The oxidation of hydrogen and carbon monoxide mixtures over platinum

Dabill, David W.; Gentry, Stephen J.; Holland, H. B.; Jones, Alan R.

doi:10.1016/0021-9517(78)90016-7

Cited by 45 publications

(12 citation statements)

References 3 publications

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“…f i~~ = klcH2cOz/G mol Hz/(cm2Pt -s) (6) This assumption is consistent with earlier experimental observations (Dabill et a]., 1978;Stetter and Blurton, 1980) which suggest that at least in an oxidizing environment, the oxidation rates of CO and hydrogen over platinum are inhibited by CO to approximately the same extent.…”

Section: Development Of the Mathematical Model Reaction Kineticssupporting

confidence: 75%

Mathematical modeling of catalytic converter lightoff. Part II: Model verification by engine‐dynamometer experiments

Cavendish

1985

AIChE Journal

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A transient mathematical model has been developed which describes the behavior of packed-bed catalytic converters during warmup. Model predictions agree very well with the results of enginedynamometer experiments for three Ptalumina catalysts of widely different properties, thus demonstrating the validity of the model. General Motors Research LaboratoriesWarren, MI 48090 SCOPEUnited States federal regulations of automobile exhaust emissions are based on pollutant emissions measured while driving a vehicle over a prescribed driving schedule referred to as the Federal Test Procedure (FTP). This standardized emission test procedure requires that the vehicle under test be at room temperature for a minimum of 12 h before the test. For a short period of time after the cold start, emissions of hydrocarbons and CO from the engine are quite high due to the operation of the choke. To compound the problem, the catalyst is relatively cold at this time and thus is not fully operational. As a result of the combination of the high engine-out emissions and the low catalyst efficiencies, CO and hydrocarbon emissions during the first few minutes of the ETP (i.e., warmup period) account for a large fraction of the overall FTP tailpipe emissions (Pozniak, 1980;Kummer, 1980). Consequently, improving the warmup performance of catalytic converters is an effective means of reducing CO and hydrocarbon emissions on the FTP test.As is evident from the results of engine-dynamometer experiments presented here, catalyst properties have a strong influence on converter warmup performance. The converter models previously reported in the literature (e.g., Kuo et al., 1971;Harned, 1972;Bauerle and Nobe, 1973;Ferguson and Finlayson, 1974) were not designed to include details about the catalyst pellets and thus are not well-suited for studying the effects of the parameters associated with catalyst design. In our previous paper (Oh et al., 1980), a detailed mathematical model was developed which describes the behavior of a single catalyst pellet under transient conditions encountered during the warmup period of automobile exhaust catalytic converters. The singlepellet model treated catalyst pellets as composite porous media composed of concentric shells of differing physical and chemical properties. Such a multilayered configuration was found to be especially convenient for examining how the lightoff behavior of a catalyst pellet is influenced by its properties, such as the poison penetration depth, and the location and width of the noble metal band.In this paper, the second part of our converter modeling studies, we couple the single-pellet model with a mixing cell scheme to develop a mathematical model which is capable of predicting the warmup performance of the entire catalytic converter. Some of the results of model calculations presented provide useful insights into the dynamic behavior of packed-bed catalytic converters during warmup. In addition, the validity of the converter model is tested by comparing model predictions with the results of e...

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Section: Development Of the Mathematical Model Reaction Kineticssupporting

confidence: 75%

Mathematical modeling of catalytic converter lightoff. Part II: Model verification by engine‐dynamometer experiments

Cavendish

1985

AIChE Journal

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“…For the optimal DTDs at each mass flow rate with T in g = 525 K and 600 K, the coefficients (a f , a r and n 1 ) included in the catalyst distribution function, Eq. (18), are listed in Table 4. The CO conversion efficiency at steady-state of the three different catalyst distributions for the respective operating conditions is shown in Table 5.…”

Section: Tablementioning

confidence: 99%

“…Here, propylene (90%) and methane (10%) are considered to represent fast-and slow-oxidizing hydrocarbons, respectively. Hydrogen (H 2 ) oxidation is also incorporated because of the significant heat production associated with it, while its reaction kinetics are simple to treat as they are closely related to the oxidation kinetics of CO [18]. In this study, the oxidation reaction rates of CO, HC and H 2 are based on the Langmuir-Hinshelwood-type rate expressions [4,19] and the oxidation reaction schemes over Pt catalyst considered in this study are as follows.…”

Section: Reaction Kinetics Modelmentioning

confidence: 99%

Influences of exhaust gas temperature and flow rate on optimal catalyst activity profiles

Kim

Lee

2015

International Journal of Heat and Mass Transfer

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“…Methane (14%) and Propylene (86%) are used to model ''slow'' and ''fast'' oxidizing hydrocarbons, respectively. Hydrogen (H 2 ) oxidation is taken into account, due to the substantial heat production associated with it, whereas its reaction kinetics are simple to treat, because they are closely related to the kinetics of CO oxidation (Dabill et al, 1978). Here, the H 2 concentration is assumed to be 36% of the CO concentration.…”

Section: Chemical Reaction Modelmentioning

confidence: 99%

Influence of Spacing on the Thermal Efficiency of a Dual-Monolithic Catalytic Converter During Warmup

Kim

Jeong

Kim

2009

Environmental Engineering Science

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A one-dimensional monolithic catalyst model was used to evaluate the effect of space between two bricks on the thermal efficiency of a dual-monolithic catalytic converter with a Palladium-only (Pd-only) catalyst and a Palladium=Rhodium (Pd=Rh) catalyst butted together, and which are, in turn, mounted on a commercial vehicle equipped with a 2-L, four-cylinder spark ignition (SI) engine. Prior to the numerical investigation of the converter, tuning of the preexponential factor and activation energy of each reaction for each catalyst was performed to achieve acceptable agreement with experimental data under typical operating condition of automobile application. Two higher cell density 600 cpsi=4 mil substrates were used for faster light-off and improved warm-up performance of the catalytic converter, and the two monoliths have been connected without a space between them. As a result of the constriction of the monoliths, a slight temperature decrease occurred at the substrate interface due to thermal contact resistance. Therefore, to examine the heat transfer mechanism throughout the conforming rough surfaces, the thermal joint conductance between adjacent monoliths was determined using existing theory and correlation. The adequacy of the theory and correlation for thermal joint conductance was elucidated by analyzing heat transfer across the joint. Additionally, parametric investigations were performed to examine how the apparent contact pressure and mass flow rate of the exhaust gas affects the overall temperature drop across the joint. Over a wide range of operating conditions, temperature drop across the interface in the dual-catalyst converter with an air-gap is smaller than that without an air-gap. The relatively large temperature drop across the interface occurs especially during the early warmup period with a lower mass flow rate, that is, under conditions of cold-start and warmup at idle.

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The oxidation of hydrogen and carbon monoxide mixtures over platinum

Cited by 45 publications

References 3 publications

Mathematical modeling of catalytic converter lightoff. Part II: Model verification by engine‐dynamometer experiments

Mathematical modeling of catalytic converter lightoff. Part II: Model verification by engine‐dynamometer experiments

Influences of exhaust gas temperature and flow rate on optimal catalyst activity profiles

Influence of Spacing on the Thermal Efficiency of a Dual-Monolithic Catalytic Converter During Warmup

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