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排序方式: 共有74条查询结果,搜索用时 31 毫秒
31.
Jin-Gul Kim He-Min Lee Min-Ju Lee Ju-Heon Lee Jeong-Gon Kim Ji-Yong Jeon Soon-Ki Jeong Seung-Joon Yoo Seong-Soo Kim 《Journal of Industrial and Engineering Chemistry》2008,14(6):841-846
Effect of cobalt and rhodium promoter on NOx storage and reduction (NSR) kinetics was investigated over Pt/BaO/Al2O3. Kinetics of 2% cobalt loading over Pt/BaO/Al2O3 demonstrated highest NOx uptake during lean cycle, while reduction efficiency during rich cycle appeared most poor. In contrast to this, rhodium showed suppressing effect of NOx uptake during lean cycle and demonstrated an enhanced effect for the higher efficiency of NOx reduction during rich cycle. DRIFT study for NOx uptake and regeneration confirmed formation of surface BaNOx from the band at 1300 cm−1 and formation of bulk BaNOx from the band at 1330 cm−1. 相似文献
32.
A new low-temperature methanol synthesis method: Mechanistic and kinetics study of catalytic process
Mechanism and kinetics of catalytic process for a new low-temperature methanol synthesis on Cu/ZnO catalysts from syngas (CO/CO2/H2) using catalytically active alcohol promoters were investigated by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Two intermediate species, adsorbed formate species and alkyl formate species, were formed in this synthesis process. The adsorbed formate species easily reacted with ethanol or 2-propanol at 443 K and atmospheric pressure, and the reaction rate with 2-propanol was faster than that with ethanol. Alkyl formate was readily reduced to form methanol at 443 K and 1.0 MPa, and the hydrogenation rate of 2-propyl formate was found to be quicker than that of ethyl formate. As a promoter, 2-propanol exhibited a higher activity than ethanol in the reaction of the low-temperature methanol synthesis. 相似文献
33.
Michael Meredith 《Architectural Design》2013,83(2):96-103
Michael Meredith of MOS Architects examines his own practice's preoccupation with physics and the particle-oriented world, and the persistent problem of meaning and meaninglessness against the backdrop of the architecture of a previous era: a period that spanned the Deconstruction movement of the late 1980s and closed with Greg Lynn's seminal 1997 Architecture After Geometry edition of AD. 相似文献
34.
Mukundan Devadas Oliver Krcher Martin Elsener Alexander Wokaun Nicola Sger Marcus Pfeifer Yvonne Demel Lothar Mussmann 《Applied catalysis. B, Environmental》2006,67(3-4):187-196
The influence of NO2 on the selective catalytic reduction (SCR) of NO with ammonia was studied over Fe-ZSM5 coated on cordierite monolith. NO2 in the feed drastically enhanced the NOx removal efficiency (DeNOx) up to 600 °C, whereas the promoting effect was most pronounced at the low temperature end. The maximum activity was found for NO2/NOx = 50%, which is explained by the stoichiometry of the actual SCR reaction over Fe-ZSM5, requiring a NH3:NO:NO2 ratio of 2:1:1. In this context, it is a special feature of Fe-ZSM5 to keep this activity level almost up to NO2/NOx = 100%. The addition of NO2 to the feed gas was always accompanied by the production of N2O at lower and intermediate temperatures. The absence of N2O at the high temperature end is explained by the N2O decomposition and N2O-SCR reaction. Water and oxygen influence the SCR reaction indirectly. Oxygen enhances the oxidation of NO to NO2 and water suppresses the oxidation of NO to NO2, which is an essential preceding step of the actual SCR reaction for NO2/NOx < 50%. DRIFT spectra of the catalyst under different pre-treatment and operating conditions suggest a common intermediate, from which the main product N2 is formed with NO and the side-product N2O by reaction with gas phase NO2. 相似文献
35.
