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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.

In this study, material flow analysis (MFA) is applied to quantify and break the obstacles for advancing a circular economy (CE) of platinum (Pt) from catalytic converters (CC) in Europe. First , the value chain and related stakeholders are mapped out in a MFA-like model to both facilitate the assessment of stocks and flows, and get a comprehensive view of potential action levers and resources to close-the-loop. Then, through the cross analysis of numerous data sources, two MFA are completed: (i) one general MFA, and (ii) one sector-specific MFA, drawing a distinction between the fate of Pt from (a) light-duty vehicles, under the ELV Directive 2000/EC/53, and (b) heavy-duty and off-road vehicles. Key findings reveal a leakage of around 15 tons of Pt outside the European market in 2017. Although approximately one quarter of the losses are due to in-use dissipation, 65 % are attributed to insufficient collections and unregulated exports. Comparing the environmental impact between primary and secondary production, it has been estimated that halving the leakages of Pt during usage and collection could prevent the energetic consumption of 1.3x10^3 TJ and the greenhouse gases emission of 2.5x10^2 kt CO2 eq. Through the lens of circularity indicators, activating appropriate action levers to enhance the CE performance of Pt in Europe is of the utmost importance in order to secure future productions of new generations of CC and fuel cells. Moreover, the growing stockpile of Pt from CC in use urges for better collection mechanisms. Also, the CC attrition during use and associated Pt emission s in the environment appears as non-negligible. Based on the scarce and dated publications in this regard, we encourage further research for a sound understanding of this phenomenon that can negatively impact human health.

PurposeImproving human health is a long-lasting endeavour of mankind. In the field of social life cycle assessment (SLCA), the importance of human health is often highlighted, and further development of impact assessment methods has been recommended. The purpose of this article is to present a method for assessing human health impacts within SLCA.MethodsBy using a systematic combining approach, knowledge and experience about assessing human health impacts were obtained from three previously conducted case studies. The first case study was about an airbag system, the second about a catalytic converter and the third about gold jewellery. The disability-adjusted life years (DALY) indicator was used for impact assessment in all three case studies.Results and discussionBoth positive and negative human health impacts associated with the products were identified and assessed in the three case studies. For the airbag system, avoided health impacts in the use phase outweighed health impacts during production. For the catalytic converter, whether health impacts avoided exceeded health impacts caused or not depended on which time perspective regarding impacts was employed. Gold jewellery does not help avoiding any health impacts but caused considerable health impacts when produced at a certain location. Based on experience from these case studies, a generic human health impact assessment method was developed, and a life cycle human health typology for products was developed based on the method. The method provides a basis for analysis and interpretation of health impacts along product life cycles, and it is therefore important to report both positive and negative health impacts separately for different actors.ConclusionsThe developed human health impact assessment method involves the assessment and comparison of both positive and negative human health impacts along product life cycles. In addition to the products assessed in the three case studies, we suggest additional products that could be particularly interesting to assess with the developed method, including medicines, seat belts, other conflict minerals, alcoholic beverages and products with a high chemical impact.

Despite the obvious shift in daily commuting towards electromobility, internal combustion engines (ICEs) still dominate the market, particularly in the transport sector. Their main drawback—cold-start emissions—has driven the development of active control strategies beyond passive exhaust optimizations. An electrically heated catalytic converter (EHC) helps the catalytic converter reach the light-off temperature more quickly through active control; however, it places additional demands on the already strained onboard electrical power distribution network. This paper presents a case study comparing two power supply and control configurations for managing the temperature of the EHC: (i) a smart-switch-based approach using bang-bang control, and (ii) a DC/DC converter with a proportional–integral–derivative (PID) controller. To define key target requirements for a dedicated DC/DC converter suitable for real-world conditions, measurement data such as temperature and electrical power demand were gathered through preliminary pollutant emissions tests performed in a laboratory environment using a programmable bench power supply. For the selected test procedure, engine cold-start emissions using various heater power supply scenarios were reduced by a factor of 6 for Total Hydrocarbons (THC) and by a factor of 5 for Carbon Monoxide (CO). Based on a comparative analysis of power supply parameters, a custom four-leg interleaved Buck converter was developed to meet the target power requirement and to specifically reduce voltage overstress caused by parasitic inductances in the onboard distribution network during rapid load current transients. The efficiency of the proposed DC/DC converter reached 95.8%. Unlike a bang-bang-controlled smart switch, the use of the DC/DC converter reduces both electrical and thermal stress on the vehicle’s cable harness.

