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One of the main causes of atmospheric pollution comes from mobile sources that emit noxious gases from internal combustion engines. For the suppression of toxic exhaust gases, a catalytic converter is used as an anti-pollution device, because it catalyzes or accelerates the degradation of emissions making them less harmful. In the catalytic converter, platinum (Pt), palladium (Pd) and rhodium (Rh) catalysts are normally used for their excellent performances. However, these metals are expensive, rare, and scarce in the earth's crust. These precious metals thus emphasized the importance of developing efficient recycling practices. For the recycling of these precious metals, a very fast, easy, economical, environmentally friendly and high-safety electric pulse discharge method was used to separate the Pd and Rh from the spent metal-honeycomb (MH) catalytic converter consisting of p as the catalyst carrier. To standardize the precious metals recycling process and attain the highest level of separation of Pd and Rh, electric pulse shots ranging from 120-240 and standoff distances (gap width between the positive electrode and the sample surface) ranging from 5-10mm were applied. During this process, an electrical explosion occurred within the honeycomb structures through the electric shock. After the electrical explosion, the particles are collected, then sieved and physical characterizations are performed. Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDX) analyses revealed that the most separated particles are highly pure, and dispersed homogeneously without destroying particle structures. In this article, we first report about 87.91% of Pd and 90.77% of Rh are separated from each catalytic converter using the electric pulse discharge method that can overcome challenges and achieve ambitious recycling targets in the recycling industry. The effects of the discharge energies and the shock energy determined by varying electric pulse shots and standoff distance, respectively, are discussed. These findings provide insight into the recovery of precious metals for electric pulse discharge and play a role in developing a very effective recycling method not only for the catalytic converter but also for other devices. [ABSTRACT FROM AUTHOR]

Catalytic converters are part of a vehicle's exhaust system and contain valuable metals (i.e., platinum, palladium, and rhodium). The value of these metals has risen dramatically, and so they have the incidents of theft. This study contributes in two important ways: First, it provides insight into an emerging crime trend of catalsytic converter theft, and second, it advances knowledge of the elasticity of crime, specifically how the value of metal impacts thefts. Data on catalytic converter thefts were collected from official police reports and social media complaints in eight California cities for 42 months. We use regression analysis to study the weekly estimated value of catalytic converters and theft. Our regression approach, which we estimate using feasible generalized least squares, accounts for the non-stationarity in weekly metal thefts and allows for autocorrelation in a panel setting. Findings reveal an average price elasticity of 1.98, meaning that a 10% increase in metal prices results in approximately a 20% increase in catalytic converter thefts. The results illustrate how the value of metals impacts thefts. [ABSTRACT FROM AUTHOR]

This study focuses on the detailed analysis of exhaust emissions from multi-point fuel injection (MPFI) engines by manipulating the injection parameters through a programmable electronic control unit. In addition, tests are carried out using different generations of catalytic converters and checking that their working temperature is correct using a thermographic camera, verifying operation, to evaluate their effect on emission reduction. Detailed comparisons of the results between these configurations will allow the identification of the combination that reduces emissions the most without compromising engine efficiency and performance. This research aims to promote a more sustainable approach in the automotive sector by properly configuring systems, but also by demonstrating the technical robustness of their application in vehicles. It has also helped to verify that varying injection and ignition parameters help to fine-tune fuel injection, resulting in efficient combustion. Combining this variation with catalytic converters has further reduced exhaust pollutants. [ABSTRACT FROM AUTHOR]

The oxidation of carbon monoxide (CO) and unburnt hydrocarbons (HC) under segmented honeycomb catalysts was investigated using actual exhaust gas mixtures from a gasolinefueled internal combustion engine of a motorcycle. The honeycomb catalysts were prepared through a wet process, resulting in four types coated with transition metals (Cu, Cr, Fe, and Ni) supported on Al2O3. The oxidation of CO and HC was monitored using an exhaust gas analyzer across a range of air-to-fuel ratios (AFR), from lean to rich, under stationary conditions. The results demonstrate that the honeycomb catalysts effectively decreased CO and HC concentrations in the exhaust gas. Among the transition metal oxide honeycomb catalysts, Cr and Ni exhibited high CO and HC conversion rates, surpassing those observed with Cu. The average CO and HC conversion calculations, spanning from lean to rich air-tofuel ratios, were consistent with the actual conversion rates achieved. Furthermore, the study investigated the effect of honeycomb segmentation on CO and HC conversion. Surprisingly, the catalytic performance of Cr and Ni remained high even with longer gaps in the honeycomb. Interestingly, the conversion of CO and HC over the iron oxide honeycomb catalyst increased as the gap in the honeycomb became longer. This is likely due to an increase in the gap size and enhanced re-mixing of reactants (CO, HC, and O2) caused by recirculation. Thus, this study provides valuable elucidation on the potential application of segmented honeycomb catalysts for reducing CO and HC emissions in exhaust gases. [ABSTRACT FROM AUTHOR]

