Catalyzed Diesel Particulate Filter Research Articles

Catalyzed diesel particulate filter modeling

Catalyzed diesel particulate filter modeling

Numerical simulation of continuously regenerating diesel particulate filter

In many countries, stricter exhaust emission standards are being set, and a diesel particulate filter (DPF) has been used to trap particulate matters (PM) including soot in diesel exhaust gas. It is reported that DPF filling with PM causes higher back-pressure and more fuel consumption, and continuously regenerating DPF is needed. Usually, to reduce the soot oxidation temperature, a catalyzed DPF is used. However, the phenomena inside DPF are not well understood, because it is difficult to conduct measurements inside the filter. In this study, we simulated soot oxidation and deposition by the lattice Boltzmann method to observe the transport process in continuously regenerating DPF. The inner structure of the filter was obtained by an X-ray CT technique. The reaction rate of soot oxidation by the Pt catalyst, as well as soot deposition probability in the numerical model, was evaluated in experiments. The soot trap and oxidation were investigated to discuss the conditions for the continuous regeneration. When the filter temperature (Tw) is 600K, the amount of deposited soot is quite similar to that without considering the soot oxidation, so that the soot is not oxidized at this temperature. When Tw is raised to be 800K, the amount of deposited soot is saturated. Thus, at Tw=800K or higher, the filter clogging can be avoided to achieve the continuous regeneration.

Emissions of PCDD/Fs, PCBs, and PAHs from legacy on-road heavy-duty diesel engines

Exhaust emissions of seventeen 2,3,7,8-substituted polychlorinated dibenzo-p-dioxin/furan (PCDD/F) congeners, tetra–octa PCDD/F homologues, 12 WHO 2005 polychlorinated biphenyl (PCB) congeners, mono–nona chlorinated biphenyl homologues, and 19 polycyclic aromatic hydrocarbons (PAHs) from three legacy diesel engines were investigated. The three engines tested were a 1985 model year GM 6.2J-series engine, a 1987 model year Detroit Diesel Corporation 6V92 engine, and a 1993 model year Cummins L10 engine. Results were compared to United States’ mobile source inventory for on-road diesel engines, as well as historic and modern diesel engine emission values. The test fuel contained chlorine at 9.8ppm which is 1.5 orders of magnitude above what is found in current diesel fuel and 3900ppm sulfur to simulate fuels that would have been available when these engines were produced. Results indicate PCDD/F emissions of 13.1, 7.1, and 13.6pg International Toxic Equivalency (I-TEQ)L−1 fuel consumed for the three engines respectively, where non-detects are equal to zero. This compares with a United States’ mobile source on-road diesel engine inventory value of 946pg I-TEQL−1 fuel consumed and 1.28pg I-TEQL−1 fuel consumed for modern engines equipped with a catalyzed diesel particle filter and urea selective catalytic reduction. PCB emissions are 2 orders of magnitude greater than modern diesel engines. PAH results are representative of engines from this era based on historical values and are 3–4 orders of magnitude greater than modern diesel engines.

Effect of fuel on the soot nanostructure and consequences on loading and regeneration of diesel particulate filters

An automotive diesel engine was tested in three representative modes of soot accumulation, active regeneration and spontaneous regeneration of its catalyzed diesel particulate filter (DPF), among the typical driving operation modes. During the engine tests, pressure and temperature along the DPF were measured, and soot samples were taken from the exhaust manifold upstream of the DPF for their thermal, structural and morphological characterization. The collected soot samples were subjected to: Transmission Electron Microscopy (TEM) for morphological analysis, thermal heating under oxidant atmosphere for studying the oxidation kinetics, Raman spectroscopy for describing their nanostructure and X-ray diffraction spectroscopy (XRD) for studying their internal lattice parameters. When the engine was operated in a typical accumulation mode, the pressure drop across the DPF increased up to 80 hPa with diesel fuel, while pressure drop stopped increasing after 4000 s of engine testing with biodiesel. In the regeneration mode, the DPF regenerated more slowly in the biodiesel case as a consequence of lower post-injected fuel energy and thus lower exhaust temperature. In the self-regenerating mode, the DPF was charged more slowly with biodiesel than with diesel fuel and its break even temperature was 40 °C lower with biodiesel fuel. These results provide further evidence that biodiesel soot is more reactive to oxidation. Although thermogravimetric results confirmed this tendency based on the differences on the pre-exponential factor, Raman spectra showed that biodiesel soot reached more ordered graphite-like structures and lower amorphous carbon concentration and XRD analysis showed that biodiesel soot displayed a higher degree of graphitization. The TEM analysis of the agglomerates showed that soot primary particles obtained with biodiesel fuel were significantly smaller and had higher specific active surface than those of diesel soot. From these results, an interpretation of the differences in soot oxidation between both soot samples was made based on the different length scales, from the carbon fringes to the particulate filter.