I. Nova L. Castoldi F. Prinetto V. Dal Santo L. Lietti E. Tronconi P. Forzatti G. Ghiotti R. Psaro S. Recchia 《Topics in Catalysis》2004,(1):181-186
The NO
x
storage process over Ba/Al2O3 and Pt–Ba/Al2O3 NSR catalysts has been analyzed in this study by performing experiments at 350 °C with NO2 and NO/O2 mixtures using different complementary techniques (Transient Response Method, in situ FT–IR and DRIFT spectroscopies). The collected data suggest that over the Pt–Ba/Al2O3 catalyst the NO
x
storage process from NO/O2 mixtures occurs forming at first nitrite species, which progressively evolve to nitrates. In addition, a parallel nitrate formation via disproportionation of NO2 (formed upon NO oxidation) cannot be excluded. 相似文献
36.
37.
The effects of asphaltenes on the particle size, and the surface charge of two montmorillonite clays having in water various particle sizes, flow behaviours, and cationic exchange capacities (CEC) are investigated. The aim of this work is to contribute to the comprehension of the mechanism by which the asphaltenes alter the mineral wettability in an oil reservoir. Thus, adsorption of asphaltenes onto clays was made from water-saturated toluene, and the resulting asphaltenes covered clays were dried to remove trace of solvent and then dispersed in water. Upon adsorption of asphaltenes onto various clays, the mineral surface charge is reduced and the aggregation of the clay particles is enhanced, as observed, respectively, by microelectrophoresis and scanning electronic microscopy (SEM). Further, the samples aqueous dispersion properties such as the natural pH and the electrical conductivity were found, in all instances, to be lower for the asphaltenes covered clays as compared to the bare minerals, indicating reduction by asphaltenes of the clay's CEC. It is shown that the asphaltenes adsorption from water-saturated toluene onto clay is higher for the solid mineral having in water and at natural pH, the lower surface charge, the highest particle size and presenting the highest yield point for flowing. 相似文献
38.
Francioso O Ferrari E Saladini M Montecchio D Gioacchini P Ciavatta C 《Journal of hazardous materials》2007,149(2):408-417
The purpose of the present study is to investigate, by means of thermogravimetric analysis (TG) and differential thermal analysis (DTA), diffuse reflectance infrared Fourier transform (DRIFT) and 2D nuclear magnetic resonance (NMR) spectroscopies, the structural features of the humic-like fraction (HLF) from olive pulp (OP), its effluents originated from the fermentation processes for hydrogen (EH2) and methane production (ECH4) and humic acid (HA) from soil amended with each of these materials. A considerable structural modification emerged between the HLF, in particular from the ECH4 effluent, which was characterised by a high content of polyphenolic and polypeptidic substances. The short-term amendment trial with OP and EH2 indicated that no chemical or structural changes in soil HA appeared. In contrast, the amendment with ECH4 substantially influenced the chemical and structural composition of soil HA. The structural interpretation performed by 2D NMR indicated the presence of aliphatic and aromatic protons while the sugar-like content and O-CH3 groups decreased with respect to the soil control HA. It emerges from this study that olive wastes contain stabilised humic-like material that may be recycled as an amendment in areas where olive trees are cultivated. 相似文献
39.
This work aims at obtaining comprehensive information on the corrosion behaviour of AA2024-T3 in oxalic acid solutions under different concentrations (0.007–0.2?M) and pH (2–6). Various tests to characterise the corrosion behaviour are performed, including weight loss and electrochemical tests. Coupon surfaces are examined using infinite-focus microscopy, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, Raman spectroscopy and diffuse reflectance infrared Fourier transform spectroscopy. Corrosion rates, anodic and cathodic reaction kinetics are detailed to provide a fundamental understanding of the electrochemical behaviour of AA2024-T3 as a function of pH and oxalate concentration. The synergistic effect of pH and oxalate concentration on corrosion of AA2024-T3 is evaluated for both AA2024-T3 matrix and main intermetallics (i.e. Al–Cu–Mg and Al–Cu–Fe–Mn) and the electrochemical behaviour of each constituent element in AA2024-T3 is systematically studied. 相似文献
40.
K. K. Pandey 《应用聚合物科学杂志》1999,71(12):1969-1975
Hard and softwood and wood constituent polymers (cellulose and lignin) were studied using Fourier transform infrared (FTIR) spectroscopy. The hollocellulose‐to‐lignin ratio was estimated for some of the timber species. The structural difference between Klason lignin isolated from softwood (Pinus roxberghii and cupressus lusitanica) and hard wood (Acacia auriculaeformis and Eucalyptus tereticornis) species was studied. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1969–1975, 1999 相似文献