The oxidation of carbon monoxide (CO) and unburnt hydrocarbons (HC) under segmented honeycomb catalysts was investigated using actual exhaust gas mixtures from a gasoline-fueled internal combustion engine of a motorcycle. The honeycomb catalysts were prepared through a wet process, resulting in four types coated with transition metals (Cu, Cr, Fe, and Ni) supported on Al2O3. The oxidation of CO and HC was monitored using an exhaust gas analyzer across a range of air-to-fuel ratios (AFR), from lean to rich, under stationary conditions. The results demonstrate that the honeycomb catalysts effectively decreased CO and HC concentrations in the exhaust gas. Among the transition metal oxide honeycomb catalysts, Cr and Ni exhibited high CO and HC conversion rates, surpassing those observed with Cu. The average CO and HC conversion calculations, spanning from lean to rich air-to-fuel ratios, were consistent with the actual conversion rates achieved. Furthermore, the study investigated the effect of honeycomb segmentation on CO and HC conversion. Surprisingly, the catalytic performance of Cr and Ni remained high even with longer gaps in the honeycomb. Interestingly, the conversion of CO and HC over the iron oxide honeycomb catalyst increased as the gap in the honeycomb became longer. This is likely due to an increase in the gap size and enhanced re-mixing of reactants (CO, HC, and O2) caused by recirculation. Thus, this study provides valuable elucidation on the potential application of segmented honeycomb catalysts for reducing CO and HC emissions in exhaust gases.

Platinum group metals (PGMs) assume an important role within the chemistry and chemical engineering due to their exceptional chemical stability in high temperatures and various environmental conditions. Their unique attributes make them highly demanded materials across an array of industries. Nevertheless, the gradual depletion of PGM reserves underscores necessitates of recycling PGM-containing waste as a means to ensure the reasonable utilization of resources. Recycling of catalytic waste, in particular, presents a more cost-effective and environmentally sustainable approach acquiring these metals, in contrast to the conventional practice of mining from natural ores. Of particular importance are spent automotive catalysts, which represent a valuable source of platinum group metals, featuring substantially higher PGM concentrations than their naturally occurring counterparts. Conventionally, the recovering of PGMs from waste materials predominantly employs hydrometallurgical and pyrometallurgical processes. Unfortunately, these established techniques entail the utilization of potent oxidizing acidic solutions, including aqua regia and hydrochloric acid with chlorine gas, which exert adverse ecological consequences. In recent years, there has been a growing focus on the development of alternative methodologies that are both environmentally friendly and economically viable for the recovery of PGMs from spent catalysts. Notable among these emerging techniques are solvometallurgy, molecular recognition technology, and magnetic separation. This comprehensive review endeavors to study and assess the latest advancements in the recovery of platinum group metals from spent catalysts, meticulously evaluating their respective advantages and disadvantages. Through an analysis, this review aspires to identify the most promising method - one that combines environmental friendliness and economic feasibility.

One of the main problems of today’s automotive manufacturers are emission norms that are getting much stricter. According to these high demands, car manufacturers are developing new systems to keep exhaust emissions at the lowest possible level. The resonance expansion system for emissions reduction of internal combustion engines could decrease emissions production not only in modern vehicles but also in older vehicles by additional mounting on the exhaust system. This article shows the resonance expansion system technical solution and simulations of fluid flow done in flow simulation software. The resonance expansion system is also patented, and further experiments for design improvement are planned in the near future.

Despite the current boost in the use of electric vehicles to reduce the automotive sector's footprint, combustion vehicles are and will be present in our cities in both the immediate and long term. In this sense, catalytic converters, which are exhaust gas post-treatment systems for vehicle emission control, are critical for complying with increasingly stringent environmental regulations. This work proposes a systematic review to identify the most relevant knowledge regarding the parameters (materials, geometries, and engine conditions), conditions (cold start, oxygen storage, and deactivation), and mathematical models to consider in the design of catalytic converters. The Scopus database contains 283 records related to this review's objective. After applying the inclusion and exclusion criteria, 65 reports were retrieved for evaluation. A table was created to present the results and prepare this manuscript. The evaluation revealed that the following topics were active: the study of non-noble catalyst materials, as well as new substrate materials and geometries, for designing more compact and cost-effective catalytic converters; the development of strategies to improve conversion during cold starts; and the development of accurate and fast estimation models. [ABSTRACT FROM AUTHOR]

