Functions of Rare Earth Metals in Automobile Emission Purification Catalysts

The functions of rare earth metals in the automobile emission purification catalysts were reviewed, and it was clarified that with precious metals resources using up gradually emission regulations becoming more and more strict, rare earth metals will play more and more important roles in the high performance, and in low price automobile emission purification catalysts, they can not be substituted by other elements, for example, precious metals.

Magnetic properties and heavy metal contents of automobile emission particulates

Measurements of the magnetic properties and total contents of Cu, Cd, Pb and Fe in 30 automobile emission particulate samples indicated the presence of magnetic particles in them. The values of frequency dependent susceptibility （Xfd） showed the absence of superparamagnetic （SP） grains in the samples. The IRM20mT （isothermal remanent magnetization at 20 mT） being linearly proportional to SIRM （saturation isothermal remanent magnetization） （R^2=0.901）, suggested that ferrimagnetic minerals were responsible for the magnetic properties of automobile emission particulates. The average contents of Cu, Cd, Pb and Fe in automobile emission particulates were 95.83, 22.14, 30.58 and 34727.31 mg/kg, respectively. Significant positive correlations exist between the magnetic parameters and the contents ofPb, Cu and Fe. The magnetic parameters of automobile emission particulates reflecting concentration of magnetic particles increased linearly with increase of Pb and Cu content, showed that the magnetic measurement could be used as a preliminary index for detection of Pb and Cu pollution.

Separation of Pd and Pt from highly acidic leach liquor of spent automobile catalysts with monothio-Cyanex 272 and trioctylamine

Platinum group metals(PGMs),especially Pd,Pt,and Rh,have drawn great attention due to their unique features.Direct separation of Pd and Pt from highly acidic automobile catalyst leach liquors is disturbed by various factors.This work investigates the effect of various parameters including the acidity,extractant concentration,phase ratio A/O,and diluents on the Pd and Pt extraction and their stripping behaviors.The results show that the Pd and Pt are successfully separated from simulated leach liquor of spent automobile catalysts with monothioCyanex 272 and trioctylamine(TOA).Monothio-Cyanex 272 shows strong extractability and specific selectivity for Pd,and only one single stage is needed to recover more than 99.9% of Pd,leaving behind all the Pt,Rh,and base metals of Fe,Mg,Ce,Ni,Cu,and Co in the raffinate.The loaded Pd is efficiently stripped by acidic thiourea solutions.TOA shows strong extractability for Pt and Fe at acidity of 6 mol·L^(–1) HCl.More than 99.9% of Pt and all of the Fe are extracted into the organic phase after two stages of countercurrent extraction.Diluted HCl easily scrubs the loaded base metals(Fe,Cu,and Co).The loaded Pt is efficiently stripped by 1.0 mol·L^(–1) thiourea and 0.05–0.1 mol·L^(–1) Na OH solutions.Monothio-Cyanex 272 and TOA can realize the separation of Pd and Pt from highly acidic leach liquor of spent automobile catalysts.

Regulated and Speciated Hydrocarbon Emissions from a Dual Fuel Light Duty Vehicle with and Without a Three-Way Catalyst

The regulated pollutants （CO,HC and NOx） and unregulated pollutants （volatile organic compounds and carbonyl compounds）,emitted from a dual fuel vehicle fueled with gasoline and E10 fuel,are measured under a transient cycle and steady modes.The impacts of a three-way catalyst （TWC） are investigated for the two types of fuels.The measured results show that NOx and acetaldehyde emitted from the E10-fueled car are much more than that from the gasoline-fueled car under the same modes.On the basis of maximum incremental reactivity （MIR） factors and emissions of organic gases,the ozone specific reactivity of the tailpipe gases are evaluated.

Novel Oxygen Storage Components Promoted Palladium Catalysts for Emission Control in Natural Gas Powered Engines

A three-way catalyst comprised novel oxygen storage components for emission control in natural gas powered engines was prepared. The addition of novel oxygen storage components to the Pd/γ-Al2O3 catalysts resulted in improved activities of the fresh and aged catalyst by lowering the light-off temperature for methane in natural gas engines exhaust.