Due to the ever-growing challenge of pollutants emitted by vehicles, protection of the environment from the pollutants has become a focus of attention. The rising volume of traffic on our nation's roadways now poses a severe danger to the environment due to hazardous emissions, and the refueling availability and low maintenance of petrol fuel vehicles have prompted many to choose for petrol vehicles. Numerous experts have used a variety of strategies to decrease the amount of emissions produced by vehicles, but this sector still has a great deal of room for advancement. The objective of this work is to compare the emission characteristics of a four-stroke petrol engine with and without a nano zinc oxide (nano-ZnO) encased catalytic converter. The findings indicated that the nano-ZnO coated catalytic converter aided in reducing the CO, CO 2 , HC and NO x emissions by 41.3%, 71.4%, 48.2%, and 46.7%, respectively

This research aims to measure the performance and emission of motorcycle engines using three types of mufflers. Original Equipped manufacturer (OEM), High Performance Low Pollution Muffler (HPLPM), and free flow exhaust were used in this research with various placement distances of the catalytic converter. This research utilized a quantitative method experimental approach. The independent variable used was the placement distance of the copper-based catalytic converter; 65 cm, 75 cm, and 95 cm. The fuel used in the vehicle was gasoline RON 90. Test data was collected at idle, 1000, 3000, and 5000 RPM. Performance testing involved engine rotations ranging from 3500 to 8500 RPM, with increments of 250 RPM and used 1:1 transmission ratio during testing. The results of the testing using the HPLPM exhaust integrated with the catalytic converter showed a reduction in exhaust gas emissions while simultaneously improving engine performance compared to the OEM exhaust. In this study, the catalytic converter installed in HPLPM exhaust positioned at 75 cm resulted in an effective reduction in exhaust gas emissions at each engine rotation, and it also enhanced vehicle performance, achieved the highest torque of 16.14 Nm at an engine rotation of 5500 RPM. As for the highest power, it reached 16.9 HP at an engine rotation of 8500 RPM.

Bulk ceria-zirconia solid solutions (Ce1−xZrxO2−δ, CZO) are highly suited for application as oxygen storage materials in automotive three-way catalytic converters (TWC) due to the high levels of achievable oxygen non-stoichiometry δ. In thin film CZO, the oxygen storage properties are expected to be further enhanced. The present study addresses this aspect. CZO thin films with 0 ≤ x ≤ 1 were investigated. A unique nano-thermogravimetric method for thin films that is based on the resonant nanobalance approach for high-temperature characterization of oxygen non-stoichiometry in CZO was implemented. The high-temperature electrical conductivity and the non-stoichiometry δ of CZO were measured under oxygen partial pressures pO2 in the range of 10−24–0.2 bar. Markedly enhanced reducibility and electronic conductivity of CeO2-ZrO2 as compared to CeO2−δ and ZrO2 were observed. A comparison of temperature- and pO2-dependences of the non-stoichiometry of thin films with literature data for bulk Ce1−xZrxO2−δ shows enhanced reducibility in the former. The maximum conductivity was found for Ce0.8Zr0.2O2−δ, whereas Ce0.5Zr0.5O2-δ showed the highest non-stoichiometry, yielding δ = 0.16 at 900 °C and pO2 of 10−14 bar. The defect interactions in Ce1−xZrxO2−δ are analyzed in the framework of defect models for ceria and zirconia.

Platina play a crucial role in catalytic converter device as one of catalyst that convert toxic gases in the exhaust gas emission to less toxic gas pollutant. The performance of this device can be significantly elevated by implementing platina nanoparticles (Pt NPs) because catalytic performance can be increased by decreasing its particles size. However, nanoparticles are not stable and tend to agglomerate, thus prohibit formation of nano particles. In this context, utilization of cellulose nano crystals (CNCs) in fabrication of Pt NPs are attractive due to their ability to encourage nucleation and prevent agglomeration of nanoparticles. In this study, Pt NPs was prepared by reduction of H2PtCl6 solution at various temperature (25, 33 and 40 °C) with the presence of CNCs. Based on visual observation, darker precipitate was observed by increasing temperature. Further characterization using UV-Vis spectroscopy showed that about 90% of Pt 4 + in solution were successfully convert to dark particles at 40 °C. Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) revealed that the dark particles in sample is Pt NPs with particles size 16.5 ± 3.2 nm.

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.

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 NO x 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. Graphical abstract