The emission of nitrogen oxide (NOx), nitrogen monoxide (NO) and carbon monoxide (CO) from vehicle exhaust gas generates an adverse effect to the environment as well as the human health. Therefore, the need to reduce such emission is urgent. The decrease of the emission can be achieved through the use of catalytic converter. This study explains the application of catalytic converter prepared from activated carbon to enhance the activity through its adsorption ability. The activated carbon was derived from banana peels after heating them up at 400 ºC for 1.5 hours and activation using natrium hydroxide (NaOH). Several techniques including N2 adsorption-desorption, X-Ray Diffraction (XRD), Scanning Electron Microscopy-Electron Dispersive X-ray (SEM-EDX), and Fourier Transform Infrared (FTIR) were adopted to characterize the activated carbon properties. The activated carbon formed was then coated with copper. The activity of the catalytic converter using activated carbon coated with copper was then tested for its performance on diesel engine Yanmar TF 70 LY-DI with variations in the number of catalyst layers, namely 1 layer (C1), 2 layers (C2) and 3 layers (C3). Sample with three layers (C3) of catalyst exhibited the highest activity with the percentage efficiency in reducing emissions concentration of 48.76 %; 31.27 % and 29.35 % for NOx, NO and CO, respectively.

This study focuses on the detailed analysis of exhaust emissions from multi-point fuel injection (MPFI) engines by manipulating the injection parameters through a programmable electronic control unit. In addition, tests are carried out using different generations of catalytic converters and checking that their working temperature is correct using a thermographic camera, verifying operation, to evaluate their effect on emission reduction. Detailed comparisons of the results between these configurations will allow the identification of the combination that reduces emissions the most without compromising engine efficiency and performance. This research aims to promote a more sustainable approach in the automotive sector by properly configuring systems, but also by demonstrating the technical robustness of their application in vehicles. It has also helped to verify that varying injection and ignition parameters help to fine-tune fuel injection, resulting in efficient combustion. Combining this variation with catalytic converters has further reduced exhaust pollutants.

In this study, a modified catalytic converter was employed to treat the harmful exhaust gas pollutants of a twin-cylinder, four-stroke spark-ignition engine. This research mainly focuses on the emission reduction of unburnt hydrocarbons, carbon monoxide, and nitrogen oxides at low light-off temperatures. A sucrolite catalyst (sucrolite) was coated over the metallic substrate present inside the catalytic converter, and exhaust gas was allowed to pass through it. A scanning electron microscope, X-ray diffraction, and Fourier transform infrared spectroscopy were used to investigate the changes in morphology, chemical compounds, and functional group elements caused by the reactions. Catalytic reactions were studied by varying the engine loads and bed temperatures, and the results were compared with those of the commercial catalytic converter. The results show that sucrose present in the catalyst was suitable at low temperatures while alumina was suitable for a wide range of temperatures. In the case of the modified catalytic converter, the maximum catalytic conversion efficiencies achieved for oxidizing CO and HC were 70.73% and 85.14%, respectively, and for reduction reaction at NOx was 60.22% which is around 42% higher than in commercial catalytic converter. As a result, this study claims that sucrolite catalyst is effective for low-temperature exhaust gas. [ABSTRACT FROM AUTHOR]

Air pollution caused by cars is a major contributor to the greenhouse effect, making it an issue of widespread concern. End-of-combustion of an engine produces pollutants such carbon monoxide (CO), oxides of nitrogen (NOx), oxides of sulphur (SOx), particulate particles and unburned hydrocarbons (HC). The environment, air quality, and human health are all negatively affected by these contaminants. A catalytic converter is a pollution control device for every fuel-operated automobile exhaust system. Increasingly low emission standards and automobile space constraints necessitate optimizing the device geometry. The uniformity index parameter mainly judges a catalytic converter's smooth working and operational life. In the present study, 16 catalytic converter geometry designs are investigated. Their effects on exhaust flow distribution, i.e., uniformity index, pressure drop, and peak pressure at monolith substrate entry, are identified and visualized through contour plots. A finite volume approach is used to study hydraulic diffusion inside the device with the help of the ANSYS Fluent CFD package. Two-dimensional axisymmetric CFD simulations identify optimum design parameters among the considered geometries. The design of diffuser geometry is crucial in maintaining a uniform flow across monolith honeycomb structures. [ABSTRACT FROM AUTHOR]