Analysis of Particle Mass and Size Emissions from a Catalyzed Diesel Particulate Filter during Regeneration by Means of Actual Injection Strategies in Light Duty Engines

The diesel particulate filters (DPF) are considered the most robust technologies for particle emission reduction both in terms of mass and number. On the other hand, the increase of the backpressure in the exhaust system due to the accumulation of the particles in the filter walls leads to an increase of the engine fuel consumption and engine power reduction. To limit the filter loading, and the backpressure, a periodical regeneration is needed. Because of the growing interest about particle emission both in terms of mass, number and size, it appears important to monitor the evolution of the particle mass and number concentrations and size distribution during the regeneration of the DPFs. For this matter, in the presented work the regeneration of a catalyzed filter was fully analyzed. Particular attention was dedicated to the dynamic evolution both of the thermodynamic parameters and particle emissions. The measurements were performed at the exhaust of a Euro 5 CR Diesel engine equipped with a Close Coupled DPF. The regeneration process was investigated in a point representative of an extraurban engine operating condition. The regeneration was managed by the electronic control unit (ECU). In particular, an injection calibration was implemented taking into account the engine and the filter features. The particle size distribution evolution during regeneration phase was measured in the size range 5-1000 nm using a differential mobility spectrometer. The particle mass concentration was monitored by means of a microsoot sensor. Particle mass and number concentrations strongly increase during the regeneration process. Moreover, a high concentration of the number of particles smaller than 30nm was observed in some critical phases of the regeneration process.

Emissions of PCDD/Fs, PCBs, and PAHs from a Modern Diesel Engine Equipped with Catalyzed Emission Control Systems

Exhaust emissions of 17 2,3,7,8-substituted chlorinated dibenzo-p-dioxin/furan (CDD/F) congeners, tetra-octa CDD/F homologues, 12 2005 WHO chlorinated biphenyls (CB) congeners, mono-nona CB homologues, and 19 polycyclic aromatic hydrocarbons (PAHs) from a model year 2008 Cummins ISB engine were investigated. Testing included configurations composed of different combinations of aftertreatment including a diesel oxidation catalyst (DOC), catalyzed diesel particulate filter (CDPF), copper zeolite urea selective catalytic reduction (SCR), iron zeolite SCR, and ammonia slip catalyst. Results were compared to a baseline engine out configuration. Testing included the use of fuel that contained the maximum expected chlorine (Cl) concentration of U.S. highway diesel fuel and a Cl level 1.5 orders of magnitude above. Results indicate there is no risk for an increase in polychlorinated dibenzo-p-dioxin/furan and polychlorinated biphenyl emissions from modern diesel engines with catalyzed aftertreatment when compared to engine out emissions for configurations tested in this program. These results, along with PAH results, compare well with similar results from modern diesel engines in the literature. The results further indicate that polychlorinated dibenzo-p-dioxin/furan emissions from modern diesel engines both with and without aftertreatment are below historical values reported in the literature as well as the current inventory value.

An Evaluation of Particle Size Distributions and Particle Number-Based Reductions from Various PM Emission Control Technologies

An Evaluation of Particle Size Distributions and Particle Number-Based Reductions from Various PM Emission Control Technologies

Reduction of Toxic Pollutants Emitted from Heavy-duty Diesel Vehicles by Deploying Diesel Particulate Filters

In this study, the emission characteristics of PCDD/Fs, PCBs and PBDEs from heavy-duty diesel vehicles, and the reduction of these above toxic pollutants by deploying three kinds of diesel particulate filters (DPFs), that is, mobile metal filter plus catalyzed diesel particulate filter (MMF + CDPF), diesel oxidation catalysts (DOC) + CDPF and partial diesel particulate filter (PDPF) were investigated. The tested vehicles were maintained at 60 km/h for 10 minutes on a standard chassis dynamometer. The results show that vehicles with greater mileage had higher PCDD/Fs, PCB and PBDE concentrations in the exhaust. After the tested vehicles were equipped with DPFs, some trials showed the formation of PCDD/Fs and PCBs occurring inside the DPF. This could be due to the de novo and precursor formation resulting from the combined effects of the accumulated particulate in the DPFs, favorable temperature and longer retention time for the exhaust. The PDPF exhibited the largest reduction in these toxic pollutants emitted from HDDVs, which reached 83.9%–95.3% on mass basis, and 54.2%–71.9% on toxicity basis. However, significant differences existed among the trials of these three DPFs, revealing that the influential factors for the reduction of these toxic pollutants could be more complex than those for reduction of particulate matter.

