Reduction Of Nitrogen Oxides Research Articles

Analysis of ship electrical load management to reduce exhaust gas emissions in landing platform dock (LPD) vessel class

This paper investigates the impact of electrical load management on reducing exhaust gas emissions in Landing Platform Dock (LPD) class vessels. The study focuses on the implementation of Integrated Fully Electric Propulsion (IFEP) systems and Variable Speed Drives (VSD) to enhance energy efficiency and minimize environmental impact. The conventional Diesel Engine Propulsion system in LPD vessels often results in high fuel consumption and significant emissions, particularly under non-optimal operating conditions. By transitioning to an IFEP system and optimizing electrical load management using VSD, the study demonstrates a substantial reduction in carbon dioxide (CO₂), nitrogen oxides (NOₓ), and sulfur oxides (SOₓ) emissions. The results indicate a potential emission reduction of up to 40%, alongside a 20% improvement in overall energy efficiency. Additionally, the operational benefits of these technologies include increased flexibility, reduced maintenance costs, and extended equipment lifespan. The findings underscore the importance of adopting advanced propulsion and load management technologies in naval vessels to meet stricter environmental regulations and support sustainable maritime operations. This study provides a framework for future research and practical applications in expanding these technologies across different ship types and operational scenarios.

Exploration for Chemical Filter Cartridges that Can Reduce Nitrogen Oxides, a Common Factor in the Formation of Nitrosamines

Exploration for Chemical Filter Cartridges that Can Reduce Nitrogen Oxides, a Common Factor in the Formation of Nitrosamines

An Assessment of the Performance and Emissions of an Otto Power Generator Group Operating with Wet Ethanol at a High Volumetric Compression Ratio

This work presents an experimental study of the performance and emissions of an internal combustion engine operating in the Otto cycle with a high volumetric compression ratio (17:1). The engine was initially fueled with the standard ethanol used in Brazil, with 7% distilled water (E93W07); we then studied the effects of using different ethanol-in-water mixtures, or ‘wet ethanol’, with 17%, 27%, 37%, and 47% distilled water concentrations. The tests were carried out with power loads of 5.0–25.0 kW at 5.0 kW intervals and with power loads of 27.5–35.0 kW at 2.5 kW intervals, whether by adding up the loads or by taking them away. The ignition timing was changed to evaluate each load imposed on the engine to avoid knocking. Specific fuel consumption (SFC), brake thermal efficiency (BTE), carbon dioxide emissions (CO2), carbon monoxide (CO), nitrogen oxides (NOx), and total hydrocarbon content (THC), as well as the internal pressure in the cylinder and the heat release rate, were measured, and the results are compared. The results show a reduction in CO and NOx and an increase in THC emissions. However, there were no significant changes in CO2 emissions when the distilled water percentage in ethanol increased. Regarding the brake thermal efficiency, it was observed that it remained approximately constant for all blends, with the same load being applied to the engine shaft, reaching a maximum value of 35%. The results obtained confirm the technical feasibility of operating an internal combustion engine in the Otto cycle with a high volumetric compression ratio using ethanol with up to 47% distilled water without significant loss of performance.

Deactivation Mechanism of Spent TiO2-Based Selective Catalytic Reduction (SCR) Catalysts and State-of-the-Art Recycling Technologies.

Nitrogen oxides (NOx) make up a group of gases that are mainly formed during the combustion of fossil fuels at high temperatures. NOx contributes to environmental degradation by forming acid rain and enhancing global warming. Exposure to air with a high concentration of NOx can aggravate respiratory diseases, particularly asthma. The elimination of NOx in practical applications mainly proceeds through selective catalytic reduction (SCR) of NOx with NH3 to harmless N2 and H2O. One practical issue of the SCR process is the deactivation of TiO2-based SCR catalysts. In addition, growing numbers of spent SCR catalysts present a serious waste-management challenge for recyclers at end of life. It is therefore crucial to disclose the deactivation mechanism of the spent TiO2-based NH3-SCR catalysts and propose effective recycling technologies for waste valorization. Here we outline the catalyst deactivation pathways for TiO2-based SCR catalysts and critically review methods of improving the direct sustainability of spent catalysts, in areas such as direct regeneration and recovery of spent catalysts. Through this review, the challenges, solutions, and future strategies for handling spent SCR catalysts are clarified for future studies of application on an industrial scale.