The utilization of catalytic converters is one of the well-known strategies to clean the exhaust. The catalytic converters oxidize the destructive carbon monoxide and hydrocarbon emissions into harmless CO2 and water vapor. In this experiment, the essential objective is to develop a catalytic converter with combined methods like selective catalytic reduction, NOx storage and reduction (SCR-NSR) procedure and test its effectiveness in the NOx reduction from the exhaust of diesel engine. The combination of the SCR-NSR catalytic systems is proposed in this experimentation for building up an effective catalytic converter and distinguishing the optimal emission processes. The fabricated SCR-NSR catalytic converter is fitted to the exhaust system and the emission rates are estimated with the help of a gas analyzer. The testing is done by utilizing diesel as fuel in the Kirloskar TV1 engine with NSR, non-filter, and combined NSR–SCR system. The investigation is experienced for 20 trials with different emission parameters analyzed. For improving the discharge level in the engine, the test data are predicted with the proposed numerical model and tested in Mat Lab software. The invasive weed optimization and particle swarm optimization together with a recurrent neural network are utilized for the prediction and optimization process and parameters like compression ratio, input power, and load are utilized as input to the experimentation. In the 20 trials, a low level of discharge is attained in the 17th trial. Subsequently, the prediction goes for the 20 sets individually and compared with the 17th set and the experimental results demonstrate that the discharge rates acquired for consolidated NSR–SCR were observed to be 0.01% of CO, 3% of HC, 0.1% of CO2, 20.74% of O2, and 68 ppm of NOx. The point when compared to predicted outcomes demonstrates the ideal level of 0.001% of CO, 0.5% of HC, 0% of CO2, 21.76% of O2, and 60.6 ppm of NOx, respectively. The proposed invasive weed optimization and particle swarm optimization obviously reduce the emission rates of diesel engines more than the other comparative methods. [ABSTRACT FROM AUTHOR]

One of the main problems of today's automotive manufacturers are emission norms that are getting much stricter. According to these high demands, car manufacturers are developing new systems to keep exhaust emissions at the lowest possible level. The resonance expansion system for emissions reduction of internal combustion engines could decrease emissions production not only in modern vehicles but also in older vehicles by additional mounting on the exhaust system. This article shows the resonance expansion system technical solution and simulations of fluid flow done in flow simulation software. The resonance expansion system is also patented, and further experiments for design improvement are planned in the near future. [ABSTRACT FROM AUTHOR]

A quick overview of the increasing pollutants worldwide shows a parallel movement toward strict legalization to limit contamination of air before it gets out of hand, however, in this paper, we are discussing a source of emissions that is yet to receive its' deserved attention rendered in non-road mobile machinery. Our proposal to solve this issue unfolds by delivering an efficient catalyst, starting by characterizing its relevant properties such as the choice of material, the shape of the catalyst, the chemical structure, and the active coating agent. So, in this sequence of experiments, we are investigating the performance of five ceramic supports impregnated with 0.1 and 0.2 wt% palladium (II). Starting by testing the samples' ability to oxidize CO in a fixed bed reactor, we will measure their performance in converting flue-gas emissions by testing the samples on a custom-designed catalytic converter connected to a dynamometer system. Following this study, we can achieve an outstanding 98% reduction in NOx and 95% reduction in CO and build a direct relation between sample properties and performance. For now, this research will be the first part of a tailored proposed solution to reduce NRMM emissions using a catalytic converter where this paper will mostly be concerned with the overall performance of the catalyst. [ABSTRACT FROM AUTHOR]

The motorcycles are unignorable near-ground pollutant emission sources that increase the human exposure in the dense area. However, the information of the polycyclic aromatic hydrocarbons (PAHs) emissions under different scenarios of engine and emission control for motorcycle is limited. This study focused on the PAH emissions from two fuel-injection types of motorcycles, including the premixed fuel-injection (PFi) with carburetor and electronic fuel-injection (EFi). Specifically, the effects of throttle opening (TO), secondary air system (SAS), oxygen sensor (OS), oxidation catalytic converter (OCC), and three-way catalytic converter (TWC) on PAH emissions are investigated. Results show that the PAH emission concentrations increase 227–727%, 351–492%, and 155–408% by the increasing TO ratio, unworking SAS, and OS units in both motorcycles. For the PFi engine, the OCC unit is found to be more effective in PAH control (31–89%) than the SAS system (72–80%), especially under low TO operation. For the EFi engine which dominates the motorcycle market recently, the oxygen sensor for more accurate combustion control shows a better PAH reduction (36–76%) than TWC system (21–66%). The ultra-fine particulate phase PAHs, which is hardly removed by catalyst, needs to be further considered. Moreover, the total PAH emission level of the EFi engine is still about ten times higher than that of the PFi. By the annual emission calculation for three densely populated countries, the recent evolution significantly reduces the annual hydrocarbon (HC), carbon monoxide (CO), and nitrogen oxide (NOx) emissions but have unignorable PAH emissions. These emissions continuously affect the human health in the near-ground urban air and need to be considered in the next generation of motorcycle design. [ABSTRACT FROM AUTHOR]

