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19. Blending effect of methanol on the formation of polycyclic aromatic hydrocarbons in the oxidation of toluene

Author

Suzuki, Shunsuke, primary, Kukkadapu, Goutham, additional, Ishii, Yudai, additional, Katsumic, Takuma, additional, Kinoshita, Koichi, additional, Takeda, Yoshinaka, additional, Sakaida, Satoshi, additional, Konno, Mitsuru, additional, Sakai, Yasuyuki, additional, Tanaka, Kotaro, additional, Oguma, Mitsuharu, additional, and Pitz, William J., additional

Published
2022
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23. Blending effect of methanol on the formation of polycyclic aromatic hydrocarbons in the oxidation of toluene.

Author

Suzuki, Shunsuke, Kukkadapu, Goutham, Ishii, Yudai, Katsumic, Takuma, Kinoshita, Koichi, Takeda, Yoshinaka, Sakaida, Satoshi, Konno, Mitsuru, Sakai, Yasuyuki, Tanaka, Kotaro, Oguma, Mitsuharu, and Pitz, William J.

Abstract

Methanol has been considered as a potential renewable liquid fuel and blending it with gasoline and diesel is an effective way to reduce greenhouse gas emissions from the transport sector. To understand the mixing effect of methanol on the formation of polycyclic aromatic hydrocarbons (PAHs) and oxygenated PAHs (OPAHs), the fuel-rich oxidation of toluene with and without methanol was studied using a flow reactor at atmospheric pressure, temperatures from 1050 to 1350 K, equivalence ratio of 9.0, and residence time of 1.2 s. The blending ratio of methanol was varied as 0% and 50% on a molar basis. Gas chromatograph mass spectrometer was employed to identify and quantify PAHs and OPAHs in gaseous products. A kinetic model on PAH growth up to five ring structures was used to investigate the blending effect on PAH and OPAH formation. Both experiment and modeling showed that PAH and OPAH production at lower temperatures was unexpectedly promoted in toluene/methanol oxidation compared with toluene oxidation, while their production in toluene oxidation was identical with or larger than that in toluene/methanol oxidation at elevated temperatures. In methanol oxidation, no PAHs were produced under the current experimental conditions. Kinetic analysis indicated that high methanol reactivity produced several radicals, such as OH, H, and HO 2 , which promoted toluene reactivity at lower temperatures, resulting in the enlargement of PAH and OPAH formation in toluene/methanol oxidation compared to neat toluene oxidation. When the temperature was increased, the effect of methanol blending was diminished based on the kinetic analysis. These results suggest that oxygenated fuels do not necessarily reduce PAH production, but promote it under some conditions. [ABSTRACT FROM AUTHOR]

Published
2023
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28. An Experimental Study on the Conversion of CaO to CaSO4During Diesel Particulate Filter Regeneration

Author

Tanaka, Kotaro, Sakai, Yasuyuki, Ishii, Yudai, Yokobayashi, Yusuke, Sakaida, Satoshi, and Konno, Mitsuru

Abstract

The deposition of ash on a diesel particulate filter (DPF) results in an increase in pressure drop across the aftertreatment system, which leads to reduced capacity for soot and an increase in frequency of regeneration to eliminate the soot. To estimate the amount of ash and design a reduction method for the accumulated ash on the DPF, a deeper understanding of the ash generation mechanism is required. Previous studies have found that ash sampled at exhaust manifolds comprises metal sulfate and some oxides, whereas ash accumulated on DPFs primarily comprises typical metal sulfates. Although metal oxides are converted to the metal sulfates, the conversion mechanism is not well understood. Herein, the formation mechanism of calcium sulfate (CaSO4), which is the main component of ash on DPFs, from calcium oxide (CaO) was investigated using a flow reactor. CaO was made to react with SO2, SO3, O2, and H2O, when passed through a diesel oxidation catalyst. Quantitative analysis of the ash components in the products was performed using ion chromatography. The concentrations of SO2, SO3, and H2O during the reaction were analyzed by Fourier-transform infrared spectroscopy. Based on the experimental results, it was found that CaSO4mainly formed from the reaction of CaO with SO2and SO3; whereas, H2O inhibited CaSO4formation owing to the change in physicochemical properties of CaO.

Published
2023
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36. Time-resolved Mid-infrared Measurements of Hydrogen Peroxide in the Low-temperature Oxidation of Iso-octane in a Rapid Compression Machine.

Author

Tanaka, Kotaro, Sugano, Shinya, Yokota, Naoya, Sakaida, Satoshi, Konno, Mitsuru, and Nakamura, Hisashi

Subjects
TIME-resolved measurements, HYDROGEN peroxide, OXIDATION, CHEMICAL models, LOW temperatures, TIME-resolved spectroscopy, MACHINERY
Abstract

Time-resolved quantitative measurements of hydrogen peroxide (H2O2) in the low-temperature oxidation of iso-octane in a rapid compression machine have been performed using mid-infrared absorption spectroscopy. H2O2 was detected in the 8-μm region, wherein H2O2 has the strongest absorption band. Owing to the weak interference of the absorption of iso-octane and H2O in the 8-μm region, H2O and iso-octane were detected in the 1.4- and 3.5-μm region, respectively. The cross-sections of H2O2 and H2O were calculated using parameters in the HITRAN database, and the iso-octane cross-section was measured using a rapid compression machine in the temperature and pressure ranges of 417–700 K and 100–700 kPa, respectively. The time-resolved quantitative H2O2 profiles in the low-temperature oxidation of iso-octane at 0.77 MPa, 642 and 660 K, and an equivalence ratio of 1.0 were successfully obtained. The H2O and iso-octane profiles were also obtained using this measurement method; the simultaneous measurements of the quantitative time profiles of multi-species in the low-temperature oxidation of fuels are also novel. Under experimental conditions, H2O2 was formed during the low-temperature oxidation of iso-octane, and its concentration gradually increased between the end of the low-temperature oxidation and start of the high-temperature oxidation. The calculated H2O2 profiles obtained using the latest chemical kinetic model of iso-octane showed the same tendency as the experimental profiles. [ABSTRACT FROM AUTHOR]

Published
2022
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