A comparative study of diesel engine fueled by neem and ethanol biodiesel: performance, emissions, and sustainability assessment

Examining the emission characteristics of compression ignition (CI) engines using neem biodiesel in conjunction with ethanol and different percentages of exhaust gas recirculation (EGR) was the aim of the present research. In this experiment, a four-stroke, air-cooled, single-cylinder diesel engine with a rated power output of 5.2 kW was used to change the EGR percentage from 0% to 20%. Examining engine emission parameters and comparing them to diesel fuel was the aim of the research. The experiment indicates that as the EGR fraction in the fresh mixture rises, nitrogen oxide emissions fall. the most percentage of nitrogen oxide reduction as compared to diesel operating on its own. Using ethanol with varying EGR rates may lower emissions of hydrocarbons and carbon monoxide.

How Do the Morphology and Crystal Facet of CeO2 Determine the Catalytic Activity toward NO Removal?

Cerium oxide (CeO2) exhibits application potential for the selective catalytic reduction of nitrogen oxides (NOx) with NH3 (NH3-SCR). The crystal facets and morphology of CeO2 have a vital impact on the catalytic performance of NH3-SCR. However, the precise influence mechanisms on SCR activity remain elusive. In this work, CeO2 is successfully synthesized with three distinct crystal facets and nine diverse morphologies. This investigation involves a comprehensive blend of theoretical analysis and experiments, to gain profound insights into the underlying mechanisms governing the SCR catalytic activity concerning morphology and crystal facets. By closely integrating density functional theory (DFT) calculations, Ab initio thermodynamic analysis, SCR catalytic activity experiments, and X-ray photoelectron spectroscopy experiments, it is discovered that the concentration of surface-active oxygen (O*) plays a pivotal role in determining the catalytic activity of CeO2 in SCR reactions, as opposed to factors like specific surface area or oxygen defect concentration. This experimental-theoretical joint study provides design principles of CeO2 catalysts for NO removal.

Mechanism of SO2 effect on the simultaneous removal of NOx and propane over bifunctional NiMn2O4-CeO2 catalysts

Nitrogen oxides (NOx) and volatile organic compounds (VOCs) are the main pollutants in flue gas, and the synergistic removal of NOx and VOCs in the presence of SO2 is still a challenge. In this work, the microstructure of NiMn2O4-CeO2 catalysts and the distribution of sulfur-containing substances were studied to reveal the inactivation mechanism of sulfur poisoning. NOx conversion could reach more than 80 % at 100–250 °C, and C3H8 conversion could achieve 90 % at 210 °C in the synergistic reaction on NiMn2O4-CeO2 catalyst, which has dual active sites with propane oxidation and SCR reactions carried out at Mn and Ni sites, respectively. In addition, the intrinsic effect of SO2 on propane oxidation and NOx reduction were investigated by decoupling. For propane oxidation, mechanistic studies have shown that manganese sulfate generated by SO2 hindered further reactions by inhibiting the breaking of the CC bond. For denitration reaction, the generation of sulfate not only resulted in electron transfer from Ni to Mn thereby reducing reaction activity, but also blocked the L-H pathway by inhibiting NO adsorption. This work provides guidelines and strategies to mitigate SO2 poisoning in the simultaneous removal of NOx and light alkane.

An Experimental Investigation on Enhancing Nitrogen Oxides Reduction of Non-Thermal Plasma (NTP) Aftertreatment System with Silver-Base Catalyst with NTP Downstream SCR Catalyst Configuration

An Experimental Investigation on Enhancing Nitrogen Oxides Reduction of Non-Thermal Plasma (NTP) Aftertreatment System with Silver-Base Catalyst with NTP Downstream SCR Catalyst Configuration

Effects of valley topography on ozone pollution in the Lanzhou valley: A numerical case study

