| 1. |
- Kanerva, Tomi, et al.
(författare)
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Microstructural characteristics of vehicle-aged heavy-duty diesel oxidation catalyst and natural gas three-way catalyst
- 2019
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Ingår i: Catalysts. - : MDPI AG. - 2073-4344. ; 9:2
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Tidskriftsartikel (refereegranskat)abstract
- Techniques to control vehicle engine emissions have been under increasing need for development during the last few years in the more and more strictly regulated society. In this study, vehicle-aged heavy-duty catalysts from diesel and natural gas engines were analyzed using a cross-sectional electron microscopy method with both a scanning electron microscope and a transmission electron microscope. Also, additional supporting characterization methods including X-ray diffractometry, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy and catalytic performance analyses were used to reveal the ageing effects. Structural and elemental investigations were performed on these samples, and the effect of real-life ageing of the catalyst was studied in comparison with fresh catalyst samples. In the real-life use of two different catalysts, the poison penetration varied greatly depending on the engine and fuel at hand: the diesel oxidation catalyst appeared to suffer more thorough changes than the natural gas catalyst, which was affected only in the inlet part of the catalyst. The most common poison, sulphur, in the diesel oxidation catalyst was connected to cerium-rich areas. On the other hand, the severities of the ageing effects were more pronounced in the natural gas catalyst, with heavy structural changes in the washcoat and high concentrations of poisons, mainly zinc, phosphorus and silicon, on the surface of the inlet part.
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| 2. |
- Nikkanen, Juha-Pekka, et al.
(författare)
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Synthesis of carbon nanotubes on FexOy doped Al2O3-ZrO2 nanopowder
- 2014
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Ingår i: Powder Technology. - : Elsevier BV. - 0032-5910. ; 266, s. 106-112
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Tidskriftsartikel (refereegranskat)abstract
- Carbon nanotubes (CNTs) were synthesized on liquid flame sprayed (LFS) powder substrate of iron oxide doped Al2O3-ZrO2. Iron oxide doped Al2O3-ZrO2 nanopowder was produced by injecting the liquid precursor of aluminium-isopropoxide, zirconium-n-propoxide, ferrocene and p-xylene into a high temperature (similar to 3000 K) flame. The precursor solution was atomized by high-velocity H-2 flow and injected into the flame where nanopartides were formed. The collected sample was used as a substrate material for the synthesis of CNTs. The CNTs were formed on the surfaces of the substrate powder by catalyzed decomposition of CH4. The particle morphology, size, phase composition and the nature of CNTs were determined by TEM, FE-SEM, XRD, XPS, Mossbauer and Raman spectroscopy. The collected powder consists of micron-sized agglomerates with nanosized primary particles. Tetragonal zirconia was detected while alumina was amorphous. In the carbonized sample multiwalled CNTs were obtained. (C) 2014 Elsevier B.V. All rights reserved.
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