Emissions from Diesel Vehicles with and without Lean NOx and Oxidation Catalysts and Particulate Traps

Hammerle, R. H.; Ketcher, D. A.; Horrocks, R. W.; Lepperhoff, Gerhard; Hüthwohl, G.; Lüers, Bernhard

doi:10.4271/952391

Cited by 10 publications

(5 citation statements)

References 9 publications

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“…They span from enhancements of the combustion systems (i.e., exhaust gas recirculation, turbulence improvement, common rail injection, etc.) to the use of after-treatment devices that are able to remove soot from the exhaust stream. − Among these, filtering systems coupled with oxidation catalysts seems to be the most suitable …”

Section: Introductionmentioning

confidence: 99%

“…[7][8][9][10] Among these, filtering systems coupled with oxidation catalysts seems to be the most suitable. 11 Many catalysts that are potentially appropriate for the specific task were also proposed, because very different materials showed soot oxidation activity. They include (i) noble metals, which were thought to act essentially toward the SOF 12 but were found to trigger soot oxidation through the catalytic oxidation of NO to NO 2 , which, in turn, oxidizes soot; 13,14 (ii) metal oxides; [15][16][17][18] (iii) some mixtures of them; 19,20 (iv) perovskite-type oxides; 21 (v) spinel-type copper-chromite, 22 which seem slightly more effective than noble-metal catalysts; and (vi) more-complex catalysts that, based on the synergistic effect of several constituents such as transition and alkaline metals, are capable of being active for soot oxidation at temperatures slightly above 580 K. [23][24][25][26][27][28][29][30] These latter materials are specifically active toward the oxidation of the carbonaceous matrix of soot and, as a result, they are capable of catalyzing the oxidation of substantially all carbonaceous matter.…”

Section: Introductionmentioning

confidence: 99%

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Study of Properties of a Catalyst for Soot Post-Combustion by Thermogravimetry−Mass Spectroscopy (TG−MS) Analysis

Vaccaro

2005

Ind. Eng. Chem. Res.

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The intent of this work is to study the performance of a catalyst for soot combustion under reducing and oxidizing environments, to draw indications on the catalytic mechanism and on the implications of the sulfation process. Thermogravimetric (TG) analyses of the sulfated catalyst in reducing and oxidizing environments and on-line mass spectrometry (MS) analyses of the gaseous products of the TG analyses have been performed. The catalyst is able to reduce and oxidize, when treated in suitable environments. Both H 2 and carbon reduce the catalyst within comparable ranges of temperature, although the main products of the reductions are different. In addition, the temperature ranges within which the catalysts reoxidize after the reductions are practically coincident with the catalyst threshold temperature. The aforementioned findings have led us to address the catalyst reduction as the rate-limiting step of the soot oxidation process. Sulfation decreases the catalyst activity through two different mechanisms that involve different catalytic components. One, which is irreversible, is due to the chlorine substitution with sulfur, and the other, which is reversible, is likely related to the physical or chemical covering of some other catalytic compounds that do not contain chlorine initially.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Study of Properties of a Catalyst for Soot Post-Combustion by Thermogravimetry−Mass Spectroscopy (TG−MS) Analysis

Vaccaro

2005

Ind. Eng. Chem. Res.

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“…PM was reduced by a mere 17% when using Swedish Class 1 fuel without sulfur and 19% when the same fuel was doped to 0.05 wt% sulfur. No measurable NO X reduction was reported with either fuel (Hammerle, et al, 1995).…”

Section: Oxidation Catalystsmentioning

confidence: 81%

“…Some promise has been shown utilizing this injection method, but substituting urea for the diesel fuel injected into the exhaust. This urea system has shown NO X reduction of 69 to 84% depending on the testing cycle being utilized (Hammerle, et al, 1995). The urea being injected does however pose its own set of drawbacks which will be discussed in section…”