Instrumental and bio-monitoring of heavy metal and nanoparticle emissions from diesel engine exhaust in controlled environment

Abstract In the present article we characterized the emissions at the exhaust of a Common Rail (CR) diesel engine, representative of light-duty class, equipped with a catalyzed diesel particulate filter (CDPF) in controlled environment. The downstream exhausts were directly analyzed (for PM, CO, CO 2, O 2, HCs, NO x) by infrared and electrochemical sensors, and SEM-EDS microscope; heavy metals were chemically analyzed using mosses and lichens in bags, and glass-fibre filters all exposed at the engine exhausts. The highest particle emission value was in the 7-54 nm size range; the peak concentration rose until one order of magnitude for the highest load and speed. Particle composition was mainly carbonaceous, associated to noticeable amounts of Fe and silica fibres. Moreover, the content of Cu, Fe, Na, Ni and Zn in both moss and lichen, and of Al and Cr in moss, was significantly increased. Glass-fibre filters were significantly enriched in Al, B, Ba, Cu, Fe, Na, and Zn. The role of diesel engines as source of carbonaceous nanoparticles has been confirmed, while further investigations in controlled environment are needed to test the catalytic muffler as a possible source of silica fibres considered very hazardous for human health.

Potential Ozone Impacts of Excess NO2 Emissions from Diesel Particulate Filters for On- and Off-Road Diesel Engines

This study considers potential impacts of increased use of diesel oxidation catalysts (DOCs) and catalyzed diesel particulate filters (DPFs) on ozone formation in the Dallas/Fort Worth (DFW) area. There is concern that excess nitrogen dioxide (NO2) emissions from vehicles equipped with these devices could increase ambient ozone levels. The approach involved developing two scenarios for use of these devices, quantifying excess NO2 emissions in each scenario, and using a photochemical model to estimate the resulting ozone changes. In the “maximum penetration” scenario, DOC/DPF devices in a 2009 fleet of heavy-duty on-road trucks, school buses, and construction equipment were significantly increased by accelerating turnover of these vehicles and equipment to models that would require DOCs/DPFs. In the “realistic” scenario, current fractional usage of these devices was assessed for 2009. For both scenarios, excess NO2 emissions from DOCs/DPFs were estimated using U.S. Environmental Protection Agency’s MOBILE6 and NONROAD emissions inventory modeling tools. The emissions analyses were used to adjust the DFW photochemical modeling emissions inventories and the Comprehensive Air Quality Model with extensions air quality model was rerun for the DFW area to determine the impact of these two scenarios on ozone formation. The maximum penetration scenario, which showed an overall reduction in oxides of nitrogen (NOx) because of the accelerated turnover of equipment to cleaner models, resulted in a net decrease in daily maximum 8-hr ozone of 4–5 parts per billion (ppb) despite the increase in NO2 emissions. The realistic scenario resulted in a small increase in daily maximum 8-hr ozone of less than 1 ppb for the DFW area. It was concluded that the excess NO2 emissions from DOC/DPF devices result in very small ozone impacts, particularly for the realistic scenario, in the DFW area. There are noticeable decreases in ozone for the maximum penetration scenario because NOx reductions associated with DOC/DPFs (i.e., accelerated fleet turnover) exert more influence than excess NO2.

Development of High Performance Catalyzed DPF with New Soot Burning Mechanism

We developed ZrO2-based new catalysts that exhibit high carbon-burning performance and superior thermal stability for catalyzed diesel particulate filter (CDPF). Characterizations indicated that the developed ZrO2-based catalysts function by a new soot burning mechanism different from the conventional CeO2-based catalysts. Based on the results of evaluations using isotopic oxygen, we supposed that the ZrO2-based catalysts released active oxygen derived from the lattice of the oxides effectively as well as in the vicinity of the surface, while the conventional CeO2-based catalysts utilized active oxygen mainly from the vicinity of the surface. By amperometry of the inside of the catalysts applied during the carbon burning electric current was detected only for the ZrO2-based catalysts. Presumably, ZrO2-based catalysts promoted the carbon burning by a mechanism that oxygen ion in the lattice of the oxides is transferred to the active site with oxygen-ion conduction. An experiment to examine the carbon burning performance which simulated DPF regeneration showed that regeneration duration of the developed ZrO2-based catalysts was shortened by 33% compared with the shortest value for the conventional CeO2-based catalysts. The catalyst was also superior to the CeO2-based catalyst for the soot burning under the engine exhaust gas conditions. The new high-performance soot-burning catalyst developed in this study was introduced to the market in the end of 2008.