Optimization of microwave heating thickness for spent automobile catalyst

A new method was developed to optimize the microwave heating thickness of the spent automobile catalyst in order to improve the uniform distribution of the temperature field. The average penetration depth and the microwave heating thickness of the spent automobile catalyst were calculated by Gauss model and numerical calculation based on dielectric loss tangent and reflection loss. The results showed that the spent automobile catalyst was a medium loss material. The average penetration depth was 1.11 m from room temperature to 800 ℃. The optimum microwave heating thickness of the spent automobile catalyst was about 0.83 m or 0.75 times of the average penetration depth. Industrial application analysis indicated that the optimization of heating thickness could improve the uniform distribution of the temperature field and reduce energy consumption.

No-catalyst growth of vertically-aligned AlN nanocone field electron emitter arrays with high emission performance at low temperature

The A1N nanostructures with a wide band-gap of 6.28 eV are considered as ideal cold cathode materials because of their low electron-affinity. Many methods have been devoted to fabricating A1N nanostructures, but high growth temperature over 800℃ and the use of the catalysts in most methods limit their practical application and result in their poor field-emission behaviours in uniformity. This paper reports that without any catalysts, a simple chemical vapour deposition method is used to synthesize aligned A1N nanocone arrays at 550℃ on silicon substrate or indium tin oxide glass. Field emission measurements show that these nanocones prepared at low temperature have an average turn-on field of 6 V/μm and a threshold field of 11.7 V/μm as well as stable emission behaviours at high field, which suggests that they have promising applications in field emission area.

Application of hopcalite catalyst for controlling carbon monoxide emission at cold-start emission conditions

Carbon monoxide(CO) is a poisonous gas particularly to all leaving being present in the atmosphere.An estimate has shown that the vehicular exhaust contributes the largest source of CO pollution in developed countries.Due to the exponentially increasing number of automobile vehicles on roads,CO concentrations have reached an alarming level in urban areas.To control this vehicular exhaust pollution,the end-of-pipe-technology using catalytic converters is recommended.The catalysts operating efficiently in a catalytic converter are a challenging class of materials for applications in cold start of engines to maintain indoor air quality.In the cold start period,the catalytic converter was entirely inactive,because the catalytic converter had not been warmed up.The cold start phase is also depending upon the characteristics of vehicles and property of catalysts.The increasing cost of noble metals with the increasing number of vehicles motivates the investigation of material concepts to reduce the precious metal content in automotive catalysts or to find a substitute for noble metals.Hopcalite(CuMnOx) catalyst could work very well at the low temperature;thus,it can overcome the problem of cold-start emissions if used in a catalytic converter.Further,low cost,easy availability and advanced synthesis methods with stabilizer,promoter,etc.,advocates for the use of hopcalite as an auto exhaust purification catalyst.Although there are numerous research articles present on this topic until now,no review has been presented for demanding this issue.So there is a space in this area,and it has been made an attempt to seal this hole and progress the future scope for hopcalite catalyst for purification of exhaust gases by this review.

Assessments on emergy and greenhouse gas emissions of internal combustion engine automobiles and electric automobiles in the USA

Increasing energy consumption in the transportation sector results in challenging greenhouse gas(GHG)emissions and environmental problems.This paper involved integrated assessments on GHG emissions and emergy of the life cycle for the internal combustion engine(ICE)and electric automobiles in the USA over the entire assumed fifteen-year lifetime.The hotspots of GHG emissions as well as emergy indices for the major processes of automobile life cycle within the defined system boundaries have been investigated.The potential strategies for reducing GHG emissions and emergy in the life cycle of both ICE and electric automobiles were further proposed.Based on the current results,the total GHG emissions from the life cycle of ICE automobiles are 4.48 E+07 kg CO2-e which is320 times higher than that of the electric automobiles.The hotspot area of the GHG emissions from ICE and electric automobiles are operation phase and manufacturing process,respectively.Interesting results were observed that comparable total emergy of the ICE automobiles and electric automobiles have been calculated which were 1.54 E+17 and 2.20 E+17 sej,respectively.Analysis on emergy index evidenced a better environmental sustainability of electric automobiles than ICE automobiles over the life cycle due to its higher ESI.To the authors’knowledge,it is the first time to integrate the analysis of GHG emissions together with emergy in industrial area of automobile engineering.It is expected that the integration of emergy and GHG emissions analysis may provide a comprehensive perspective on eco-industrial sustainability of automobile engineering.

