过渡金属卟啉／高价盐体系催化分子氧对芳烃侧链氧化的研究

研究了四-全氟苯基卟啉过渡金属(TPFPPM,M=Co、Mn、Fe)/高价金属盐体系催化分子氧对烷基芳烃侧链氧化反应.结果表明,TPFPPCo催化乙苯及其衍生物的侧链氧化时,加入底物1/800的K2Cr2O7对反应有很好的促进作用,乙苯最高转化率达55.2%,苯乙酮收率为51.0%.该催化体系对于取代烷基苯,如正丙苯、正丁苯和对-溴乙苯也具有很好的催化效果.     

Catalytic Oxidation of Cyclohexene with Molecular Oxygen on Hydrotalcite－like Compounds

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分子氧/醛/过渡金属盐体系选择性氧化二苯硫醚的研究(英文)

在温和的反应条件和三氧化二铁或三氧化二钴存在下 ,结合使用分子氧和正戊醛以及采用“一步法”的方式 ,可有效和选择性地发生二苯硫醚氧化成相应的亚砜或砜的反应。与传统的氧化剂相比 ,此方法更安全和简便。     

Gold Catalysts Supported on Crystalline Fe_2O_3 and CeO_2/Fe_2O_3 for Low-temperature CO Oxidation

High active and stable gold catalysts supported on crystalline Fe2O3 and CeO2/Fe2O3 were prepared via the deposition-precipitation method. The catalyst with a Au load of 1.0% calcined at 180 °C showed a CO conversion of 100% at -8.9 °C, while Au/CeO2/Fe2O3 converted CO completely at -16.1 °C. Even having been calcined at 500 °C, Au/Fe2O3 still exhibited significant catalytic activity, achieving full conversion of CO at 61.6 °C. The catalyst with a low Au load of 0.5% could convert CO completely at room temperature and kept the activity unchanged for at least 150 h. N2 adsorption-desorption measurements show that the crystalline supports possessed a high specific surface area of about 200 m2/g. Characterizations of X-ray diffraction and transmission electron microscopy indicate that gold species were highly dispersed as nano or sub-nano particles on the supports. Even after the catalyst was calcined at 500 °C, the Au particles remained in a nano-size of about 6―10 nm. X-ray photoelectron spectra reveal that the supported Au existed in metallic state Au0. The modification of Au/Fe2O3 by CeO2 proved to be beneficial to the inhibition of crystallization of Fe2O3 and the stabilization of gold particles in dispersed state, consequently promoting catalytic activity.     

Oxidation of Alcohols to Carbonyl Compounds, Benzylic Carbons to their Ketones, and Arenes to their Quinones with Molecular Oxygen in Subcritical Water

Summary. Molecular oxygen is used as an efficient oxidant for the conversion of alcohols into carbonyl compounds, benzylic carbons to their ketones, and arenes to their quinones in subcritical water in the absence of catalysts. The procedure utilizes water and does not require support materials and metal salts.     

含钴、锰杂原子分子筛上烷烃低温分子氧氧化

用水热法合成了MeAlPO-5,MeAPSO-35,MeAlPO-18(MeAPS-18(Me=Co,Mn)分子筛,并用XRD和TPD对其进行表征。考察了在氧气作氧化剂的情况下,辛烷在这些杂原子分子筛上的氧化反应行为。辛烷氧化反应产物中,除辛酮和辛醇外,还出现了辛烷裂解氧化产物和辛烷多氧代产物。不同结构的分子筛催化剂上,辛烷氧化反应产物的选择性差异不大。在含有较多酸中心的MeAPSO分子筛上,n(辛酮)/n(辛醇)比要高于相同结构的MeAlPO分子筛。催化剂转移实验显示,氧化反应在多相体系中进行。考察了反应时间和温度变化对辛烷氧化反应的转化率及产物选择性等的影响,根据实验结果对反应机理进行了讨论。     