Sequence of monolithic converters DOC–CDPF–NSRC for lean exhaust gas detoxification: A simulation study

With increasingly strict automotive emission regulations the exhaust gas aftertreatment becomes more complex and expensive. Mathematical modelling and simulations play an important role in design of the aftertreatment systems consisting of multiple catalytic devices, reducing the time and cost demands of the system design. In this paper a combined exhaust gas aftertreatment system for diesel engines is studied. It consists of a diesel oxidation catalyst (DOC) for CO and hydrocarbons oxidation, a catalyzed diesel particulate filter (CDPF) for soot filtration, and an NO x storage and reduction catalyst (NSRC, also called lean NO x trap, LNT) for NO x abatement. Effective mathematical models of the individual converters are presented and used first to demonstrate the functionalities of the system, and then to conduct a parametric simulation study. The aim of this study is to map the influence of the individual components on the performance of the entire system in standard test driving cycle. The sizes of the DOC, CDPF, and NSRC converters are varied while the overall volume of the combined system is kept constant. The resulting maps of pressure drop, CO, HC, particulate matter, and NO x conversions show non-linear dependences on the sizes of individual converters. Co-operative and competitive effects occurring in the combined system are discussed. Suitable reactors sizes are found that enable high conversions of all controlled exhaust gas components.

Comparison of hot Soxhlet and accelerated solvent extractions with microwave and supercritical fluid extractions for the determination of polycyclic aromatic hydrocarbons and nitrated derivatives strongly adsorbed on soot collected inside a diesel particulate filter

Several methods of extraction were optimized to extract polycyclic aromatic hydrocarbons (PAHs), their nitrated derivatives and heavy n-alkanes from a highly adsorptive particulate matter resulting from the combustion of diesel fuel in a diesel engine. This particular carbonaceous particulate matter, collected at high temperatures in cordierite diesel particulate filters (DPF), which are optimized for removing diesel particles from diesel engine exhaust emissions, appeared extremely refractory to extractions using the classical extracting conditions for these pollutants. In particular, the method of accelerated solvent extraction (ASE) is described in detail here. Optimization was performed through experimental design to understand the impact of each factor studied and the factors’ possible interactions on the recovery yields. The conventional extraction technique, i.e., Soxhlet extraction, was also carried out, but the lack of quantitative extractions led us to use a more effective approach: hot Soxhlet. It appeared that the extraction of the heaviest PAHs and nitroPAHs by either the optimized ASE or hot Soxhlet processes was far from complete. To enhance recovery yields, we tested original solvent mixtures of aromatic and heteroaromatic solvents. Thereafter, these two extraction techniques were compared to microwave-assisted extraction (MAE) and supercritical fluid extraction (SFE). In every case, the only solvent mixture that permitted quantitative extraction of the heaviest PAHs from the diesel soot was composed of pyridine and diethylamine, which has a strong electron-donor character. Conversely, the extraction of the nitrated PAHs was significantly improved by the use of an electron-acceptor solvent or by introducing a small amount of acetic acid into the pyridine. It was demonstrated that, for many desirable features, no single extraction technique stound out as the best: ASE, MAE or SFE could all challenge hot Soxhlet for favourable extractions. Consequently, the four optimized extraction techniques were performed to extract the naturally polluted diesel soot collected inside the DPF. Comparisons with the NIST standard reference material SRM 1650b showed that the soot collected from the DPF contained 50% fewer n-alkanes, and also markedly lower levels of PAHs (44 less concentrated) than SRM 1650b, and that the ratio of nitroPAHs to PAHs was increased. These results were attributed to the high temperatures reached inside the particulate filter during sampling runs and to the contribution of the catalytic DPF to aromatic and aliphatic hydrocarbons abatement.