The emission of nitrogen oxide (NOx), nitrogen monoxide (NO) and carbon monoxide (CO) from vehicle exhaust gas generates an adverse effect to the environment as well as the human health. Therefore, the need to reduce such emission is urgent. The decrease of the emission can be achieved through the use of catalytic converter. This study explains the application of catalytic converter prepared from activated carbon to enhance the activity through its adsorption ability. The activated carbon was derived from banana peels after heating them up at 400 ºC for 1.5 hours and activation using natrium hydroxide (NaOH). Several techniques including N2 adsorption-desorption, X-Ray Diffraction (XRD), Scanning Electron Microscopy-Electron Dispersive X-ray (SEM-EDX), and Fourier Transform Infrared (FTIR) were adopted to characterize the activated carbon properties. The activated carbon formed was then coated with copper. The activity of the catalytic converter using activated carbon coated with copper was then tested for its performance on diesel engine Yanmar TF 70 LY-DI with variations in the number of catalyst layers, namely 1 layer (C1), 2 layers (C2) and 3 layers (C3). Sample with three layers (C3) of catalyst exhibited the highest activity with the percentage efficiency in reducing emissions concentration of 48.76 %; 31.27 % and 29.35 % for NOx, NO and CO, respectively. [ABSTRACT FROM AUTHOR]

Copyright of Media Mesin: Majalah Teknik Mesin is the property of Media Mesin: Majalah Teknik Mesin and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study presents synthesis results of catalysts made of perovskite-like oxide La2-xSrxCuO4 (x=0.0, 0.5, 1.0) using the citrate method and crystallisation at 800°C. The structure of the catalysts was characterised by X-ray diffraction (XRD). The perovskite- like oxide catalyst activity was enhanced with gold (Au) and platinum (Pt). Au was mounted on the perovskite-like oxide catalysts by the sol-gel method. The activity of the perovskite-like oxide La2-xSrxCuO4 (x=0.0, 0.5, 1.0) and the perovskite catalyst LaMnO3/ LaCuO3 was evaluated by complete oxidation of volatile hydrocarbons (HCs) in a mixture of toluene and methyl ethyl ketone (MEK) and carbon monoxide (CO) in a microflow analysis system combined with gas chromatography. The results showed that the light-off temperature (the 50% conversion temperature of the catalysts) of the Pt, Au/perovskite catalyst samples decreased significantly. The light-off temperature of the Au/LaSrCuO4 Au nanoparticle catalysts in the complete CO oxidation reaction reached a temperature of 150°C, lower than the Pt/LaSrCuO4 catalyst (170°C), allowing replacement of previous Pt catalysts with Au nanoparticle catalysts. The LaSrCuO4 catalyst had better oxidising activities than the La2CuO4 catalyst, indicating that the addition of strontium (Sr) has increased the catalyst activity, and demonstrates the potential for application in catalytic converters in motorcycles.

Air pollution caused by cars is a major contributor to the greenhouse effect, making it an issue of widespread concern. End-of-combustion of an engine produces pollutants such carbon monoxide (CO), oxides of nitrogen (NOx), oxides of sulphur (SOx), particulate particles and unburned hydrocarbons (HC). The environment, air quality, and human health are all negatively affected by these contaminants. A catalytic converter is a pollution control device for every fuel-operated automobile exhaust system. Increasingly low emission standards and automobile space constraints necessitate optimizing the device geometry. The uniformity index parameter mainly judges a catalytic converter’s smooth working and operational life. In the present study, 16 catalytic converter geometry designs are investigated. Their effects on exhaust flow distribution, i.e., uniformity index, pressure drop, and peak pressure at monolith substrate entry, are identified and visualized through contour plots. A finite volume approach is used to study hydraulic diffusion inside the device with the help of the ANSYS Fluent CFD package. Two-dimensional axisymmetric CFD simulations identify optimum design parameters among the considered geometries. The design of diffuser geometry is crucial in maintaining a uniform flow across monolith honeycomb structures.

The phenomenon of environmental pollution in the machinery system is problem that often occurs. One of them is the emission from burning fossil fuels of diesel engines. Therefore, it is necessary to do proper handling to reduce the emission content of diesel engines, one of which is by using catalytic converter engineering technology. In this study, the catalytic converter was made using an activated carbon filter from banana peel waste with sodium hydroxide (NaOH) activator. The activated carbon formed is then mixed with nickel oxide powder to be used as catalyst and white cement as binder. Diesel engine emission testing is carried out with time variations from 3 to 12 minutes. The results show that there is decrease in the content of carbon monoxide (CO) obtained by 57% when testing emissions at minute 12. While for the content of NOx and NO there is decrease of 43%. This indicates that the mixture of activated carbon from banana peel waste and nickel oxide powder is very effective in reducing the content of diesel engine exhaust emissions.