Valley topography is recognized for its role in constraining pollutant dispersion, which frequently results in elevated pollutant concentrations within valley regions. However, the specific mechanisms by which valley topography influences daytime ozone (O3) production, nighttime O3 depletion, and diurnal variations in O3 concentrations remain inadequately understood. This study employs the online WRF-Chem air quality model to conduct sensitivity analyses, examining the effects of valley topography on summer O3 concentrations in Lanzhou, a valley city in western China. The results indicate that valley topography generally reduces surface temperature and wind speed while also lowering the planetary boundary layer height (PBLH), which ultimately leads to increased concentrations of primary pollutants. Nevertheless, the impact of valley terrain on O3 is time-dependent, with concentrations decreasing during the day and increasing at night. In Lanzhou, valley topography contributes to a 4.4% reduction in daytime O3 concentrations. This reduction is largely due to the blocking of solar radiation by surrounding mountains, which results in a 7% decrease in shortwave radiation (SR) and a 17% decline in PBLH, subsequently limiting O3 chemical production. Although valley topography restricts pollutant dispersion, the overall effect during the day is a net decrease in O3 levels. In contrast, nighttime valley topography leads to a notable 19.8% increase in O3 concentrations. This increase is driven by mountain breezes transporting O3-rich air from the slopes into urban areas, along with a 67.4% reduction in nitrogen oxide (NO) levels. Despite intensified NO titration within the valley, the combined effect of these local wind patterns contributes to elevated O3 concentrations at night. These findings offer valuable insights into the unique factors contributing to urban O3 pollution in areas with complex valley topography.

Low-Temperature NH3-SCR Technology for Industrial Application of Waste Incineration: An Overview of Research Progress

Selective catalytic reduction of nitrogen oxides with NH3 (NH3-SCR) was investigated deeper and deeper with poisoning factors such as H2O, SO2, heavy metals, etc. In order to remove the reheating process before the SCR reactor, the application trend of NH3-SCR technology in the non-power industry is concentrated on the condition of low temperature even ultra-low temperature. The present study summarizes the research process of SO2 and H2O resistance of NH3-SCR catalysts under low temperatures related to the working conditions of municipal solid waste incineration plants. In detail, the effects of a high content of H2O and low concentration of SO2 are reviewed. Other factors such as heavy metals, alkali, or alkaline earth metals in the reaction system, synergistic removal of NOx, polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are addressed. Finally, the catalytic performance of assembled monolithic catalysts and pilot-scale experiments are also analyzed for the possibility of industrial application. Hopefully, in view of the questions outlined in this study, valuable insights could be taken into consideration for the development of NH3-SCR in waste incineration.

STUDYING THE EFFECT OF MAGNETIC FLUX ON DIESEL FUEL LINE ON SOME PERFORMANCE AND EMISSION OF DIESEL ENGINE

This study aimed to investigation was carried out to evaluate the performance and product emission of four cylinder 4- stroke water cooled direct injection (DI) diesel engine fueled by permanent magnet exposed diesel fuel compared with diesel fuel (DF). Three levels of magnet field intensity were used including Diesel fuel exposer to 3000 Gauss (DG3), Diesel fuel exposer to 5000 Gauss (DG5) and Diesel fuel exposer to 9000 Gauss (DG9) fuel respectively. Permanent magnetic device was employed and installed on fuel line before interring high pressure fuel injection pump . The engine run at constant speed 1500rpm(revolution per minute) and loaded by two levels 4.5 kW and 9 kW represented as L1and L2 respectively. Results obtained showed that fuel DG5 registered an increased in thermal efficiency(TE) about 20.09% at load L1 compared with DF. Maximum reduction in brake specific fuel consumption (bsfc) about 12.12%, when using DG5 fuel at load 1 compared to DF fuel. All exhaust emission Unburned Hydrocarbon (UHC), Carbon Monoxide (CO), Carbon Dioxide (CO2),Particular Maters (PM), and Nitrogen Oxides (NOx) are decreased when diesel fuel treated with different magnetic intensities 3000,5000 and 9000 Gauss. Compared with conventional diesel fuel. Maximum reduction in PM,HC,NOx,CO2,and CO about 16.56-27.08%, 3.89–64.26%, 4.79–7.91%, 4.05-5.71and 11.46-53.48% respectively. CO2 emission was increased by 1.65-4.28 at DG5 with L1 and L2 respectively due to the operating conditions.