Impact of diesel emission fluid soaking on the performance of Cu-zeolite catalysts for diesel NH3-SCR systems

Diesel emission fluid （DEF） soaking and urea deposits on selective catalytic reduction （SCR） catalysts are critical issues for real diesel engine NH3-SCR systems. To investigate the impact of DEF soaking and urea deposits on SCR catalyst performance, fresh Cu-zeolite catalyst samples were drilled from a full-size SCR catalyst. Those samples were impregnated with DEF solutions and subsequently hydrothermally treated to simulate DEF soaking and urea deposits on real SCR catalysts during diesel engine operations. Their SCR performance was then evaluated in a flow reactor with a four-step test protocol. Test results show that the DEF soaking leached some Cu from the SCR catalysts and slightly reduced their Cu loadings. The loss of Cu and associated metal sites on the catalysts weakened their catalytic oxidation abilities and caused lower NO/NI-I3 oxidation and lower high-temperature N20 selectivity. Lower Cu loading also made the catalysts less active to the decomposition of surface ammonium nitrates and decreased low-temperature N20 selectivity. Cu loss during DEF impregnation released more acid sites on the surface of the catalysts and increased their acidities, and more NH3 was able to be adsorbed and involved in SCR reactions at medium and high temperatures. Due to lower NH3 oxidation and higher NH3 storage, the DEF-impregnated SCR catalyst samples showed higher NOx conversion above 400 ℃ compared with the non-soaked one. The negative impact of urea deposits during DEF impregnation was not clearly observed, because the high-temperature hydrothermal treatment helped to remove the urea deposits.

Optimization of Cutting Parameters for Trade-off Among Carbon Emissions, Surface Roughness, and Processing Time

As the manufacturing industry is facing increasingly serious environmental problems, because of which carbon tax policies are being implemented, choosing the optimum cutting parameters during the machining process is crucial for automobile panel dies in order to achieve synergistic minimization of the environment impact, product quality, and processing efficiency. This paper presents a processing task-based evaluation method to optimize the cutting parameters, considering the trade-off among carbon emissions, surface roughness, and processing time. Three objective models and their relationships with the cutting parameters were obtained through input–output, response surface, and theoretical analyses, respectively. Examples of cylindrical turning were applied to achieve a central composite design(CCD), and relative validation experiments were applied to evaluate the proposed method. The experiments were conducted on the CAK50135 di lathe cutting of AISI 1045 steel, and NSGA-Ⅱ was used to obtain the Pareto fronts of the three objectives. Based on the TOPSIS method, the Pareto solution set was ranked to find the optimal solution to evaluate and select the optimal cutting parameters. An S/N ratio analysis and contour plots were applied to analyze the influence of each decision variable on the optimization objective. Finally, the changing rules of a single factor for each objective were analyzed. The results demonstrate that the proposed method is effective in finding the trade-off among the three objectives and obtaining reasonable application ranges of the cutting parameters from Pareto fronts.

Preparation and characterization of Mn/MgAlFe as transfer catalyst for SO_x abatement

A series of manganese-promoted MgAlFe mixed oxides, used as sulfur transfer catalysts, were prepared by acid-processed gelatin method and characterized by TGA-DTA, XRD, N2 adsorption-desorption and FT-IR techniques. It was found that the sulfur transfer catalysts with 0.5？3.0 wt% manganese showed its good dispersion in the precursor. The novel Mn/MgAlFe catalysts with 0.5？5.0 wt% manganese oxide showed a high oxidative adsorption rate and sulfur adsorption capacity, and 5.0 wt% Mn/MgAlFe sample was superior to the others for SO2 removal. Moreover, the presence of CO had no obvious effect on the adsorption activity of sulfur transfer catalysts for SO2 uptake.

Evaluation of H2 Influence on the Evolution Mechanism of NOx Storage and Reduction over Pt–Ba–Ce/c-Al2O3 Catalysts