Despite the current boost in the use of electric vehicles to reduce the automotive sector’s footprint, combustion vehicles are and will be present in our cities in both the immediate and long term. In this sense, catalytic converters, which are exhaust gas post-treatment systems for vehicle emission control, are critical for complying with increasingly stringent environmental regulations. This work proposes a systematic review to identify the most relevant knowledge regarding the parameters (materials, geometries, and engine conditions), conditions (cold start, oxygen storage, and deactivation), and mathematical models to consider in the design of catalytic converters. The Scopus database contains 283 records related to this review’s objective. After applying the inclusion and exclusion criteria, 65 reports were retrieved for evaluation. A table was created to present the results and prepare this manuscript. The evaluation revealed that the following topics were active: the study of non-noble catalyst materials, as well as new substrate materials and geometries, for designing more compact and cost-effective catalytic converters; the development of strategies to improve conversion during cold starts; and the development of accurate and fast estimation models.

The present study is an integrated approach to the Pt, Pd, and Rh cycling derived from catalytic converters along highway roadsides of the Athens Basin, including their contents, the dispersed Pt- and Pd-bearing nano- and microparticles in dust and bioaccumulation in plants, aiming to assess the auto-catalyst-derived environmental impact to the large city of Athens and the potential human health risk. The determined mean values of 314 Pt, 510 Pd, and 23 Rh (all in μg/kg) in dust samples are much lower than the 2070 μg/kg Pt and 1985 μg/kg Pd contents in gully pots in the Katechaki peripheral highway and higher than the mean values of 230 Pt, 300 Pd, and 13 Rh (all in μg/kg) in the soil samples. With the exception of two samples from gully pots, from 51% to 70% of the samples (for the Pd and Pt, respectively) fall in the range from 100 to 400 μg/kg. The calculated accumulation factors showed means of 3.88 μg/kg Pd and 2.95 μg/kg Pt for plants and tree leaves, but any significant difference (t-test) is lacking, and they are much lower than those reported for roots of plants (literature data). Although the Pt, Pd, and Rh bioaccumulation factors for shoots of plants/crops are relatively low, the increasing number of cars with catalytic converters in Greece and the relatively high bioaccumulation in the food chain may highlight a potential risk for human health and ecosystems, and the need for special attention on their bioaccumulation and bioaccessibility on a global scale. [ABSTRACT FROM AUTHOR]

Catalytic converters (automotive catalysts) and the chemical reactions they catalyze appear in general and introductory chemistry textbooks. Although the detailed mechanisms of the chemical reactions that occur in catalytic converters have been clearly revealed via recent developments in surface and computational chemistry research, the description and illustration of the catalysis are still ambiguous in textbooks. In this paper, we describe an extracurricular lecture whereby a handmade teaching aid was employed to illustrate the basic principle of the catalytic oxidation of carbon monoxide over platinum surface, which is an essential reaction occurring in catalytic converters. The teaching aid, constructed combining easily available materials, can illustrate the positions and motions of the molecules on the platinum surface during catalytic oxidation. The lecture was favorably received by non-chemistry majors and high school students. Despite the difficulty of the topic, the audience displayed a relatively high level of understanding.

A modified Scheffe's simplex lattice design method is proposed to study the properties of multicomponent materials. This modified Scheffe's method allowed determining the optimal compositions of cordierite and corundum based ceramic materials that are used as catalyst carrier for gas purification equipment. The obtained material (0.63-1.25 mm weight fraction of cordierite of 0.35 mass% fraction; < 0.63 mm weight fraction of cordierite of 0.35 mass% fraction; < 0.06 mm weight fraction of corundum of 0.2 mass% fraction; 1.25-2.5 mm weight fraction of cordierite of 0.2 mass% fraction) was used successfully for the manufacturing of catalytic neutralizers of gas emissions.

Copyright of Journal of Polytechnic is the property of Journal of Polytechnic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper uses computational simulation to compare the performance of two catalytic systems designed for the removal of oxides of nitrogen from automotive engine exhaust using selective catalytic reduction (SCR). The first system is comprised of an SCR catalyst alone, whilst the second system adds an ammonia slip catalyst (ASC) to the end of an SCR catalyst. Both systems had the same total length. Comparisons of the NOx removal efficiency and the degree of ammonia slip are made using driving cycles and an optimized ammonia dosing strategy. Comparisons are also made for the case where a constant error in the ammonia dosing occurs. The addition of the ASC reduces ammonia slip during over‐dosing scenarios and gives a greater NOx conversion during under‐dosing cases. This work concludes that the ASC is a positive addition to the SCR in meeting the exhaust emission regulations. Although it does not necessarily allow for a higher NOx conversion, its ability to cope with under‐ and over‐dosing situations can be beneficial in catalyst aging and unpredictable driving conditions. [ABSTRACT FROM AUTHOR]