Contrasting Domestic and Global Impacts of Emission Reductions in China on Tropospheric Ozone

AbstractSustained near‐surface ozone pollution despite stringent emission controls in China has drawn wide attention. However, how such rapid regional emission reductions affect global tropospheric ozone remains unexplored. Here, using an ensemble of measurements and global model simulations, we find Chinese emission reductions during 2013–2020 have increased domestic surface ozone; particularly in North China, they have decreased the global tropospheric ozone burden by 2.7 Tg (54% of China's anthropogenic contribution and 7% of global anthropogenic contribution in 2019) and ozone radiative forcing by 8.8 mW m−2 (64% of China's anthropogenic contribution and 9% of global anthropogenic contribution in 2019). Nitrogen oxides (NOx) associated nonlinear chemistry and height‐dependent atmospheric transport patterns primarily cause the contrasting impacts. Future Chinese NOx emission controls would continue to decrease global tropospheric ozone, while regional surface ozone may still increase unless NOx reductions exceed ∼53% of the 2019 level. Our results reveal the substantial benefit of regional emission reductions in China on global tropospheric ozone mitigation.

Constructing dual-channel carrier transport in AgBr/BiOBr/Ag3PO4 heterojunctions for enhanced photocatalytic NO removal

Efficient and stable photocatalysts are indispensable for effectively reducing nitrogen oxide (NOx) emissions. This study presents a facile method for synthesizing AgBr/BiOBr/Ag3PO4 composites and investigates their application in photocatalytic NO removal. The optimized composite exhibited notable performance, achieving 54.95 % removal of NO (approximately 568 ppb reduced to 256 ppb) under visible light irradiation, which is about 1.6 and 2.0 times higher than single Ag3PO4 (34.95 %) and BiOBr (28.01 %), respectively. Comprehensive physicochemical characterization highlighted enhancements in light absorption and the generation of reactive radicals within the AgBr/BiOBr/Ag3PO4 composite. The favorable electronic structure, characterized by well-aligned redox band positions, facilitated efficient dual carrier transport routes, thereby promoting the separation of photo-generated charge carriers. Additionally, in-situ DRIFTS analysis revealed that the composite facilitated the conversion of intermediates into nitrates during the NO purification process. This work contributes valuable insights into designing and preparing of ternary heterojunction photocatalysts with dual carrier transport channels, advancing strategies for achieving superior photocatalytic performance.

An experimental and ANN analysis of ammonia energy integration in biofuel powered low-temperature combustion engine to enhance cleaner combustion

In the pursuit of global net-zero emissions targets and cleaner combustion technologies, researchers are increasingly turning to innovative solutions. Ammonia, as a carbon-free fuel, holds promise for achieving low emissions and efficient combustion. This study explores the potential synergies of various ammonia shares (20 %, 40 %, and 60 %) combined with Citronella biofuel in a Low-Temperature Combustion (LTC) Reactivity Controlled Compression Ignition (RCCI) engine. Comparative analysis between a 40 % ammonia blend Citronella biofuel (A40) and a Standard Diesel (SDL) in an RCCI engine demonstrates significant reductions in oxides of nitrogen (by 17 %), carbon dioxide (by 6.6 %), and smoke (by 9.8 %), along with a notable enhancement in Brake Thermal Efficiency (BTE) by 5.4 % for A40. The validation of results using an Artificial Neural Network (ANN) model shows robust coefficients of determination (97 %), high R values (0.9945–0.9995), and low Root Mean Square Error values (ranging from 0.0219 to 0.0483). These findings strongly support the efficacy of the A40 blend, positioning it as a promising and viable alternative fuel for achieving cleaner combustion in LTC-RCCI engines.

