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961.
Catalytic ignition refers to phenomenon where sufficient energy is released from a catalytic reaction to maintain further reaction without additional extemai heating. This phenomenon is important in the development of catalytic combustion and catalytic partial oxidation processes, both of which have received extensive attention in recent years. In addition, catalytic ignition studies provide experimental data which can be used to test theoretical hydrocarbon oxidation models. For these reasons, catalytic ignition has been frequently studied. This review summarizes the experimental methods used to study catalytic ignition of light hydrocarbons and describes the experimental and theoretical results obtained related to catalytic ignition. The role of catalyst metal, fuel and fuel concentration, and catalyst state in catalytic ignition are examined, and some conclusions are drawn on the mechanism of catalytic ignition. 相似文献
962.
VOCs催化燃烧Pd-Y/不锈钢丝网催化剂的性能 总被引:2,自引:0,他引:2
采用经阳极氧化工艺处理后的不锈钢丝网作为催化剂载体,制备了Pd-Y/不锈钢丝网催化剂。考察了该催化剂对典型的挥发性有机物(VOCs)(甲苯、丙酮和乙酸乙酯)的催化燃烧性能,并用SEM、TPR技术对催化剂的形貌和氧化膜的结构组成进行了表征。结果表明:采用阳极氧化技术在不锈钢表面形成致密的多孔氧化膜,有利于活性组分的负载及均匀分散,明显提高了催化剂的燃烧活性和稳定性,延长了催化剂的使用寿命。Pd-Y/不锈钢丝网催化剂上3种VOCs的完全氧化温度分别为220、280和320 ℃。控制甲苯进料浓度为4~6 g·m 相似文献
963.
964.
Kaoru Honda Jaeheung Cho Prof. Dr. Takahiro Matsumoto Dr. Jungyun Roh Hideki Furutachi Dr. Takehiko Tosha Dr. Minoru Kubo Dr. Shuhei Fujinami Prof. Takashi Ogura Prof. Teizo Kitagawa Prof. Masatatsu Suzuki Prof. 《Angewandte Chemie (International ed. in English)》2009,48(18):3304-3307
In the nick(el) of time : Bis(μ‐oxo) dinickel(III) complexes 2 (see scheme), generated in the reaction of 1 with H2O2, are capable of hydroxylating the xylyl linker of the supporting ligand to give 3 . Kinetic studies reveal that hydroxylation proceeds by electrophilic aromatic substitution. The lower reactivity than the corresponding μ‐η2:η2‐peroxo dicopper(II) complexes can be attributed to unfavorable entropy effects.
965.
Fabrice Collin Dominique Bonnefont‐Rousselot Saï Yous Catherine Marchetti Daniel Jore Monique Gardès‐Albert 《Journal of mass spectrometry : JMS》2009,44(3):318-329
The hydrogen–deuterium exchange of protonated melatonin and its in vitro oxidation end‐products have been examined by liquid chromatography coupled with ion‐trap mass spectrometry. Specific H/D scrambling of protons in the C2 and C4 positions of the indole ring during gas‐phase fragmentation process was observed for both melatonin and its oxidation products. Collision‐induced dissociation spectra showed losses of variably deuterated NH3, H2O and CH3CONH2. In addition, a similar H/D scrambling behaviour was observed for the oxidation products, obtained from the opening of the indole ring by oxidative attack. Fragmentation pathways are proposed and H/D scrambling has been employed as a fingerprint, allowing identification of N1‐acetyl‐5‐methoxykynurenin (AMK), N1‐acetyl‐N2‐formyl‐5‐methoxykynurenin (AFMK), dehydro‐AFMK and hydroxymelatonin as the oxidation products of melatonin in vitro. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
966.