Section: Lean No X Catalystsmentioning

confidence: 99%

Performance evaluation of diesel particulate filters on heavy-duty vehicles

Rosepiler¹

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Diesel particulate filters, or DPFs, are exhaust aftertreatment devices used to reduce exhaust emissions from diesel powered vehicles. Typical designs have a wall flow filter element downstream of an oxidation catalyst, which oxidizes a portion of the NO present in the exhaust stream to form NO 2. The resulting NO 2 aides in the combustion of the soot collected in the wall flow filter element allowing for the complete breakdown of the soot within typical diesel exhaust temperatures, thus limiting the required maintenance on the filter elements to the removal of non-combustible ash. Three aspects of DPF performance were investigated: cold start performance, filter durability, and general efficiencies. The cold start performance evaluation determined that the filter elements trapped particulate matter prior to the DPF light-off temperature being reached, however there was no significant impact on white smoke emissions at any temperature range. The DPF light-off temperature was determined to be between 330°F and 450°F for the Engelhard DPX and between 375°F and 450°F for the Johnson-Matthey CRT. The filter durability study showed a slight degeneration of DPF performance as age and accumulated mileage increased. However, a definitive DPF life span could not be determined due to inconsistencies in the data from one testing round to the next. In the general efficiencies evaluation, CO emissions were reduced by greater than 84% for both DPF styles tested. HC emissions were reduced by 76% with the Engelhard DPX and by 81% with the Johnson-Matthey CRT. PM emissions were reduced by 94% and 82% by the Engelhard DPX and the Johnson-Matthey CRT respectively. No significant changes were recorded for total NO X (NO + NO2) or CO 2 emissions. Virginia University (WVU), the Washington Metropolitan Area Transit Authority (WMATA), the Westchester County Transit Authority (WCTA), the New York City Department of Sanitation (NYCDOS), and Ralph's Grocery fleet in Riverside, California. Multiple driving schedules were utilized through out this testing. Most driving schedules were cycles or routes developed to simulate the duty cycle of a specific fleet, although some driving schedules were standard cycles, such as the Central Business District (CBD) cycle. Details pertaining to the test vehicles, the driving schedules, and experimental results are given in Chapter 4 of this thesis, Test Vehicles, Driving Schedules, and Results. Conclusions drawn from this data about the performance of diesel particulate filters are shown in Chapter 5-Conclusions.

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“…This system, however, encourages tampering since removal of the injector would not influence engine performance and would enhance fuel economy. Some promise has been shown utilizing this injection method, but with the substitution of urea for the diesel fuel injected into the exhaust [39]. The use of urea poses its own set of drawbacks which will be discussed in the following section.…”

Section: Lean No X Catalystsmentioning

confidence: 99%

Investigation of techniques and effects of diesel particulate filter cleaning

Moles¹

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Investigation of Techniques and Effects of Diesel Particulate Filter Cleaning Nathaniel Moles As the emissions standards placed on diesel engine exhaust become more stringent, the use of exhaust aftertreatment devices such as diesel particulate filters has become a more attractive means to meet those standards. During the use of these filters some of the particulate captured, usually ash, begins to restrict the flow through the filter. This increases the backpressure in the exhaust system and requires routine cleaning maintenance. This study reviewed engine technology used to reduce particulate emissions and investigated the effects of off-line cleaning of diesel particulate filters using compressed air and water flowing in the reverse direction of the exhaust flow. The resulting effects of these cleaning procedures were examined by measuring the weight lost and the pressure drop across the filters at varying air flow rates. Both the differential pressure and weight loss indicated that most of the particulate was removed during the initial stages of compressed air cleaning. A maximum of 92% of the total filter weight was removed from a single filter with a maximum decrease of 65% of the differential pressure across the filter. Flowing water in the reverse direction was found to be one of the most effective options in cleaning these filters, but many filters have matting materials that are damaged when exposed to water. Compressed air blown in the reverse direction for a thirty minute time period is recommended with a subsequent twenty minute water cleaning, if water is not restricted by the manufacturer.

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Emissions from Diesel Vehicles with and without Lean NOx and Oxidation Catalysts and Particulate Traps

Cited by 10 publications

References 9 publications

Study of Properties of a Catalyst for Soot Post-Combustion by Thermogravimetry−Mass Spectroscopy (TG−MS) Analysis

Study of Properties of a Catalyst for Soot Post-Combustion by Thermogravimetry−Mass Spectroscopy (TG−MS) Analysis

Performance evaluation of diesel particulate filters on heavy-duty vehicles

Investigation of techniques and effects of diesel particulate filter cleaning

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