Control of hydrocarbon cold-start emissions: A search for potential adsorbents

Iliyas, Abduljelil; Zahedi-Niaki, M. Hassan; Eić, Mladen; Kaliaguine, Serge

doi:10.1016/j.micromeso.2006.12.038

Cited by 62 publications

(36 citation statements)

References 16 publications

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“…The ''light-off'' temperature is considered to be the temperature at which 50% of the emissions are converted. A variety of methods have been proposed to improve cold start emission control, including electrical heating of the catalyst or gas entering the catalyst [1] and trapping hydrocarbons until the catalyst reaches light-off temperature [2][3][4][5][6], whereupon the hydrocarbons are released for oxidation.…”

Section: Introductionmentioning

confidence: 99%

“…We have recently studied some one-dimensional zeolites which could be employed as potential adsorbents for a HC trap during automotive cold-start emission period [2,7,8]. The proposed technique is based on single-file diffusion [4], by which lighter HC components are trapped by heavier ones, which may allow proper overlap of desorption temperature profile and catalyst working temperature, e.g., above catalyst light-off temperature.…”

Section: Introductionmentioning

confidence: 99%

“…The proposed technique is based on single-file diffusion [4], by which lighter HC components are trapped by heavier ones, which may allow proper overlap of desorption temperature profile and catalyst working temperature, e.g., above catalyst light-off temperature. ZSM-12 and SAPO-5 were selected as promising candidates from preliminary screening tests based on their high trapping capacities and desorption temperatures [2].…”

Section: Introductionmentioning

confidence: 99%

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One-Dimensional Molecular Sieves for Hydrocarbon Cold Start Emission Control

et al. 2009

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One-dimensional channel molecular sieves were synthesized and tested as hydrocarbon traps using toluene and ethylene as heavy and light HC probe molecules, respectively. Binary TPD traces of these two gases allow a systematic comparison of the adsorption/desorption behavior of molecular sieves. These results show a drastic difference between molecular sieves with 10 oxygen ring apertures (10R) and 12R. Ammonia TPD traces of the series of 12R molecular sieves allow to rationalize the different ethylene/toluene TPD traces.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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One-Dimensional Molecular Sieves for Hydrocarbon Cold Start Emission Control

et al. 2009

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“…Water is strongly adsorbed on high alumina zeolites, thus impeding the adsorption of reactive molecules in the active sites for the catalytic reactions. Moreover, metal-zeolites employed for the SCR of NOx are irreversibly damaged by the presence of water at high temperatures (Malka-Edery et al 2001;Yeon et al 2009;Iliyasm et al 2007).…”

Section: Introductionmentioning

confidence: 99%

FTIR studies of butane, toluene and nitric oxide adsorption on Ag exchanged NaMordenite

2011

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In this work, we studied the adsorption of butane, toluene and nitric oxide on NaMordenite exchanged with different amounts of silver. The reactions that occurred when the adsorbed hydrocarbons interacted with NO and the effect of water adsorption were also addressed. Different silver species were formed after ion exchange and they were detected by TPR analysis. Highly dispersed Ag 2 O particles were reduced at temperatures lower than 300°C whereas Ag + exchanged ions showed two TPR peaks, which can be ascribed to species exchanged at different mordenite sites. The TPD experiments after adsorption of NO at 25°C showed that the only desorbed species was NO 2 which was formed by the total reduction of Ag 2 O particles. When the adsorbed butane was exposed to NO (1000 ppm), isocyanate species were formed on Ag + ionic sites as well as Ag + -(NOx)-CO species. Toluene adsorption was stronger than butane since adsorbed toluene molecules were held even at 400°C. The characteristic bands of the aromatic ring C=C bond was observed as well as that of methyl groups interacting with Ag + and Na + ions. However, the appearance of carboxylic groups at temperatures above 300°C in inert flow indicated the partial oxidation of toluene due to Ag 2 O species present in the samples. After contacting adsorbed toluene with NO, different FTIR bands correspond to organic nitrocompounds, isocyanate, cyanide and isocyanide species adsorbed on Ag + ions, were detected. The presence of water inhibited the formation of NO 2 species and the hydrocarbon adsorption on Na + sites but did not affect the toluene-Ag + interaction.

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“…Investigation of one-dimensional microporous materials as hydrocarbon trapping media for controlling vehicle cold start emission has also been reported (Iliyas et al 2007;Sarshar et al 2009). As molecules diffuse in microporous materials, they exhibit the corresponding one-/threedimensional diffusion patterns.…”

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confidence: 99%

Characterization of the diffusion path in micro- and meso-porous materials from ZLC analysis

et al. 2010

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It has been demonstrated that the main diffusion paths of micro-and meso-porous UL-zeolites could be characterized from the Zero Length Column (ZLC) desorption curves with an appropriate theoretical analysis (Malekian et al., in Ind. Eng. Chem. Res. 46:5067, 2007). The present work extends this method to study the ZLC desorption data of n-heptane/cumene/mesitylene in three mesoporous SBA-15 samples, 1-methylnaphthalene in MCM-48, cumene in SBA-16 and toluene/cumene in a microporous one-dimensional boron SSZ-42. The investigation results revealed that the structure of SBA-15, MCM-48 and SBA-16 behaved approximately as three-dimensional (isotropic) diffusion system, while SSZ-42 behaved as one-dimensional (anisotropic) diffusion systems. The diffusion path did not change within the measured temperature range, and by using different sorbate molecules. This work confirmed that this effective and relatively inexpensive method can be used as an additional tool for the characterization of porous materials.

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Control of hydrocarbon cold-start emissions: A search for potential adsorbents

Cited by 62 publications

References 16 publications

One-Dimensional Molecular Sieves for Hydrocarbon Cold Start Emission Control

One-Dimensional Molecular Sieves for Hydrocarbon Cold Start Emission Control

FTIR studies of butane, toluene and nitric oxide adsorption on Ag exchanged NaMordenite

Characterization of the diffusion path in micro- and meso-porous materials from ZLC analysis

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