Cobalt and Manganese Salts of <Emphasis Type="Italic">p</Emphasis>-Aminobenzoic Acid Supported on Silica Gel: A Versatile Catalyst for Oxidation by Molecular Oxygen

Summary.  A 1:1 molar ratio of the cobalt and manganese salts of p-amino benzoic acid supported on silica gel is an effective catalyst for the oxidation of various organic compounds in reasonable yields using molecular oxygen. The catalyst can be reused several times. Corresponding author. E-mail: mhashemi@sharif.edu Received April 30, 2002; accepted (revised) July 16, 2002     

Thermal oxide synthesis and characterization of Fe_3O_4 nanorods and Fe_2O_3 nanowires

Fe3O4 nanorods and Fe2O3 nanowires have been synthesized through a simple thermal oxide reaction of Fe with C2H2O4 solution at 200-600℃ for 1 h in the air. The morphology and structure of Fe3O4 nanorods and Fe2O3 nanowires were detected with powder X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The influence of temperature on the morphology development was experimentally investigated. The results show that the polycrystals Fe3O4 nanorods with cubic structure and the av...     

Oxidation of n-Butanol and 2-Pentanol with Molecular Oxygen in Supercritical CO2

Oxidation of n-butanol and 2-pentanol using molecular oxygen in supercritical (SC) CO2 with and without co-solvent is investigated. The results showed that the reaction selectivity is high when the reaction is carried out in SC CO2. It has been observed that co-solvent affects conversion and selectivity of the reaction considerably.     

Oxidation of Thiols to Disulfides with Molecular Oxygen in Subcritical Water

Summary. Molecular oxygen is used as an efficient oxidant for the oxidative coupling of thiols to disulfides in subcritical water in the absence of catalysts. The procedure utilizes water and does not require support materials and metal salts providing high yields (>90%).     

RuCl3/O2催化的叔胺与2-硅氧基呋喃衍生物的偶联反应研究

在RuCl3催化下, 分子氧作氧化剂, 叔胺和2-硅氧基呋喃衍生物发生氧化脱氢形成碳碳键的偶联反应. 水解后, 以良好的收率(88%)得到了相应化合物3, 用1H NMR, 13C NMR, IR, MS和HRMS对目标产物的结构进行了表征.     

分子氧无溶剂催化氧化法合成对叔丁基苯甲酸

在常压、无溶剂条件下,以氧气为氧化剂,醋酸钴为催化剂,研究了催化氧化对叔丁基甲苯(PTBT)合成对叔丁基苯甲酸(PTBA)的反应.考察了催化剂与PTBT质量比、促进剂类型、促进剂用量、氧气流速、反应温度、反应时间等因素对反应的影响,确定了优化的反应条件.在PTBT用量30mL、催化剂用量0.7g、乙醛促进剂用量0.3m...     

Oxidation of Styrene with Molecular Oxygen in Supercritical CO2

The oxidation of styrene with molecular oxygen catalyzed by PdCl2 CuCl2 has been investigated in supercritical CO2 with a batch reactor. The oxidative system of styrene contains four components at the beginning and seven components during the reaction. The critical temperature, critical pressure, and critical density at different conversions are determined by using a high-pressure view cell. The effect of phase behavior on the conversion and selectivity were studied. Experimental results showed that the critical parameters of the reaction mixture at fixed initial molar ratio changed with the conversion of reactant. The conversion of styrene reached maximum near the critical density of the reaction mixture. Product selectivity also varied with density of reaction mixture and could be tuned to some degree.     

Efficient and convenient oxidation of organic halides to carbonyl compounds by H2O2 in ethanol

Various primary and secondary organic bromides were oxidized by hydrogen peroxide in refluxing ethanol to give the corresponding aldehydes/and ketones in high yield up to 94%; organic chlorides were oxidized to the corresponding aldehydes/and ketones by the same oxidant in ethanol in the presence of 10 mol % of KBr as the catalyst.     

