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In this study, Al 2 O 3 , ZrO 2 , La 2 O 3 , and Y 2 O 3 were separately introduced into Pt/CeO 2 -MnO x catalyst to improve the thermal stability of catalysts and obtain a better soot and NO oxidation activity after thermal treatment. CeO 2 -MnO x -RO x (R = Al, La, Y, or Zr) mixed oxides were prepared by a co-precipitation method. The catalysts were characterized by XRD, BET, H 2 -TPR, CO chemisorption, XPS, TG analysis, soot–TPO, and NO–TPO. It is found that the introduction of R n + into CeO 2 -MnO x markedly increases the thermal stability of the catalysts for soot and NO oxidation, remaining a better catalytic oxidation activity. On the one hand, after high-temperature aging, for the modified catalyst Pt/CeMnRO x , the ignition temperature of soot oxidation ( T i ) and maximal soot oxidation rate temperature ( T m ) increase by 30–50 °C and 4–32 °C, respectively, whereas Al 3 + -modified catalyst shows the best thermal stability. On the other hand, due to a key role of NO 2 as a strong oxidizing agent in soot oxidation process, the NO oxidation activity is often considered as an important aspect. This work shows that R n + -modified catalysts display a better stability on NO oxidation activity after aging. Some factors leading to the thermal deactivation of catalysts are also discussed in this paper. [ABSTRACT FROM AUTHOR]

Transformation of As in the post-combustion zone has a significant effect on its emission characteristics. In this study, redistribution of As that occurs during the interaction between flue gas and ash has been elucidated using a double-layer fixed-bed reactor at 800–1000 °C. Herein, flue gas and ash samples with different As contents and inorganic components were produced by two varieties of coals. The As content in the ash with high Ca and Al contents increased after interacting with the flue gas with a high As content, indicating gaseous As adsorption. However, the As content in the ash decreased by up to 67% for other cases. The blank experiments showed that the As occurrences in ash were thermally stable, suggesting that the decrease was caused by the action of flue gas. Accordingly, the effect of flue gas components on the release of As from the ash was investigated. It was found that a significant amount of As release was primarily caused by the reaction of gaseous Na in the flue gas with the residual As in ash. A bi-directional interaction was observed between the high-temperature flue gas and ash, which led to the redistribution of As. Unlabelled Image • Interaction between high-temperature flue gas and ash caused As transformation. • Ash with high Ca and Al contents obviously adsorbed gaseous As in the flue gas. • Gaseous Na promoted the residual As release via reaction with aluminosilicate. [ABSTRACT FROM AUTHOR]

This paper addresses the possibility that dielectric-barrier-discharge (DBD) can provide in situ fuel processing to manipulate methane diffusion flame, and this technology may be extended to other higher-order hydrocarbon fuels. In this work, an in situ fuel processing system, by coupling a DBD generator to the fuel nozzle, was developed to examine the chemical effect of the DBD on enhanced ignition and inhibited extinction of a CH 4 /O 2 /Ar counterflow diffusion flame. Experimental results show that 25 kHz plasma reduces the ignition temperature by approximately 180 K, and extends the extinction limit by approximately 20% with a moderate stretch rate. DBD sustained in the fuel stream is expected to perform as a pool of radicals and active molecules to promote combustion, which was verified by the diagnosis of several key intermediate species. In situ planar laser-induced fluorescence (PLIF) technique mapped the profile of CH radical, and gas chromatograph measured some stable species, such as hydrogen and higher order hydrocarbons. Hydrogen is more reactive fuel; therefore, this paper gives further insight into hydrogen-enriched ignition by CHEMKIN-PRO, and it is found that the acceleration is approached through more efficient generation of H radical. • The dielectric-barrier-discharge (DBD) was used as in situ fuel processing technology and applied to a counterflow burner. • The plasma can decrease the ignition temperature by approximately 180 K and extend the extinction limit by approximately 20% under certain conditions. • The PLIF technique was employed to determine CH radical and verify in situ plasma effect, while a gas chromatograph was used to measure H 2 produced by plasma. • The kinetics of hydrogen enriched ignition were analyzed using CHEMKIN-PRO. [ABSTRACT FROM AUTHOR]