Standing waves, clustering, and phase waves in 1D simulations of kinetic relaxation oscillations in NO+NH3 on Pt(1 0 0) coupled by diffusion

The Lombardo–Imbihl–Fink (LFI) ODE model of the NO+NH₃ reaction on a Pt(1 0 0) surface shows stable relaxation oscillations with very sharp transitions for temperatures T between 404 and 433 K. Here we study numerically the effect of linear diffusive coupling of these oscillators in one spatial dimension. Depending on the parameters and initial conditions we find a rich variety of spatio-temporal patterns which we group into four main regimes: bulk oscillations (BOs), standing waves (SW), phase clusters (PC), and phase waves (PW). Two key ingredients for SW and PC are identified, namely the relaxation type of the ODE oscillations and a nonlocal (and nonglobal) coupling due to relatively fast diffusion of the kinetically slaved variables NH₃ and H. In particular, the latter replaces the global coupling through the gas phase used to obtain SW and PC in models of related surface reactions. The PW exist only under the assumption of (relatively) slow diffusion of NH₃ and H.     

负载型双金属簇催化剂的多相一氧化碳加氢反应性能

负载型双金属簇催化剂的多相一氧化碳加氢反应性能索全伶，李晔（内蒙古工业大学化学工程系，呼和浩特０１００６２）殷元骐，金道森（中国科学院兰州化学物理研究所，兰州７３００００）关键词一氧化碳加氢，多相催化，双金属簇催化剂，钾效应。１．引言异核金属羰基簇作...     

Asymmetric Baeyer—Villiger oxidation: control of stereoelectronic demand

The recent development of asymmetric Baeyer—Villiger oxidation of prochiral and racemic ketones is briefly summarized, focusing on the regio- and stereocontrol of the oxidation attained by regulating the stereoelectronic demand in the step of rearrangement of the Criegee intermediate.Based on the report presented at the International Conference Modern Trends in Organoelement and Polymer Chemistry dedicated to the 50th anniversary of the A. N. Nesmeyanov Institute of Organoelement Compounds of the Russian Academy of Sciences (Moscow, May 30–June 4, 2004).Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1784–1794, September, 2004.     

铁羰基络合物制备的一氧化碳加氢催化剂的研究

本文采用Ｆｅ＿３（ＣＯ）＿（１２）制备担载型络合物催化剂。采用程序升温反应技术考察了这类催化剂（ＣＯ＋Ｈ＿２）的反应性能，井使用紫外漫反射光谱和穆斯堡尔谱对催化剂进行了表征。经２５０℃和１５０℃还原的Ｆｅ／γ－Ａｌ＿２Ｏ＿３催化剂不仅活性远远高于４５０℃还原的Ｆｅ／γ－Ａｌ＿２Ｏ＿３，而且前者在反应过程中有乙烯和乙烷生成，后者则只有甲烷生成。经２５０℃还原的Ｆｅ／分子筛催化剂的活性高于４５０℃还原的Ｆｅ／分子筛催化剂，而且前者在反应过程中有乙烯、乙烷和丙烯生成，后者则只有甲烷生成。紫外漫反射谱和穆斯堡尔谱结果表明：较温和条件下活化的催化剂上有金属于属键骨架的存在。     

Catalytic nitrobenzene oxidation of lignins

Alkaline nitrobenzene oxidation of hardwood and softwood lignins in the presence of redox and phase-transfer catalysts was studied. The selectivity of oxidation of lignins increased by 1.7 to 1.9 times. A possible mechanism of catalysis is discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 3004–3007, December, 1996.     

Electrochemical Oxidation of Compounds Containing 1,4-Dihydropyridine and Pyridinium Rings — Analogs of Gene Transfection Agents

A study was carried out on the electrochemical oxidation of 1,4-dihydropyridines, found as substituents in pyridinium salts, which are strong electron acceptors. The potentials for their oxidation in acetonitrile were determined. NMR spectroscopy was used to find the relative acidity of the N–H and C–H protons and the oxidation potentials were determined for the anionic products of the ionization of the N–H bond in dihydropyridine. The only product of the preparative electrolysis, in contrast to chemical oxidation, is the corresponding pyridine, namely, the oxidized dihydropyridine form.     

Fe(110)面上CO化学吸附状态的吸附历史依赖关系

Fe(110)面上直接在室温时吸附的CO同先在170 K吸附然后升温到室温的CO吸附有所不同. 前者有解离而后者无解离; 另外, 前者的饱和吸附量比后者低. 这可以用前者发生了解离来解释. 根据以上结果, 提出了以下的设想, Fe(110)面上的CO解离除了需要足够的热能而外, 还需要在表面的吸附位上有邻近的其它未被覆盖Fe原子的存在, 即需要一定的表面结构.