In this investigation, Pt–Ba–Ce/c-Al2O3 catalysts were prepared by incipient wetness impregnation and experiments were performed to evaluate the influence of H2 on the evolution mechanism of nitrogen oxides (NOx) storage and reduction (NSR). The physical and chemical properties of the Pt–Ba–Ce/c- Al2O3 catalysts were studied using a combination of characterization techniques, which showed that PtOx, CeO2, and BaCO3, whose peaks were observed in X-ray diffraction (XRD) spectra, dispersed well on the c-Al2O3, as shown by transmission electron microscope (TEM), and that the difference between Ce3+ and Ce4+, as detected by X-ray photoelectron spectroscopy (XPS), facilitated the migration of active oxygen over the catalyst. In the process of a complete NSR experiment, the NOx storage capability was greatly enhanced in the temperature range of 250–350℃, and reached a maximum value of 315.3μmol·gcat^-1 at 350℃, which was ascribed to the increase in NO2 yield. In a lean and rich cycling experiment, the results showed that NOx storage efficiency and conversion were increased when the time of H2 exposure (i.e., 30, 45, and 60 s) was extended. The maximum NOx conversion of the catalyst reached 83.5% when the duration of the lean and rich phases was 240 and 60 s, respectively. The results revealed that increasing the content of H2 by an appropriate amount was favorable to the NSR mechanism due to increased decomposition of nitrate or nitrite, and the refreshing of trapping sites for the next cycle of NSR.

Durability of three-way and close-coupled catalysts for Euro IV regulation

The durability of three-way catalyst （TWC） and corresponding close-coupled catalyst （CCC） for Euro Ⅳ stage regulation was investigated through Vehicle Road Running Mode tests, whereas emissions of regulated pollutants of three car fleet were investigated at every 100,000 km miles. The results showed that HC, NOx, and CO emission values could meet Euro Ⅳ regulation limits at every point. The redox properties of TWC and CCC were measured by CO reduction during each isothermal. It was obvious that both aged TWC and aged CCC behaved a good redox property at 673 and 773 K. Based on XRD and BET measurement results, TWC and CCC washcoat were characterized with good thermal stability.

Influence of Al_2O_3/CeZrAl composition on the catalytic behavior of Pd/Rh catalyst

Al2O3 and Ce-Zr mixed oxides are important components of the automobile three-way catalyst.Various contents modifying A12O3(GAL) was physically introduced into Ce-Zr-Al mixed oxides(CZA) to form series of GAL/CZA composition.The Pd/Rh catalyst samples were prepared by different GAL/CZA support loading Pd/Rh,then aged at 950 oC for 6 h.The catalytic behavior of different Pd/Rh catalyst samples was studied.Surface area,oxygen storage capacity(OSC) and H2 adsorption capacity(TPR) of fresh and aged samples were...

Effect of catalyzed diesel particulate filter and its catalyst loading on emission characteristics of a non-road diesel engine

In this study, the effects of a diesel oxidation catalyst(DOC) coupled with a catalyzed diesel particulate filter(CDPF) with different catalyst loadings on the power, fuel consumption,gaseous and particulate emissions from a non-road diesel engine were investigated. Results showed that the after-treatment had a negligible effect on the power and fuel consumption.The reduction effect of the DOC on the CO and hydrocarbon(HC) increased with the engine load. Further reductions occurred coupling with the CDPF. Increasing the catalyst loading resulted in a more significant reduction in the HC emissions than CO emissions. The DOC could increase the NO_(2)proportion to 37.9%, and more NO_(2)was produced when coupled with the CDPF below 250℃;above 250℃, more NO_(2)was consumed. The after-treatment could reduce more than 99% of the particle number(PN) and 98% of the particle mass(PM).Further reductions in the PN and PM occurred with a higher CDPF catalyst loading. The DOC had a better reduction effect on the nucleation particles than the accumulation ones, but the trend reversed with the CDPF. The DOC shifted the particle size distribution(PSD) to larger particles with an accumulation particle proportion increasing from 13% to 20%, and the geometric mean diameter(GMD) increased from 18.2 to 26.0 nm. The trend reversed with the CDPF and the accumulation particle proportion declined to less than 10%. A lower catalyst loading on the CDPF led to a higher proportion of nucleation particles and a smaller GMD.

