Partial Oxidation of Methane to Synthesis Gas over Hexaaluminates LaMAl11O19-δ catalysts

A series of M-substituted hexaaluminates LaMAl11O19-δ (M=Fe, Co, Ni, Mn, and Cu)were prepared and characterized by XRD, XPS, TPR and TGA techniques, respectively. They exhibited different reducibility and catalytic activity for partial oxidation of methane (POM) to synthesis gas. Among the LaMAl11O19-δ samples, LaNiAl11O19-δ showed the best catalytic activity for the topic reaction and selectivity for synthesis gas at 780 ℃ for 2 h. The conversion of CH4 was over 99.2%, and the product selectivity for both CO and H2 was above 90.3%.     

Effect of ionic interactions on the oxidation of Fe(II) with H2O2 in aqueous solutions

The oxidation of Fe(II) with H₂O₂ has been measured in NaCl and NaClO₄ solutions as a function of pH, temperature T (K) and ionic strength (M, mol-L^–1). The rate constants, k (M^–1-sec^–1), d[Fe(II)]/DT=-k[Fe(II)][₂O₂]at pH=6.5 have been fitted to equations of the formlog k = log k₀+ AI ^1/2+BI+CI ^1/2/T Where log k₀=15.53-3425/T in water; A=–2.3, –1.35; B=0.334, 0.180; and C=391, 235, respectively, for NaCl (=0.09) and NaClO₄ ( =0.08). Measurements made in NaCl solutions with added anions yield rates in the order B(OH) ₄ ^– >HCO ₃ ^– >ClO ₄ ^– >Cl^–>NO ₃ ^– >SO ₄ ^2– and are attributed to the relative strength of the interactions of Fe²⁺ or FeOH⁺ with these anions. The FeB(OH) ₄ ⁺ species is more reactive while the FeCO ₃ ⁰ , FeCl⁺, FeNO ₃ ⁺ and FeSO ₄ ⁰ species are less reactive than the FeOH⁺ ion pair. The general trend is similar to our earlier studies of the oxidation of Fe(II) with O₂ except for B(OH) ₄ ^– . The effect of pH on the logk was found to be a quadratic function of the concentration of H⁺ or OH^– from pH=4 to 8. These results have been attributed to the different rate constants for Fe²⁺ (k₀) and FeOH⁺ (k₁) which are related to the measured k by, k=k_0Fe + k_1FeOH, where _i is the molar fraction of species i. The rates increase due to the greater reactivity of FeOH⁺ compared to Fe²⁺. k₀ is independent of composition and ionic strength but k₁ is a function of ionic strength and composition due to the interactions of FeOH⁺ with various anions.     

K2CO3—KOH溶液中Tb（Ⅲ）氧化产物的组成

由于E_(Tb~(4 )/Tb~(3 ))~0= 3.1V,使得Tb(Ⅳ)很难以简单离子的形式存在于水(E_(1/2O_2 2H~ )= 1.22V)溶液中。要从水溶液中获得稳定的Tb(Ⅳ),必须降低其平衡电位,通常采用生成难溶盐、配合物或溶胶等方法。 Tb(Ⅳ)化合物最初多以焙烧法制备。Prost在2.5mol/L K_2CO_3-0.5mol/LKOH溶液中用电化学氧化法制得了Tb(Ⅳ)的聚合物,并求得在此条件下E_(Tb~(4 )/Tb~(3 ))=     

High performance liquid chromatographic separation of cholesterol oxidation products

Summary A fast, sensitive, high performance liquid chromatographic method for the simultaneous determination of cholesterol hydroperoxides and other major oxysterols, using two different detection systems (ultraviolet at 210 nm and light scattering), is here described. The hydroperoxy derivatives were obtained by cholesterol photoxidation, isolated by thin layer chromatography and joined with a standard mixture of 10 oxysterols (epoxy, hydroxy and keto derivatives). Aliquots were directly injected onto a 5-μm particle size, 25×0.46 cm i.d. Spherisorb S5 CN normal phase column, usingn-hexane/anhydrous ethanol (97:3, v/v) as mobile phase and a flow rate of 0.8 mL min⁻¹. This method allowed, in a single isocratic analysis, the separation and quantification of the primary and secondary cholesterol oxidation products in 30 minutes. The light scattering detector was particularly useful for the determination of nonderivatized 5,6-epoxides and cholestane-3β,5α,6β-triol. The sensitivity of both detectors was very similar for most of the oxysterols, except for the 5,6-epoxides and the 7-ketocholesterol. The method suitability for the determination of cholesterol oxidation products in food matrices was successfully tested on a saponified lipid extract from egg yolk powder.     

