长链烷烃选择性催化氧化合成脂肪酸

烷烃是最稳定的烃类,通常的氧化催化剂在不高的反应温度下很难对它产生催化作用。目前已大规模生产的烷烃液相氧化过程如丁烷氧化制醋酸、石蜡氧化合成脂肪酸等反应的选择性都不是很好,因而工艺流程复杂,或产物质量不高。从七十年代开始,为节省和充分利用资源,人们对于最稳定的烷烃的活化和催化氧化引起了较大兴趣。Onopchenko和Schulz等,以及Hanotier等都曾研究某些正构烷烃的选择催化氧化。但是至今长链烷烃的选择催化氧化合成脂肪酸仍是一个难题,本文报导我们最近在这方面研究中所取得的结果。     

磷酸铜锆催化剂上醇选择性氧化（英文）

The catalytic activity of copper zirconium phosphate(ZPCu) in the selective oxidation of alcohols to their corresponding ketones or aldehydes, using H2O2 as an oxidizing agent, was studied. The oxida‐tion reaction was performed without any organic solvent, phase‐transfer catalyst, or additive. Steric factors associated with the substrates influenced the reaction. The catalyst was characterized using X‐ray diffraction, inductively coupled plasma atomic emission spectroscopy, energy‐dispersive X‐ray spectroscopy, and scanning electron microscopy. It was shown that the interlayer distance increased from 0.74 to 0.80 nm and the crystallinity was reduced after Cu2+ intercalation into the layers. This catalyst can be recovered and reused three times without significant loss of activity and selectivity.     

磷酸锆镍上的醇选择性氧化（英文）

Nickel zirconium phosphate nanoparticles were found to function as efficient catalysts for the selective oxidation of a wide range of alcohols to their corresponding ketones and aldehydes using H2O2 as an oxidizing agent and without any organic solvents, phase transfer catalysts, or additives. The steric and electronic properties of various substrates had significant influence on the reaction conditions required to achieve acetylation. The results showed that this method can be applied for the chemoselective oxidation of benzyl alcohols in the presence of aliphatic alcohols. The catalyst used in the current study was characterized by ICP-OES, XRD, NH3-TPD, Py-FTIR, N2 adsorption-desorption, SEM and TEM. These analyses revealed that the interlayer distance in the catalyst increased from 0.75 to 0.98 nm when Ni2+ was intercalated between the layers, whereas the crystallinity of the material was reduced. The nanocatalyst could also be recovered and reused at least seven times without any discernible decrease in its catalytic activity. This new method for the oxidation of alcohols has several key advantages, including mild and environmentally friendly reaction conditions, short reaction time, excellent yields and a facile work-up.     

铁铜双金属催化剂选择性催化氧化氨为氮气(英文)

固定铜铁的总质量不变,采用共浸渍法制备铜铁双金属催化剂.为了更好地了解催化剂的性质,分别用N2吸附-脱附、H2-程序升温还原(H2-TPR)、NH3-程序升温脱附(NH3-TPD)、X射线衍射(XRD)和X射线光电子能谱(XPS)方法对制备的催化剂进行表征.研究发现在100000 h-1空速下,铜铁双金属催化剂呈现出好的活性和氮气选择性.在低温区,随着铜含量的增加,活性和氮气的选择性增加,然而在高温区氮气的选择性直接和铁的含量相关.其中催化剂Fe0.25Cu0.75/ZSM-5,在350°C氨的转化率达到最高,在300°C氮气的选择性上升到97%.Fe0.75Cu0.25/ZSM-5在500°C有很高的氮气选择性甚至可以达到98%.并且所有的催化剂均产生很少的N2O副产物.表征结果显示催化剂的酸量和铜物种的含量可以影响催化剂的活性,并且高的还原能力和铁含量有助于高温氮气选择性的提高.     