Reduction in the Emissions and Toxicity of Polycyclic Aromatic Hydrocarbons from a Heavy-duty Diesel Engine with the Latest Aftertreatment Devices

Polycyclic aromatic hydrocarbons (PAHs) bound in particles from automobile emissions may cause adverse human health. In this study, a 3L heavy-duty diesel engine with and without the latest aftertreatment devices were characterized for PAH emissions and toxicity using European Transient Cycle (ETC) and the European Stationary Cycle (ESC). The latest combination of aftertreatment devices including a diesel oxidation catalyst (DOC) and a catalyzed diesel particulate filter (c-DPF) were used to remove diesel exhaust particles (DEP). Particle size distribution and number concentrations were measured using a TSI Engine Exhaust Particle Sizer. Eight PAHs [benz(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, indeno(1,2,3cd)pyrene, dibenz(a,h)anthracene, and benzo(ghi)perylene] within the DEP were analyzed by thermal desorptiongas chromatography/mass spectrometry (TD-GC/MS). Elemental carbon (EC) and organic carbon (OC) were also analyzed with a thermal/optical carbon analyzer. The results indicated that 4-ring PAH emissions are larger than 5 or 6-ring PAH emissions, with and without the aftertreatment devices in place. Number concentrations of particles, PAHs and EC mass emissions in diesel exhaust were dramatically decreased by the aftertreatment devices: > 99%, > 97% and > 99%, respectively. To evaluate the toxicity of PAHs in the DEP, we calculated benzo(a)pyrene equivalent (BaPeq) emissions using a toxic equivalency factor (TEF). Total BaPeq emissions of eight PAHs were also substantially decreased by the aftertreatment devices (> 95%). However, the decrease rate of OC was lower than EC (> 72%). We demonstrated that number concentrations of DEP, PAH emissions, EC and BaPeq emissions were similarly and substantially decreased by the latest aftertreatment devices.

Diesel passenger car PM emissions: From Euro 1 to Euro 4 with particle filter

This paper examines the impact of the emission control and fuel technology development on the emissions of gaseous and, in particular, PM pollutants from diesel passenger cars. Three cars in five configurations in total were measured, and covered the range from Euro 1 to Euro 4 standards. The emission control ranged from no aftertreatment in the Euro 1 case, an oxidation catalyst in Euro 2, two oxidation catalysts and exhaust gas recirculation in Euro 3 and Euro 4, while a catalyzed diesel particle filter (DPF) fitted in the Euro 4 car led to a Euro 4 + DPF configuration. Both certification test and real-world driving cycles were employed. The results showed that CO and HC emissions were much lower than the emission standard over the hot-start real-world cycles. However, vehicle technologies from Euro 2 to Euro 4 exceeded the NOx and PM emission levels over at least one real-world cycle. The NOx emission level reached up to 3.6 times the certification level in case of the Euro 4 car. PM were up to 40% and 60% higher than certification level for the Euro 2 and Euro 3 cars, while the Euro 4 car emitted close or slightly below the certification level over the real-world driving cycles. PM mass reductions from Euro 1 to Euro 4 were associated with a relevant decrease in the total particle number, in particular over the certification test. This was not followed by a respective reduction in the solid particle number which remained rather constant between the four technologies at 0.86 × 10 14 km −1 (coefficient of variation 9%). As a result, the ratio of solid vs. total particle number ranged from ∼50% in Euro 1–100% in Euro 4. A significant reduction of more than three orders of magnitude in solid particle number is achieved with the introduction of the DPF. However, the potential for nucleation mode formation at high speed from the DPF car is an issue that needs to be considered in the over all assessment of its environmental benefit. Finally, comparison of the mobility and aerodynamic diameters of airborne particles led to fractal dimensions dropping from 2.60 (Euro 1) to 2.51 (Euro 4), denoting a more loose structure with improving technology.

Effects of hydrothermal aging on SiC-DPF with metal oxide ash and alkali metals

The silicon carbide used to make diesel particulate filters (SiC-DPF) has a maximum temperature of use, which is not the melting point of the filter material itself but rather the eutectic melting points of the ash materials and alkali metals deposited on the filter wall. Chemical reactions between the SiC filter and the other materials, i.e. ash materials and/or alkali metals, decrease the filtration efficiency and catalytic reactivity of engine out emission. The objective of this study is to understand the effect of hydrothermal aging on the SiC-DPF, and on the SiC-CDPF (catalyzed diesel particulate filter) deposited with ash materials and/or alkali metals. Hydrothermal aging simulated for the extreme condition of uncontrolled regeneration in DPF is carried out by using H 2O at high temperature. The surface change of the SiC filter was characterized in terms of the geometric microstructure and metal composites of the filter by using the SEM-EDS, BET and XRD. The accumulated ash materials and alkali metals in the SiC-DPF were an admixture, and the SiC-DPF after-treatment system always contained H 2O. According to the results, H 2O in the after-treatment system can be regarded as an influential factor of SiC-DPF durability even though the SiC itself has a very high melting point. The regeneration temperature has to be controlled under a critical value to ensure the durability of SiC-DPF in the after-treatment system, considering the fact that large quantities of ash materials, alkali metals and H 2O components are included in the exhaust gas.

