A Catalyzed Hydrocarbon Trap Using Metal-impregnated Zeolite for SULEV systems

Higashiyama, Kazutoshi; Nagayama, Toshiaki; Nagano, Masami; Nakagawa, Shinji; Tominaga, Shigeru; Murakami, Kazumi; Hamada, Ikuhisa

doi:10.4271/2003-01-0815

Cited by 10 publications

(3 citation statements)

References 5 publications

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“…On the other hand, low-temperature transient HC and CO performance is required in passenger vehicle applications, as reported by Tomazic et al Here, the mechanism by which zeolite improves transient HC and CO performance is relatively well-understood. Combustion on the catalyst starts with the diffusion of gases into the catalyst through micropores and macropores in the catalyst layer, followed by adsorption on the catalyst surface during cold-start mode and by desorption at elevated temperatures where HC and CO might be oxidized into CO 2 and H 2 O on the catalytically active sites, as reported by Higashiyama et al, Kim et al, Nakano et al, Seo et al, and Jiménez et al For this application, the adsorption quantity, desorption temperature, and catalyst light-off performance must be balanced. Nakano et al and Nagata et al reported that the HC light-off temperature must be lower than the HC desorption temperature to obtain high performance.…”

Section: Introductionmentioning

confidence: 99%

Modeling of Diesel Oxidation Catalyst

Tanaka

Hihara

Nagata

et al. 2005

Ind. Eng. Chem. Res.

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Optimization of hydrocarbon (HC) oxidation over a diesel oxidation catalyst (DOC) requires consideration of (i) HC gas diffusion into the catalyst layer, (ii) HC gas adsorption and desorption from catalyst sites, and (iii) kinetics of the oxidation reaction. We have already reported a brief modeling study that emphasized understanding HC storage and release from zeolitic sites within the DOC [Banno et al., SAE Tech. Pap. Ser. 2004-01-1430. In this study, more-detailed DOC modeling was attempted, using a precise gas diffusion model and experimentally determined reaction parameters. The random pore model was used for gas diffusion calculations, to simulate the bimodal nature of the catalyst structure, which has both macroporosity between catalyst particles and microporosity within the zeolite material. HC adsorption capacity, as a function of temperature and HC concentration, was measured by temperature-programmed desorption (TPD). The rate of HC desorption rate was evaluated by changing the TPD ramping rate. The rate of HC oxidation was measured using a model gas reactor. The conversion efficiency of HC, which was calculated by computer simulation with Star-CD software, reproduced the experimental measurements well, as a function of temperature, thus validating the model. The simulation methodology was used to predict two-dimensional (2D) HC conversion efficiency profiles across radial and axial positions of the monolithic catalyst during HC combustion, and it was also applied to estimate the depth profile of adsorbed HC in the catalyst layer.

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Section: Introductionmentioning

confidence: 99%

Modeling of Diesel Oxidation Catalyst

Tanaka

Hihara

Nagata

et al. 2005

Ind. Eng. Chem. Res.

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“…Other investigations have been conducted in real conditions, using a zeolite based HC trap located at the exhaust of a gasoline engine [23,24]. These studies have provided useful indication regarding the behaviour of selected materials towards the overall gas effluent, without discerning the effect of the adsorbent material on individual HCs.…”

Section: Journal Of Chemistrymentioning

confidence: 99%

MFI and FAU-Type Zeolites as Trapping Materials for Light Hydrocarbons Emission Control at Low Partial Pressure and High Temperature

Migliardini

Iucolano

Caputo

et al. 2015

Journal of Chemistry

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The adsorption of light hydrocarbons (C2–C5 olefins and paraffins, toluene) on HZSM-5, silicalite, and HY was studied for application in treatment of exhaust streams of the petrochemical industry and of vehicles under cold start conditions. At this aim the trapping capability was evaluated on hydrated zeolites by breakthrough curves at low hydrocarbon partial pressure (0-1 kPa), in the temperature range 298–523 K and at space velocity of 30000 h−1. The basic adsorption properties of materials were also verified for three selected hydrocarbons (ethylene, isobutene, and toluene) by equilibrium isotherms on dehydrated zeolites at 298 K. The role of physicochemical characteristics of adsorbent materials was discussed in relation with their trapping capability of different types of hydrocarbons.

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“…Since zeolites are already in use for catalyst purposes in the exhaust, especially as a hydrocarbon adsorbing material to store cold-start hydrocarbon emissions until the TWC reaches its light-off temperature (e.g. [10-15]), zeolite-based sensors might be suitable to withstand the harsh conditions in the exhaust.…”

Section: Introductionmentioning

confidence: 99%

Zeolite-based Impedimetric Gas Sensor Device in Low-cost Technology for Hydrocarbon Gas Detection

Reiß

Hagen

Moos

2008

Sensors

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Due to increasing environmental concerns the need for inexpensive selective gas sensors is increasing. This work deals with transferring a novel zeolite-based impedimetric hydrocarbon gas sensor principle, which has been originally manufactured in a costly combination of photolithography, thin-film processes, and thick-film processes to a low-cost technology comprising only thick-film processes and one electroplating step. The sensing effect is based on a thin chromium oxide layer between the interdigital electrodes and a Pt-loaded ZSM-5 zeolite film. When hydrocarbons are present in the sensor ambient, the electrical sensor impedance increases strongly and selectively. In the present work, the chromium oxide film is electroplated on Au screen-printed interdigital electrodes and then oxidized to Cr2O3. The electrode area is covered with the screen-printed zeolite. The sensor device is self-heated utilizing a planar platinum heater on the backside. The best sensor performance is obtained at a frequency of 3 Hz at around 350 °C. The good selectivity of the original sensor setup could be confirmed, but a strong cross-sensitivity to ammonia occurs, which might prohibit its original intention for use in automotive exhausts.

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A Catalyzed Hydrocarbon Trap Using Metal-impregnated Zeolite for SULEV systems

Cited by 10 publications

References 5 publications

Modeling of Diesel Oxidation Catalyst

Modeling of Diesel Oxidation Catalyst

MFI and FAU-Type Zeolites as Trapping Materials for Light Hydrocarbons Emission Control at Low Partial Pressure and High Temperature

Zeolite-based Impedimetric Gas Sensor Device in Low-cost Technology for Hydrocarbon Gas Detection

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