Low temperature catalytic conversion of carbon monoxide by the application of novel perovskite catalysts

Automobile exhaust contributes the largest sources of carbon monoxide(CO)into the environment.To control this CO pollution,the catalytic converters have been discovered.The catalytic converters have been invented for regulating the CO discharge.There are many types of catalysts have been investigated for CO emission control purposes.Inorganic perovskite-type oxides are fascinating nanomaterials for wide applications in catalysis,fuel cells,and electrochemical sensing.Perovskites prepared in the nanoscale have recently received more attention due to their catalytic nature when used as electrode modifiers.Perovskite catalysts show great potential for CO oxidation catalyst in a catalytic converter for their low cost,high thermal stability and tailoring flexibility.It is active for CO oxidation at a lower temperature.The catalytic activity of these oxides is higher than that of many transition metals compounds and even some precious metal oxides.They represents attractive physical and chemical characteristics such as electronic conductivity,electrically active structure,the oxide ions mobility through the crystal lattice,variations on the content of the oxygen,thermal and chemical stability,and supermagnetic,photocatalytic,thermoelectric and dielectric properties.The surface sites and lattice oxygen species present in perovskite catalysts play an important role in chemical transformations.The partial replacement of cations A and B by different elements,which changes the atomic distance,causes unit cell disturbances,stabilizes various oxidation states or added cationic or anionic vacancies inside the lattice.The novel things disturb the solid reactivity by varying the reaction mechanism on the catalyst surface.Thus,the better cations replacement may represent more activity.There are lots of papers available to CO oxidation over perovskite catalysts but no review paper available in the literature that is represented to CO oxidation.

Industrial Feasiblity of Direct Methane Conversion to Hydrocarbons over Fe-Based Fischer Tropsch Catalyst

Recently, as a direct consequence of the dwindling world oil reserves and the growing awareness of the environmental problems associated with the use of coal as energy source, there is growing interest in cheaper, abundant and cleaner burning methane. The Gas-to-Liquid technology offers perhaps the most attractive routes for the exploitation of the world huge and growing natural gas resources. Using this process the erstwhile stranded gas is converted to premium grade liquid fuels and chemicals that are easily transported. However, a widespread application of the GTL process is being hampered by economical and technical challenges. The high cost of synthesis gas, for instance, weighs heavily on the economics and competitiveness of the process limiting its wider application. This work presented a modified Gas-to-Liquid process that eliminates the costly synthesis gas production step. The proposed process utilized an alternative pathway for methane activation via the production of chloromethane derivatives which are then converted to hydrocarbons. It established that hydrocarbons mainly olefins can be economically produced from di- and tri-chloro- methanes over a typical iron-based Fischer Tropsch catalysts in a moving bed reactor at industrially relevant conditions. Some of the attractions of the proposed process include a) the elimination of the costly air separation plant requirement b) high process selectivity and c) significant reduction of carbon dioxide emissions thereby saving on feedstock loss and the costly CO2 removal and isolation processes.

Road Dynamic Distribution Analysis of Automobile Pollutants

With respect to the status of Qingdao road traffic and vehicle emissions conditions, this paper establishes vehicle pollutant emissions prediction model according to the theory. By the method of gathering the vehicle flow rate and speed data of Hong Kong Middle Road in Qingdao, it simulates motor vehicle emissions concentration at the point by combining with the corresponding wind speed, wind direction, vehicle emission factors and other parameters. The results show that as the wind speed increases motor vehicle emissions concentration will show a downward trend. However, CO and HC emissions decrease obviously with the increasing of the vehicle speed. The research provides corresponding control measures for the automobile pollution in Qingdao.

Effects of impregnation sequence on the NH_(3)-SCR activity and hydrothermal stability of a Ce-Nb/SnO_(2) catalyst

Hydrothermal stability is crucial for the practical application of deNO_(x)catalyst on diesel vehicles,for the selective catalytic reduction of NO_(x)with NH_(3)(NH_(3)-SCR).SnO_(2)-based materials possess superior hydrothermal stability,which is attractive for the development of NH_(3)-SCR catalyst.In this work,a series of Ce-Nb/SnO_(2)catalysts,with Ce and Nb loading on SnO_(2)support,were prepared by impregnation method.It was found that,the NH_(3)-SCR activities and hydrothermal stabilities of the Ce-Nb/SnO_(2)catalysts significantly varied with the impregnation sequences,and the Ce-Nb(f)/SnO_(2) catalyst that firstly impregnated Nb and then impregnated Ce exhibited the best performance.The characterization results revealed that CeNb(f)/SnO_(2)possessed appropriate acidity and redox capability.Furthermore,the strong synergistic effect between Nb and Sn species stabilized the structure and maintained the dispersion of acid sites.This study may provide a new understanding for the effect of impregnation sequence on activity and hydrothermal stability and a new environmental-friendly NH_(3)-SCR catalyst with potential applications for NO_(x)removal from diesel and hydrogenfueled engines.