In the present work, heat transfer and fluid flow and their effects on entropy generation in a realistic catalytic converter of a Lada Niva 21214 vehicle are studied using large eddy simulation. At first, the pressure drop over the catalytic converter is measured for dry air at constant temperature ( T = 298 K), different volumetric flow rates, and extrapolated to large volumetric flow rates for dry air ( T = 298 K) and for the exhaust gas under realistic engine conditions ( T = 900 K) using the Darcy–Forchheimer relation. Then, coupled heat and fluid flow phenomena inside the catalytic converter are analyzed for nonreacting isothermal conditions and nonreacting conditions with conjugate heat transfer by using the large-eddy simulation. The predicted pressure drop agrees well with the measured and extrapolated data. Based on the obtained numerical results, the characteristic flow features are identified, namely: the impinging flow with stagnation, recirculation, flow separation and laminarization within the fine ducts of the monolith, which depends on the heat transfer through temperature-dependent thermophysical properties of exhaust gas. Moreover, due to high-velocity gradients at the wall of the narrow ducts in the monolith, entropy production by viscous dissipation is observed predominantly in the monolith region. In contrast, entropy production due to heat transport is relatively small in the monolith region, while it overwhelms viscous dissipation effects in the pipe regions. [ABSTRACT FROM AUTHOR]

The increasing number of motorized vehicles has a direct impact on exhaust gas air pollution. The air pollution in urban areas is dominated by motorized vehicle emissions, along with pollution problems. This study aims to reduce motor vehicle emissions by using a catalytic converter design made from a brass plate catalyst in the shape of a honeycomb. Honeycomb-shaped brass is suitable for catalysts in the catalytic converter. Besides being easy to obtain and cheap in price, the catalyst can reduce and oxidize exhaust gases well, making it suitable as a catalyst material. The method used in this research is the experimental method. It is started from the design of the catalytic converter house and determining the type of catalyst to the process of making the catalytic converter with a honeycomb-shaped brass plate. Then, testing to determine the emission of exhaust gases produced is required. The last step is to compare it without using a catalytic converter or standard conditions. From the results of the emission test, it was found that the use of a catalytic converter made from a brass plate catalyst in the shape of a honeycomb can reduce HC and CO emissions, while CO2 emissions have increased. A decrease in HC gas emissions by 19.1% for a single catalytic converter and 33.7% for a dual catalytic converter is better compared to without using a catalytic converter or standard conditions. Reduced CO gas emissions by 23.8% for a single catalytic converter and 43.1% for a dual catalytic converter are compared to without using a catalytic converter. Meanwhile, CO2 gas emissions increased by 60.7% for a single catalytic converter, and 81.6% for multiple catalytic converters are compared without using a catalytic converter. This is a result of the addition of oxygen to the oxidation process that running smoothly.

The main objective of this study is to develop a neural network model to predict high-accuracy responses and optimize the input parameters using response surface methodology to improve catalytic converter performance when powered by diisopropyl ether/gasoline blends. The engine exhaust gas was treated by a commercial catalytic converter by varying the brake power, engine speed, and compression ratio, and the pollutant levels were measured. Again, the experiment was repeated, and the exhaust gas was treated by a sucrose/alumina catalyst-coated converter and the results were compared. Experimentally obtained data were employed to develop a neural network and response surface methodology model. The developed artificial neural network yielded higher R2 values of over 0.9977 for commercial catalytic converter and over 0.99633 for sucrose/alumina catalyst-coated converter. Furthermore, mean square error values were less than 3 % for all the responses which indicates higher prediction accuracy. Similarly, the developed response surface methodology model exhibited a higher F-value and lower p-value which indicates the model is accurate. Moreover, the desirability factor of over 0.99 for both cases shows the model's high stability. The predicted optimum brake power of 8.01 kW at 2500 rpm and 9.5 compression ratio produced lesser emissions and the validation test error was found to be less than 4 %. Thus, the authors conclude that the combined application of artificial neural network and response surface methodology will be efficient in exhaust gas pollution level prediction and optimization. • Synthesis of a novel catalyst coating to the catalytic converter. • Conversion performance of the sucrolite catalytic convertor is investigated. • The sucrolite catalytic convertor also represents an active phase for CO oxidation when deposited on the catalyst surfaces. • Combined results of RSM and ANN are used for prediction and validation. [ABSTRACT FROM AUTHOR]

The most applicable ICE monitoring method is selective control followed by individual corrections for the current technical condition. The combination of a gas analyzer installed individually in each collector, a motor tester, and a loader which provides test modes makes it possible to recognize failures of exhaust and other systems with high accuracy and to assign an individual corrective action to ensure specified environmental and economic parameters. We developed a generalized mathematical model of changes in the composition of exhaust gases depending on changes in the resistance of the catalytic converter, the spark gap of the spark plug, and the capacity of the electromagnetic nozzle.

