽  
Scr Catalyst ◽  
Advanced Combustion ◽  
Nox Conversion ◽  
Combustion Modes ◽  
Scr System ◽  
Nox Conversion Efficiency

Low temperature and dilute Homogenous Charge Compression Ignition (HCCI) and Spark Assisted Compression Ignition (SACI) can improve fuel economy and reduce engine-out NOx emissions to very low values, often less than 30 ppm. However, these combustion modes are unable to achieve stringent future regulations such as SULEV 30 without the use of lean aftertreatment. Though active selective catalytic reduction (SCR) with urea injection and lean NOx traps (LNT) have been investigated as options for lean gasoline engines, a passive TWC-SCR system is investigated in this work because it avoids the urea storage and dosing hardware of a urea SCR system, and the high precious metal cost of an LNT. The TWC-SCR concept uses periodic rich operation to produce NH3 over a TWC to be stored on an SCR catalyst for subsequent NOx conversion during lean operation. In this work a laboratory study was performed with a modified 2.0 L gasoline engine that was cycled between lean HCCI and rich SACI operation, or between lean and rich SI (spark ignited) combustion, to evaluate NOx conversion and reduced fuel consumption. Different lambda values during rich operation and different times held in rich operation were investigated. Results are compared to a baseline case in which the engine is always operated at stoichiometric conditions. SCR system simulations are also presented that compare system performance for different levels of stored NH3. With the configuration used in this study, lean/rich HCCI/SACI operation showed a maximum NOx conversion efficiency of 10%, while lean/rich SI operation showed a maximum NOx conversion efficiency of 60%. However, if the low conversion efficiency of lean/rich HCCI/SACI operation could be improved through higher brick temperatures or additional SCR bricks, simulation results indicate TWC-SCR aftertreatment has the potential to provide near-zero SCR-out NOx concentration and increased system fuel efficiency. In these simulations, fuel efficiency improvement relative to stoichiometric SI were 7 to15% for lean/rich HCCI/SACI with zero tailpipe NOx and −1 to 5% for lean/rich SI with zero tailpipe NOx emissions. Although previous work indicated increased time for NH3 to start forming over the TWC during rich operation, less NH3 production over the TWC per fuel amount, and increased NH3 slip over the SCR catalyst for advanced combustion systems, if NOx conversion efficiency could be enhanced, improvements in fuel economy and low engine-out NOx from advanced combustion modes would more than make up for these disadvantages.

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