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- DAWODY, JAZAER, 1959, et al.
(författare)
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E4-Mistra, a research program for the development of an energy efficient low emission exhaust aftertreatment system for heavy duty vehicles
- 2012
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Ingår i: World Renewable Energy Forum, WREF 2012, Including World Renewable Energy Congress XII and Colorado Renewable Energy Society (CRES) Annual Conference. - : American Solar Energy Society. - 9781622760923 ; , s. 4530-4536
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Konferensbidrag (refereegranskat)abstract
- This paper presents a unique system approach applied in a joint academic - industrial research program, E4 Mistra, to reach the goals of energy efficiency and low emissions exhaust aftertreatment system for heavy duty vehicles. The high energy efficiency is achieved by heat recuperation, on-board hydrogen production for use in both an auxiliary power unit and for NOx reduction and by finding new solutions for making the after-treatment system active at low exhaust temperatures. To reach low particulate emissions a mechanical filter using a sintered metal filter is developed. Low NOx emissions are achieved by an efficient NOx reduction catalyst. The system is based on four technological advances: Thermoelectric material s for heat recuperation, catalytic reduction of NOx over innovative catalyst substrates using hydrocarbons from the fuel and H2 from a high efficiency fuel reformer, and particulate filtration over a porous metal filter.
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| 2. |
- Arve, Kalle, et al.
(författare)
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Did Chemisorption Become an Obsolete Method With Advent of Tem? Comparison of Mean Particle Size and Distribution of Silver on Alumina
- 2011
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Ingår i: Catalysis Letters. - : Springer Science and Business Media LLC. - 1572-879X .- 1011-372X. ; 141:5, s. 665-669
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Tidskriftsartikel (refereegranskat)abstract
- Silver particle size and dispersion on a Ag/Al2O3 for HC-SCR were examined by means of chemisorption and TEM. Experimental results showed that determination of the accurate mean particle size (mps) is challenging and that the both applied methods have specific characteristics increasing the inaccuracy in the results which has to be taken into account in evaluation of catalytic activity. The results from TEM imaging were found to depend highly on the mode in which the surface was scanned (bright field versus dark field). Generally the point resolution was higher in dark field but the obtained mps did not increased along with the increasing silver loading. The main limitation with the O-2-chemisorption was related to the choice of the stoichiometric factor between the adsorbent and silver atoms. However, together these techniques support each other and help to give a more realistic picture of the mean silver particle size, distribution and indications of the oxidation states on the alumina support.
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| 4. |
- Creaser, Derek, 1966, et al.
(författare)
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Kinetic modeling of selective catalytic reduction of NOx with octane over Ag-Al2O3
- 2009
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Ingår i: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 90:1-2, s. 18-28
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Tidskriftsartikel (refereegranskat)abstract
- A kinetic model for the selective catalytic reduction of NOx with octane over a Ag-Al2O3 catalyst was developed. Analysis of experimental data indicated that feed concentrations of NO and hydrogen had significant effects on the NOx conversion, indicating that nitrates poisoned the catalytic sites and hydrogen’s role was to reduce nitrate species. As a result nitrate poisoning was a key component of the kinetic model. Also in the model, gas phase n-octane reacted with surface oxygen to form surface hydrocarbon intermediate species that could either reduce surface NO2 species to nitrogen or be fully oxidized. An additional site was included in the model on which various oxidation reactions occurred when the NOx reduction site was fully poisoned by nitrate species. The model also accounted for experimentally observed large temperature increases due to hydrogen oxidation, during hydrogen feed. The model was constructed from transient experimental data, both with and without hydrogen feed and from a range of reactant concentrations and temperatures.
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| 8. |
- Gunnarsson, Fredrik, 1983, et al.
(författare)
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Improved low-temperature activity of silver-alumina for lean NOx reduction–effects of Ag loading and low-level Pt doping
- 2014
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Ingår i: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 152-153:1, s. 218-225
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Tidskriftsartikel (refereegranskat)abstract
- This study focuses on the effect of silver loading and low-level platinum doping on the distribution of silver species, the hydrocarbon activation, and the low-temperature activity for lean NOx reduction over silver-alumina catalysts. Sol-gel prepared Ag/Al2O3 samples, withvarying silver loading and doped with trace amounts of platinum, were evaluated as HC-SCR catalysts using n-octane as reductant in a synthetic gas-bench reactor. In addition, the samples were characterized using X-ray photoelectron spectroscopy, ultraviolet visible spectroscopy, and the specific surface area was determined using nitrogen sorption. The study shows that as the samples are doped with trace-amounts of platinum, the activity for lean NOx reduction at low temperatures is enhanced. The catalyst composition that displays the highest activity for NOx reduction is a 2 wt% Ag/Al2O3 sample doped with 500 ppm platinum. This catalyst displays the highest low-temperature activity, most likely owing to an increased ability to adsorb and partially oxidize the hydrocarbon reductant, which is attributed to the Pt doping. Adsorption of a higher amount of hydrocarbons could result in that a lower amount of reducing agent is required for Pt doped Ag-alumina catalysts as compared to un-doped ones, which is beneficial with respect to fuel efficiency.
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| 9. |
- Gunnarsson, Fredrik, 1983, et al.
(författare)
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Influence of ageing, silver loading and type of reducing agent on the lean NOx reduction over Ag-Al2O3 catalysts
- 2013
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Ingår i: Topics in Catalysis. - : Springer Science and Business Media LLC. - 1572-9028 .- 1022-5528. ; 56:1-8, s. 416-420
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Tidskriftsartikel (refereegranskat)abstract
- The influence of ageing temperature, silverloading and type of reducing agent on the lean NOxreduction over silver–alumina catalysts was investigatedwith n-octane and bio-diesel (NExBTL) as reducing agent.The catalysts (2 and 6 wt% Ag–Al2O3) were prepared witha sol–gel method including freeze drying and the evaluationof NOx reduction and aging were performed using asynthetic gas-flow reactor. The results indicate a relatively high NOx reduction for both reducing agents. The hydrothermally treated 6 wt% Ag–Al2O3 sample displays amaximum NOx reduction of 78 % at 350 C for n-octane asreductant and the corresponding value for NExBTL is60 %. Furthermore, the catalysts show high durability andan increase in activity for NOx reduction after ageing attemperatures up to 650 C,with n-octane as reducingagent.
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