高锰酸根离子氧化烯烃反应机理的研究

高锰酸根离子氧化烯烃反应机理的研究王磊（淮北煤炭师范学院化学系，淮北２３５０００）关键词烯烃高锰酸根离子氧化机理碳碳双键是烯烃分子的官能团，通常情况下此官能团较活泼、易受亲电和亲核试剂的进攻。碱性的高锰酸根离子ＭｎＯ－４是烯烃羟化的经典试剂，同时导致...     

SYNTHESIS AND OXIDATION OF N-ALKYLACRIDANS

本文用金属钠和正戊醇还原N-烃基啶酮法合成了十一个N-烃基啶满,并用紫外光谱法研究了它们和DDQ、TCNE与CA的氧化反应。它们只能和DDQ形成电荷转移络合物,不能和TCNE或CA形成电荷转移络合物,其原因是DDQ有较强的络合能力和较弱的氧化能力,TCNE和CA则相反,有较弱的络合能力和较强的氧化能力。并用两种方法求得了N-烃基啶满的电离势(I_p)值,结果很接近。     

Surface functionalization of polymer latex particles. II. Catalytic oxidation of poly(methylstyrene) latexes in the presence of cetyltrimethylammonium bromide

Surface-functionalized cationic poly(methylstyrene) (PMS) latex particles containing aldehyde and carboxylic acid groups were successfully achieved via an emulsion polymerization of 3(4)-methylstyrene in the presence of cetyltrimethylammonium bromide, followed by an in-situ oxidation catalyzed by copper chloride and tert-butyl hydroperoxide (t-BuOOH). Factors such as the type of metal catalyst, oxidant, and their concentration strongly affected the rate of oxidation. Step addition of t-BuOOH resulted in both a higher degree of oxidation and a more uniform distribution of particle size of the functionalized PMS as compared to the batch addition method. The effect of organic solvent was found to be insignificant, and the oxidation could still proceed in its absence. The particle sizes increased significantly during the oxidation but could be controlled by using crosslinked PMS latexes. Finally, the versatility of this oxidation process was demonstrated by oxidation of the polymer with a solid loading as high as 28%. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 3585–3593, 1997     

Some features of RuCl3-catalyzed periodate oxidation of 3-N-substituted 5-allenyl-2,5-dichloro-4,4-dimethoxycyclopent-2-en-1-ones

3-N-Substituted 5-(1Z-carboxymethylene)-2-chloro-4,4-dimethoxycyclopent-2-en-1-ones have been prepared from the corresponding 3-N-substituted 5-allenyl-2,5-dichloro-4,4-dimethoxycyclopent-2-en-1-ones using selective oxidative cleavage of their allene bond by the RuCl₃−NaIO₄ system. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1646–1648, September, 1997.     

Chemiluminescence in O2 oxidation of organosodium compounds of polycyclic aromatic hydrocarbons and benzophenone

Chemiluminescence (CL) in oxidation of organosodium compounds by O₂ in THF was studied. Emitters of CL are excited complexes of polycyclic aromatic hydrocarbons, excimers¹(R·R)^*. The mechanism of their formation was proposed. The Na⁺, R^.−+O₂ CL system is a unique source for the selective generation of excimers of aromatic hydrocarbons. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 284–288, February, 1997.     

Oxidation of 2-dialkylaminomethyl-4,6-di-tert-butylphenols

Oxidative transformations of 2-dialkylaminomethyl-4,6-di-tert-butylphenols depend on the nature of the oxidant, the character of the substituents at the nitrogen atom, and the medium. A mechanism of the oxidation of these compounds is suggested. The molecular structure of the compound obtained as a result of oxidative trimerization of 2-dimethylaminomethyl-4,6-di-tert-butylphenol was established by X-ray structural analysis. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1328–1335, July, 1997.