Investigating Respiratory Disease Transmission Patterns Around the Figuil Cement Works

The objective of this research is to examine the dissemination of respiratory illnesses, exacerbated by the airborne pollutants emitted by the Figuil cement works, among the local population residing in the vicinity. The primary objective is to examine the impact of pollution, particularly the emission of fine particles and noxious gases, on the transmission of respiratory diseases such as asthma, chronic bronchitis and other lung disorders. The modified SEIR (Susceptible-Exposed-Infected-Recovered) epidemiological model is employed for the analysis of transmission dynamics within the community. This model incorporates environmental, health and demographic variables, thereby enabling the simulation of disease transmission as a function of varying pollution levels. Particular emphasis is placed on vulnerable groups, such as children and the elderly, due to immunosenescence, who are more likely to suffer from the adverse effects of pollution. The results will facilitate the formulation of efficacious strategies, including the implementation of awareness-raising campaigns and the introduction of sophisticated systems for the filtration and capture of pollutants at their source, such as fine particle filters or devices for the reduction of nitrogen oxides (NOx), with the objective of limiting the spread of respiratory diseases in at-risk areas and the formulation of suitable control measures.

Boosting low-temperature NH3-SCR performance via mixed-valence cobalt dual active sites

Nitrogen oxides (NOx) have become a critical environmental concern, necessitating the development of highly efficient catalysts for temperature which is lower than 300 °C. Selective catalytic reduction with NH3 (NH3-SCR) is a process where ammonia is the reducing agent for selective catalytic reduction of nitrogen oxides in exhaust gases. The mechanism-property relationship between catalytic active sites and low-temperature denitrification efficiency, however, remains unclear. In this study, we synthesized a series of cobalt-modified nanoparticle catalysts using a scalable citric acid sol-gel method and conducted comprehensive characterizations. Our findings indicate that an optimal cobalt doping rate significantly enhances catalytic activity due to the synergistic effects of reduced nanoparticle size and the dual active sites of Co0/Co2+. Specifically, at a cobalt doping ratio of 1.0, the catalyst demonstrates peak SCR activity, achieving 85.5% NOₓ conversion at 120 °C and complete conversion at 150 °C. These cobalt-modified nanoparticle catalysts feature high deposition of doped Co ions on their surfaces, predominantly as metallic cobalt and CoOx nanoclusters. Compared to undoped samples, the cobalt-doped nanoparticle catalysts exhibit a greater specific surface area, increased acidity, enhanced chemisorbed oxygen, and improved redox properties, all contributing to superior denitrification efficacy. Additionally, Density Functional Theory (DFT) calculations provide assertive evidence into the reaction mechanism, showing that Co2+ sites effectively adsorb and activate NH₃, while Co0 sites are crucial for NO adsorption and activation. The synergistic interaction between Co2+ and Co0 facilitates NN coupling, enhancing overall reaction efficiency. These findings underscore the potential of cobalt-modified catalysts for practical industrial applications, offering robust performance over a wide temperature range and meeting stringent environmental regulations.

Low-Temperature Reduction of NOx by NH3 with Unity Conversion on Nanofilament MnO2/Activated Semi-Coke Catalyst.

Selective catalytic reduction of nitrogen oxides with NH3 at low temperatures remains a crucial goal for industrial applications. However, effective catalysts operating at 70-90 °C are rarely reported, limiting SCR scenarios to high-temperature conditions. Herein, we report a unique MnO2 nanofilament catalyst grown on activated semi-coke synthesized via a one-step in situ hydrothermal approach, which exhibits a stable and marked 100 % conversion rate of NO to N2 with 100 % selectivity at 90 °C, superior to the other prepared structures (nanowires, nanorods, and nanotubes). Temperature-programmed desorption shows a large number of acid sites on MnO2(NFs)/ASC, benefiting the formation of NH4 + ions. Meanwhile, diffuse reflectance infrared Fourier transform spectroscopy reveals the activation of NO with O2 to form bidentate nitrate/bridging nitrate NO2 intermediates via bidentate nitrate species, triggering the Fast SCR with NH3 at low temperatures. Such an effective, easy-to-prepare, and low-cost catalyst paves a new pathway for low-temperature SCR for a wide range of application scenarios.