Dirk Lützenkirchen‐Hecht Hans‐Henning Strehblow 《Surface and interface analysis : SIA》2009,41(10):820-829
Silver (II) oxide layers (AgO) were prepared by anodic oxidation of pre‐oxidized, Ag2O‐covered silver electrodes in 1 M NaOH (pH 13.8). The oxidized electrodes were investigated using a combination of electrochemical techniques, ex situ X‐ray photoelectron spectroscopy (XPS) and in situ surface‐sensitive grazing incidence X‐ray absorption spectroscopy (EXAFS) under full potential control. The application of these different techniques leads to a detailed, consistent picture of the anodic silver (II) oxide layer formation. The experiments have shown that the chemical composition of the AgO layer varies significantly with oxidation potential, revealing a decreasing oxygen deficiency with increasing anodization potential and oxidation time. XPS as well as EXAFS experiments support the interpretation of the oxide as a mixed valence Ag + Ag3 + O2 with different contributions of Ag + and Ag3 + species, depending on potential and anodization time. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
967.
In the present work, we conducted an investigation on the electrochemical and ECL behavior of Ru(bpy) /TPrA system in the presence of pyridine and its analogues on platinum and gold electrode. Results showed that pyridine and its analogues enhanced Ru(bpy) /TPrA ECL signal and exhibited different enhancement effects on different electrodes. On platinum electrode, the maximum enhancement factor of about 5 was obtained. On gold electrode, a low‐oxidation‐potential (LOP) ECL signal occurred and increased. 相似文献
968.
Shuifa Qiu Yunyang Wei Prof. Dr. Guosheng Liu Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(12):2751-2754
Taking the air! A PdII‐catalyzed intramolecular hydroamination of allenes coupled to alcohol oxidation has been developed. This reaction is performed by using a nitrogen‐based ligand under aerobic conditions, under which the molecular oxygen is used as the terminal oxidant for the reoxidation of Pd0 species to complete the catalytic cycle.
969.
Yoichi M. A. Yamada Dr. Takayasu Arakawa Dr. Heiko Hocke Dr. Yasuhiro Uozumi Prof. Dr. 《化学:亚洲杂志》2009,4(7):1092-1098
Please recycle! An amphiphilic polystyrene‐poly(ethylene glycol) resin‐dispersion of nanoparticles of platinum (ARP‐Pt) is developed, with the nanoparticles exhibiting a narrow size distribution throughout the resin. ARP‐Pt offers a sustainable chemistry alternative as a useful and readily recyclable catalyst for the aerobic oxidation of a wide variety of alcohols.
970.
Gabriela Smeureanu Dr. Amit Aggarwal Clifford E. Soll Dr. Julius Arijeloye Erik Malave Charles Michael Drain Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(44):12133-12140
The catalytic oxidation of alkenes by most iron porphyrins using a variety of oxygen sources, but generally not dioxygen, yields the epoxide with minor quantities of other products. The turnover numbers for these catalysts are modest, ranging from a few hundred to a few thousand depending on the porphyrin structure, axial ligands, and other reaction conditions. Halogenation of substituents increases the activity of the metalloporphyrin catalyst and/or makes it more robust to oxidative degradation. Oxidation of cyclohexene by 5,10,15,20‐tetrakis‐(2,3,4,5,6‐pentafluorophenyl)porphyrinato iron(III), ([FeIII(tppf20)]) and H2O2 is typical of the latter: the epoxide is 99 % of the product and turnover numbers are about 350. 1 – 4 Herein, we report that dynamic organic nanoparticles (ONPs) of [FeIII(tppf20)] with a diameter of 10 nm, formed by host–guest solvent methods, catalytically oxidize cyclohexene with O2 to yield only 2‐cyclohexene‐1‐one and 2‐cyclohexene‐1‐ol with approximately 10‐fold greater turnover numbers compared to the non‐aggregated metalloporphyrin in acetonitrile/methanol. These ONPs facilitate a greener reaction because the reaction solvent is 89 % water and O2 is the oxidant in place of synthetic oxygen sources. This reactivity is unexpected because the metalloporphyrins are in close proximity and oxidative degradation of the catalyst should be enhanced, thus causing a significant decrease in catalytic turnovers. The allylic products suggest a different oxidative mechanism compared to that of the solvated metalloporphyrins. These results illustrate the unique properties of some ONPs relative to the component molecules or those attached to supports. 相似文献