The Thermal Energy Storage (TES) System aids in improving the cold start efficiency of the catalytic converter (CC). To further improve the TES and CC performance, loop heat pipes embedded into the PCM, TES unit are presented. For evaluation, three cases are considered: Case 1; CC without TES, Case 2; CC with TES, Case 3; CC with a heat pipe embedded in PCM TES. Mg70Zn24.9Al5.1 is used as PCM and paraffin oil as the working fluid for the heat pipe. Three 30 minute transient cycles with idle events in between were run, with the engine soaking for 30 minutes at ambient conditions with varied loads (0 to 100%) at 2000 rpm. Heat storage and release cycles were run for each load condition. Average warm-up HC, NOx and CO conversion efficiency improvement of 45–85% with Case 3, 35–62% with Case 2 compared to Case 1 were observed. Heat storage time was observed to be lower by ~ 35% for Case 3 while the heat retention time was observed to be better for Case 2 by ~44%. System efficiency and effectiveness were found to be better up to 14% and ~0.2 with Case 3 compared to Case 2. Overall Case 3 showed better performance with some penalty on the heat retention time compared Case 2. [ABSTRACT FROM AUTHOR]

Catalytic converter is an after-treatment technique used to control the emissions in internal combustion (IC) engines. Fly ash produced in the thermal power plant causes substantial environmental problems. In this study, waste fly ash is used as a suitable catalytic material in the catalytic converter for reducing hydrocarbon (HC) and carbon monoxide (CO) emissions from the diesel engine powered with the plastic oil blend (50% Diesel + 50% Plastic Oil). The fly ash was molded into solid for the catalytic converter by treatment with dilute sulfuric acid (H2SO4). The experimental investigations were done with and without the prepared catalytic converter system at the exhaust with various engine loads (0, 1.3, 2.6, 3.9 and 5.2 kW). HC and CO emissions significantly reduced by 12.9% and 25%, respectively, at the full load conditions under the usage of the fly ash-based catalytic converter. This established the suitability of the waste fly ash as a potential catalyst material in the catalytic converter for IC engines. Here, both the fuel used and the catalytic material were produced from waste products, which is found to be very cost effective and also leading to sustainability. [ABSTRACT FROM AUTHOR]

The discharge of harmful impurities put into air which creates unwanted effects to the environments and people. Inadequate engine combustion is one of the causes for air pollution with the emission of CO, HC, NOx, SOx soon. Whenever there is an incomplete combustion takes place huge volume of CO gas is released. If the fuel includes a high Sulphur concentration, the Sulphur in the petroleum combines with the oxygen during the combustion process and releases SO2. The unburnt hydrocarbon is due to incomplete combustion and NOx (Oxides of Nitrogen) are leads to the formation of uninflamed gas in the exhaust with nitrogen. Hence, rigid norms of effluence emissions are enforced as safety measures which has made exhaust gas aftertreatment systems important. In order to reduce the engineemission, the current method is the use of catalytic converter. This paper discusses an effective system for improving presentation of the catalytic converter by using an embedded controller in proportion with emission. [ABSTRACT FROM AUTHOR]

Improving the flow field uniformity of catalytic converter can promote the catalytic conversion of NO to NO2. Firstly, the physical and mathematical models of improved catalytic converter are established, and its accuracy is verified by experiments. Then, the NO catalytic performances of standard and improved catalytic converters are compared, and the influences of structural parameters on its performance are investigated. The results showed that: (1) The gas uniformity, pressure, drop and NO conversion rate of the improved catalytic converter are increased by 0.0643, 6.78%, and 7.0% respectively. (2) As the cell density combination is 700 cpsi/600 cpsi, NO conversion rate reaches the highest, 73.7%, and the gas uniformity is 0.9821. (3) When the tapered height is 20 mm, NO conversion rate reaches the highest, 72.4%, and the gas uniformity is 0.9744. (4) When the high cell density radius is 20 mm, NO conversion rate reaches the highest, 72.1%, and the gas uniformity is 0.9783. (5) When the tapered end face radius is 20 mm, NO conversion rate reaches the highest, 72.0%, and the gas uniformity is 0.9784. The results will provide a very important reference value for improving NO catalytic and reducing vehicle emission. [ABSTRACT FROM AUTHOR]