NOx emission reduction through selective catalytic reduction using copper-based Y zeolite catalyst: experimental investigation and characterization

Growing concerns surrounding global warming and environmental degradation have prompted the widespread adoption of various emission control methodologies, with a particular emphasis on reducing nitrogen oxide (NOx) emissions. Selective catalytic reduction (SCR) stands out as a highly effective technique, applicable not only to large-scale industrial machinery but also to smaller vehicles, aimed at converting NOx emissions into less harmful nitrogen (N2) using specialized catalysts and reductants. This particular study focuses on synthesizing copper-based Y zeolite and conducting experiments using ethanol as a reductant in the exhaust stream of a two-cylinder diesel engine operating under different loads. Furthermore, the catalyst was subjected to thorough characterization using techniques such as Scanning Electron Microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS), X-ray Diffraction (XRD), and Brunauer-Emmet-Teller (BET) analysis. Results indicate that as temperature and engine load increase, the efficiency of NOx conversion also improves. The highest conversion rate, reaching 94.67%, was achieved at 260°C under a 5 kW load. Additionally, average conversion rates of 90%, 90.70%, and 92.62% were observed for loads of 1 kW, 3 kW, and 5 kW, respectively. These findings not only highlight the effectiveness of SCR technology in reducing NOx emissions but also underscore the potential of copper-based Y zeolite catalysts in this regard. The comprehensive characterization of the catalyst provides valuable insights into its structural and chemical properties, paving the way for further advancements in emission control strategies.

Reduction of Emission and Fuel Consumptions based on Mingled Nano Additives in Biodiesel

Using the lipids identified as well as extra residual cooking oil, vegetable, and animal fats, bio-diesel a substitute for fuels derived from petroleum can be produced. Since the 1970s oil crisis, there has been a resurgence of interest in using biodiesel as a fossil fuel substitute due to the fuel's rapidly rising prices, availability uncertainties, and growing environmental and greenhouse gas (GHG) concerns.To produce biodiesel, glycerin and fat or vegetable oil are separated chemically through a process termed transesterification. Glycerin, a valuable byproduct that is typically sold to be used in soaps and other products, and methyl esters, the chemical term for biodiesel, are the two products left over from the process. The industrial term for diesel derived from petroleum, petro diesel, and biodiesel have similar viscosities. Due to the nearly zero sulfur content,it is recommended to be used as an additive in diesel oil formulations to improve the lubricity of pure ultra-low sulfur diesel (ULSD).The current work focuses heavily on reducing emissions and fuel consumption in automobiles. In addition to lowering pollutants and fuel consumption, the transition metal oxide (Copper oxide) additions in nanocrystalline particle form aid in molecular combustion. To create a stable Nano fluid, soap nut biodiesel is combined with metal oxide additive and ultrasonicated. For our experimental investigation, single cylinder, air cooled, constant speed Kirloskar engine is used. The reduction of hydrocarbon (HC), carbon monoxide (CO) and nitrogen oxide (NOx) emissions is investigated. The highest break power of the biodiesel employed in the study is 3.82 KW, greater than the typical diesel's 3.23 KW. The result shows improved engine efficiency, reduced emissions, and better brake thermal efficiency.

Adsorption and Catalytic Reduction of Nitrogen Oxides (NO, N2O) on Disulfide Cluster Complexes of Cobalt and Iron-A Density Functional Study.

The reactivity of nitrogen oxide, NO, as a ligand in complexes with [Fe2-S2] and [Co2-S2] non-planar rhombic cores is examined by density functional theory (DFT). The cobalt-containing nitrosyl complexes are less stable than the iron complexes because the Co-S bonds in the [Co2-S2] core are weakened upon NO coordination. Various positions of NO were examined, including its binding to sulfur centers. The release of NO molecules can be monitored photochemically. The ability of NO to form a (NO)2 dimer provides a favorable route of electrochemical reduction, as protonation significantly stabilizes the dimeric species over the monomers. The quasilinear dimer ONNO, with trans-orientation of oxygen atoms, gains higher stability under protonation and reduction via proton-electron transfer. The first two reduction steps lead to an N2O intermediate, whose reduction is more energy demanding: in the two latter reaction steps the highest energy barrier for Co2S2(CO)6 is 109 kJ mol-1, and for Fe2S2(CO)6, it is 133 kJ mol-1. Again, the presence of favorable light absorption bands allows for a photochemical route to overcome these energy barriers. All elementary steps are exothermic, and the final products are molecular nitrogen and water.