SO_2对Co_3O_4/Al_2O_3选择性催化氧化NO的影响

采用流动态原位IR ,TPD及XPS技术研究了NO及SO2 在Co3 O4 /Al2 O3 金属氧化物催化剂表面上的吸附及脱附行为 ,并与该催化剂上模拟烟道气中NO的选择性催化氧化活性相关联 ,考察了SO2 对该反应过程的影响及作用机理 .     

掺杂对Pd/Al2O3催化剂物相结构及表面氧性质的影响

采用XRD、DTA、TPD－MS及流动反应法等手段，研究了掺杂超细ZrO2对Pd／Al2O3催化剂物相结构、表面氧性能及催化活性的影响.结果表明，掺杂超细ZrO2，对催化剂Pd／Al2O3的载体物相变化（α－Al2O3的生成）有明显的抑制作用，很高了催化剂的贮氧能力及表面吸附氧的活性，从而提高了催化剂的耐热稳定性、氧化能力以及对贫氧气氛的适应能力．     

ZrO2改性对Pt/Al2O3催化剂上CO氧化性能的影响

用流动反应法、TPR和TPD－MS等技术研究了Pt／Al2O3催化剂掺杂ZrO2体系上CO的催化氧化反应、氧物种的还原及脱出－恢复行为．结果表明，掺杂ZrO2有利于催化剂上氧物种的脱出－恢复，从而促进CO氧化活性及表面活泼氧物种与氢的反应．并用催化剂集团结构适应理论对结果作出了解释．     

Efficient Selective Oxidation of Aromatic Alkanes by Double Cobalt Active Sites over Oxygen Vacancy-rich Mesoporous Co3O4

The development of efficient catalyst for selective oxidation of hydrocarbon to functional compounds remains a challenge. Herein, mesoporous Co₃O₄ (mCo₃O₄-350) showed excellent catalytic activity for selective oxidation of aromatic-alkanes, especially for oxidation of ethylbenzene with a conversion of 42 % and selectivity of 90 % for acetophenone at 120 °C. Notably, mCo₃O₄ presented a unique catalytic path of direct oxidation of aromatic-alkanes to aromatic ketones rather than the conventional stepwise oxidation to alcohols and then to ketones. Density functional theory calculations revealed that oxygen vacancies in mCo₃O₄ activate around Co atoms, causing electronic state change from Co³⁺_(Oh)→Co²⁺_(Oh). Co²⁺_(Oh) has great attraction to ethylbenzene, and weak interaction with O₂, which provide insufficient O₂ for gradual oxidation of phenylethanol to acetophenone. Combined with high energy barrier for forming phenylethanol, the direct oxidation path from ethylbenzene to acetophenone is kinetically favorable on mCo₃O₄, sharply contrasted to non-selective oxidation of ethylbenzene on commercial Co₃O₄.     

I2-mediated C3-formylation of indoles by tertiary amine and H2O

An I₂-promoted 3-formylation of free (N–H) and N-substituted indoles with tetramethylethylenediamine (TMEDA) and H₂O as the carbonyl source is achieved, providing 3-formylindole in moderate to excellent yields with good functional group tolerance. This procedure represents an exceedingly attractive alternative to the traditional formylation methods.     

CuO/Al_2O_3催化剂中毒与氧吸附

燃煤烟气属于贫燃燃烧 (燃烧时通入过量空气 )尾气 ,其中除含 NOx、SO2 外还含有 O2 等 ,与非贫燃系统尾气中 NOx 的催化还原脱除相比有着很大的不同 .目前这一领域的研究工作虽然取得一些进展 ,但仍有许多问题尚待解决 [1] .无论是 NOx 的催化还原还是催化分解 ,气相中存在的SO2 对非贵金属及其氧化物催化剂构成了严重威胁 ,原因是非贵金属氧化物很容易吸收 SO2 生成稳定的硫酸盐而使催化剂中毒失活 .为脱除烟气中的 NOx,有报道先将气相中的 NO催化氧化为NO2 ,然后将 NO2 和 SO2 同时液相吸收 .研究表明 ,作为 NO催化氧化的非贵…