常压下Pt-Bi双金属催化剂上甘油选择性氧化(英文)

制备了一系列活性碳(AC)负载的Pt-Bi双金属催化剂,考察了催化剂中Bi含量对其催化甘油选择性氧化反应性能的影响.结果表明,适量Bi的添加可以改善催化剂中Pt的氧化还原性能,从而有利于催化剂活性的提高和二羟基丙酮(DIHA)产物的生成.当Bi的含量为5%时,该催化剂的活性最高,甘油转化率和DIHA选择性分别达到91.5%和49.0%.表征结果显示,Pt-Bi颗粒的平均粒径为3.8nm,且高度分散在催化剂表面,这是该催化剂具有较高活性的主要原因.     

快速功能化碳纳米管载 Pt 催化剂的醇氧化性能(英文)

采用HF刻蚀及交替微波加H2O2相结合的方法进行快速功能化碳纳米管(CNTs),应用红外光谱、拉曼光谱和透射电镜等方法详细考察了CNTs及其载Pt催化剂的物化性质,并采用循环伏安法、线性电流扫描法和计时电流法考察了所得催化剂的电化学性能.结果表明,CNTs经过HF刻蚀和交替微波H2O2双重处理后更适合用作催化剂载体,以10s-on/20s-off加热5次所得CNTs载Pt催化剂显示出最佳的催化性能.这可归因于处理后的CNTs表面含有丰富的微孔及含氧官能团,能有效增强Pt颗粒及CNTs间的相互作用.     

橄榄醇分子印迹聚合物的制备及评价(英文)

以橄榄醇为模板分子,α-甲基丙烯酸(MAA)为功能单体,乙二醇二甲基丙烯酸酯(EDMA)为交联剂,甲苯和十二醇为溶剂,通过本体聚合法制备了橄榄醇分子印迹聚合物。利用平衡结合实验、扫描电镜(SEM)及红外光谱(FTIR)对分子印迹聚合物(MIP)进行了表征,并用该聚合物进行了加标麦麸中橄榄醇的固相萃取(SPE)研究。平衡结合实验表明MIP对模板分子具有更好的识别性。Scatchard分析表明对橄榄醇分子的吸附存在2类不同结合位点,其中高亲和力结合位点和低亲和力结合位点的解离常数分别为0.021和1.002 mmol/L,相应的最大表观结合量分别为18.74和135.9 μmol/g。在优化的固相萃取条件下,MIP固相萃取柱对加标麦麸中橄榄醇的回收率达到97.8%~98.8%,相对标准偏差为2.8%~4.2%(n=5),线性范围为0.1~100 mg/L,检出限(S/N=3)为0.062 mg/L。与非印迹聚合物(NIP)柱及市售聚苯乙烯/二乙烯基苯(PLS)柱相比,MIP柱的选择性更强,回收率更高,纯化效果更好。     

苄醇的选择性间接电氧化

以Ｃｅ￣（４＋）／Ｃｅ￣（３＋）为氧化还原体系，以硫酸为支持电解质，采用槽内法研究了苄醇的选择性间接电氧化。得出最佳电解条件：电流密度，０．１Ａ／２０ｃｍ￣２；亚铈与反应物当量比，１：６；硫酸浓度，３ｍｏｌ／Ｌ；通过电量，２Ｆ／ｍｏｌ（Ｆ为理论电量）。在最佳电解条件下，反应产物为苯甲醛，产率高达９６％，不发生深度氧化。阳极液循环１０次以上，对反应产率无影响。反应中Ｃｅ￣（４＋）只起电子传递作用，反应仅消耗电能，因此此法十分经济，且无污染。     

可见光诱导的醇的选择性氧化

在蓝光照射的无金属、无添加剂的绿色温和条件下,以2-氯蒽醌为光催化剂,空气/氧气为氧化剂,高选择性地将芳族与杂芳族取代的伯醇和仲醇转化为相应的羰基化合物.实验结果表明,该催化剂具有较宽的底物适用范围,为苄基位含氧化合物的合成提供了一条经济、环保和可持续的新路径,具有潜在的应用前景.     