Experimental Investigations and Dynamic Simulation of Diesel Particulate Filter Systems

AbstractThe complex dynamic behavior of a diesel particulate filter (DPF) system during the regeneration process can be well predicted by detailed numerical simulation. Simulation studies for diesel oxidation catalyst (DOC) and catalyzed DPF (CDPF) based on detailed kinetic experiments are presented for the relevant gaseous species and soot. Heterogeneous 1D models are used and solved with the PDEX‐Pack simulation package. The influence of soot morphology on the reaction kinetics in terms of reactive surface is experimentally investigated and included within the model. In a subsequent step, the impact of oxygen diffusion within the soot layer is assessed for the description of the regeneration process. Simulation results of the effects, including both morphology and oxygen diffusion, underline the complexity and necessity for detailed modeling of the DPF regeneration. Finally, the hydrocarbon injection assisted regeneration of a CDPF, with and without DOC, is discussed.

배기가스 온도 및 조성 변화에 따른 CDPF의 재생 특성에 관한 실험적 연구

The catalyzed diesel particulate filter (CDPF) is widely used for collecting soot from the exhaust gas of diesel engine. However, the CDPF need being regenerated after the soot accumulation. It is important to know characteristics of regeneration for CDPF with variation of exhaust gas temperature and composition. This study presents characteristics of regeneration according to variable exhaust gas composition. Furthermore, the experiment were performed variable gas temperature of CDPF inlet gas at each exhaust gas composition. Test-rig is used to control at each in let gas temperature and composition during regeneration of CDPF. Reaction intensity(Ic) is used to compare with each result. Experimental results indicated that increased concentration of NOx and O₂ lead to regenerate more greatly. Also, higher temperature of exhaust gas leads to make CDPF cleaner.

Pressure drop and heat transfer of catalyzed diesel particulate filters due to changes in soot loading and flow rate

When soot particles are loaded in a diesel particulate filter, it causes increase in back pressure of the exhaust system. To minimize this pressure drop due to DPF, the filter needs to be regenerated after a certain amount of soot has been accumulated. It is crucial to estimate the correct amount of soot that has been accumulated by measuring the differential pressure. It is also important to understand changes in pressure drop due to flow rate variations of the exhaust gas, since the pressure drop would be influenced by the exhaust flow rate as well as the amount of soot. Furthermore, the heat transfer characteristics of the catalyzed diesel particulate filter (CDPF) are another major issue, as the filter is occasionally exposed to high temperature gas. This study presents the characteristics of pressure drop according to the variation of soot loading and the mass flow rate in CDPF. In addition, heat transfer characteristics in the filter was investigated when a high temperature gas flows into the CDPF. Tests were performed in several CDPF samples having varying amounts of catalyst coating. Experimental results indicate that rig-based experiments are useful in understanding the characteristics of pressure drop in the CDPF. In the cake filtration region, a pressure drop has a proportional relationship according to soot loading and mass flow rate. It was found that an increased catalyst coating may lead to enhanced convective heat transfer.

Effects of additives Co, La, and Mn for Pt-based carbon oxidation catalysts

Catalyzed diesel particulate filter (CDPF) systems are viewed as the next generation after-treatment system for the diesel vehicle. The CDPF was coated with Pt catalyst to regenerate particulate matters (PM) continuously. This study was conducted to investigate the PM oxidation catalyst for the CDPF system. The promotional effects of additives Co, La, and Mn for Pt-based carbon oxidation catalysts are investigated by a model gas test. The order of temperature that CO formation happens sharply was Mn < Pt < Pt2 < La < Co, from low temperature to high temperature order. The additive Mn was able to decrease carbon oxidation temperature by 10 °C more than the Pt-only catalyst. The additive Mn has the advantage of generating CO, and it may have the possibility of NOx reduction. Coexistence of both C 3H 8 and carbon in CDPF (catalyzed DPF) may be helpful to activate the rate of carbon oxidation over the catalyst sites.