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91.
Thermal stability of metal-supported catalysts for reduction of cold-start emissions in a wood-fired domestic boiler 总被引:5,自引:0,他引:5
The aim of the present work is to develop a catalyst based on a mixture of manganese oxides and platinum supported on a metallic monolith for abatement of emissions from wood combustion, particularly during the cold-start phase. The activity and the thermal stability of the catalysts have been studied in the laboratory, before performing tests in a wood-stove. The effect of the hydrothermal treatment at 900°C on the adherence of the washcoat onto a metallic substrate was studied using scanning electronic microscope. It revealed well-adhering washcoat onto the metallic support due to the growth of the alumina whiskers during the treatment. The influence of the amount of washcoat, as well as the influence of the concentration of manganese oxides in it (Mn: 5 to 20 mol%/Al2O3) on the activity of fresh and hydrothermally-treated catalysts were studied. The activity tests were carried out using a mixture of carbon monoxide, naphthalene and methane in the presence of air, steam and carbon dioxide to resemble the flue gases from wood combustion. On the fresh catalysts, containing the same total amount of manganese, a high concentration of manganese oxides in the washcoat favoured the oxidation of carbon monoxide and naphthalene, whereas a lower concentration of manganese oxides in the washcoat gave higher activity for the oxidation of methane. An increased total amount of manganese oxides in the catalysts, which had the same amount of washcoat, resulted in an increase in activity for the oxidation of the three combustibles. After thermal treatment at 900°C for 270 h in steam, most of the manganese oxide catalysts were activated for the oxidation of carbon monoxide and naphthalene while only being slightly deactivated for the oxidation of methane. The addition of manganese oxides in the washcoat, however, lowers the temperature of the γ- to -alumina phase transformation. Platinum (0.5 mol%) was added to the manganese oxide (10 mol%) catalyst to improve its activity. A platinum catalyst was also tested for comparison. The platinum and the mixed catalysts showed similar activity for the oxidation of carbon monoxide and naphthalene, while the mixed catalysts were more active for the oxidation of methane. A similarly mixed MnOx–Pt (10–0.5 mol%) catalyst supported on Al2O3 stabilised with 3% lanthanum, but at larger scale, was tested in a wood-stove. The possibility of pre-heating the catalyst during the start-up phase was studied. The tests revealed a strong decrease of the carbon monoxide and unburned hydrocarbons emissions during the start-up phase when the catalyst was pre-heated with hot air compared with no pre-heating or no catalyst. 相似文献
92.
F. Pajot Y. Atik C. Evesque S. Lefranc B. Leriche J.-P. Torre B. Bélier N. Marsot L. Dumoulin L. Bergé M. Piat E. Bréelle D. Prêle A. Benoit C. Hoffmann T. Durand P. Camus D. Santos Yong Jin M. Giard 《Journal of Low Temperature Physics》2008,151(1-2):513-517
New techniques in microelectronics allow to build large arrays of bolometers filling the focal plane of submillimeter and
millimeter telescopes. The expected sensitivity increase is the key for the next generation of space experiments in this wavelength
range. Superconducting bolometers offer currently the best prospects in terms of sensitivity and multiplexed readout. We present
here the developments led in France based on NbSi alloy thermometers. The manufacturing process of a 23 pixel array and the
test setup are described.
相似文献
93.
P. Berg 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1932,64(4):357-362
Ohne Zusammenfassung 相似文献
94.
95.
Khamsehpour B. Singer K.E. Van Den Berg J.A. Vickerman J.C. 《Electronics letters》1986,22(12):627-629
The effect of an undoped GaAs spacer layer at the heterojunction interface of MBE-grown n-AlxGa1?xAs/p+-GaAs diodes has been investigated by electroluminescence, dynamic secondary ion mass spectrometry and current/voltage measurements. A consistent picture emerges of the role of the spacer layer in accommodating beryllium migration. A simple procedure to optimise the spacer layer thickness is suggested. 相似文献
96.
97.
An efficient iterative method for solving quasi-static electromagnetic field problems is presented. A relaxation function is introduced in the quasi-static field equations. Then, the resulting equations can be solved by iteration. The method is similar to the one of solving a Laplace equation by computing the stationary state of a diffusion equation. Next, for a radially layered configuration the numerical results are compared with the results from an existing integral equation method. Subsequently, for a realistic three-dimensional model of a human knee numerical results are arrived at. 相似文献
98.
T Rankinen T Suomela-Markkanen S V?is?nen A Helminen I Penttil? A Berg C Bouchard R Rauramaa 《Canadian Metallurgical Quarterly》1997,46(12):1418-1423
The association between changes in physical activity, body weight, and diet and fasting plasma insulin was analyzed in a 2.5-year follow-up study of 146 men aged 50 to 60 years. Physical activity was assessed by a 7-day physical activity recall interview, diet by a 4-day food record, and plasma insulin radioimmunologically. Total physical activity decreased from (mean +/- SD) 45.1 +/- 10.1 to 39.0 +/- 6.1 metabolic equivalent (MET) hours (METh).d-1 and conditioning physical activity (> 5.0 METs) from 8.0 +/- 11.2 to 2.7 +/- 5.0 METh.d-1, whereas plasma insulin increased from 8.2 +/- 5.8 to 9.2 +/- 6.7 mU.L-1 and body weight from 80.5 +/- 12.0 to 81.6 +/- 11.6 kg during the follow-up period (P < or = .001 for all). The change in conditioning physical activity correlated inversely (r = -.34, P < .001) and change in body weight positively (r = .42,P < .001) with the change in plasma insulin level. With data adjusted for the baseline insulin level, cardiovascular health status, alcohol intake, change in body weight, smoking, age, and follow-up time, the odds ratio for an increase in fasting plasma insulin was 8.9 (95% CI, 2.1 to 37.1; P = .003) for men with the greatest decrease in conditioning physical activity (< -7 METh) compared with men who reported an increase in conditioning physical activity. The same logistic regression model showed an odds ratio of 9.9 (95% CI, 2.1 to 45.4; P = .003) for the increase in plasma insulin for subjects who gained more than 3.3 kg body weight compared with subjects who lost at least 0.6 kg. Men who consumed at least 12 g.d-1 alcohol at both examinations had an odds ratio of 12.8 (95% CI, 1.7 to 94.5; P = .012) compared with nondrinkers. These data suggest that in middle-aged men, a reduction in physical activity increases the risk for increased plasma insulin independently of alcohol intake and changes in body weight. 相似文献
99.
100.
v. Berg v. Braunschweig Müller-Using Nüsslein Rieck und Stahl 《Zeitschrift für Jagdwissenschaft》1972,18(2):114-120
Ohne Zusammenfassung 相似文献