金属卟啉/MgAl水滑石催化醇选择性氧化制备羰基化合物

将MgAl水滑石引入到金属四苯基卟啉(MTPPs,M=Co,Fe,Mn,Ni)催化氧化体系中,实现了醇的选择性氧化。 结果表明,在分子氧/异丁醛体系中,CoTPP在苯甲醇氧化制苯甲醛反应中表现出优异的催化活性,MgAl水滑石添加剂可有效地提高醛的选择性。 在苯甲醇1 mmol、乙腈2 mL、CoTPP 5 mg、MgAl水滑石18 mg、异丁醛5 mmol、反应温度60 ℃、氧气气氛下反应2 h,苯甲醇的转化率和苯甲醛的选择性分别达到94%和92%。 另外,此催化体系在其它醇类化合物的氧化反应中也具有较好催化活性。     

Oxidant-free oxidation: ruthenium catalysed dehydrogenation of alcohols

The oxidation of alcohols has been achieved using Grubbs’ catalyst or a ruthenium p-cymene complex without the presence of an added oxidant.     

Enhanced electrochemical activity for ethanol oxidation on the carbon-supported Pt3Te nanocatalysts by addition of Ru

Ternary Pt–Te–Ru catalysts with different atomic ratios were synthesized by reducing the precursor with formic acid. The physical and electrochemical characterization of the Pt₃TeRu_0.25/C catalyst was performed by transmission electron microscopy (TEM), X-ray diffraction, energy-dispersive X-ray spectroscopy equipped with TEM (TEM-EDX), X-ray photoelectron spectrometer, ethanol oxidation, and CO stripping. In TEM images, the Pt₃TeRu_0.25/C nanoparticles with an average particle size of around 2.9 nm were well dispersed on the carbon support. The Pt₃TeRu_0.25/C catalyst was superior to the Pt₃Te/C catalyst in respect of catalytic activity, durability, and CO tolerance. The positive effect of the Ru presence in the Pt₃TeRu_0.25/C catalyst was ascribed to the interactions of Ru or Ru oxides.     

Efficient selective oxidation of alcohols to aldehydes catalyzed by a morpholinone nitroxide

Efficient chemoselective oxidation of primary alcohols to the corresponding aldehydes is described. The transformation is promoted by a catalytic morpholinone nitroxide radical catalyst which can be easily synthesized. A broad range of substrates including aromatic and aliphatic primary alcohols are converted with excellent yields under mild conditions. The control experiments reveal that the morpholinone nitroxide can be used as a selective oxidant for primary alcohols in the presence of secondary alcohols.     

Supported ruthenium catalyst as an effective catalyst for selective oxidation of toluene

The investigation comprised an evaluation of the use of the catalyst 1%Ru/TiO₂ in the liquid-phase conversion of toluene to benzyl alcohol and benzaldehyde. Transmission electron microscopy (TEM) and N₂ adsorption-desorption isotherms were deployed to delineate the properties of the supported catalysts. The findings indicated a good catalytic performance by 1%Ru/TiO₂ under green reaction conditions. This performance was deemed a consequence of the spread and loading of Ru on the TiO₂. The reaction conditions such as temperature, reaction time, type of support, catalyst preparation method, and activating quantity) were optimized to achieve superior reaction parameters. Catalyst produced via sol-immobilization has higher activity than the one prepared with the wet-impregnation method, which lead to a transformation rate of up to 9.5%, with the selectivity for benzyl alcohol at 92%.     

Ultrasound-assisted synthesis of CoFe2O4/Ce-UiO-66 nanocomposite for photocatalytic aerobic oxidation of aliphatic alcohols

During the past years, light-driven selective oxidation of various alcohols has attracted increasing attention as a green and eco-friendly manner to convert visible light energy into valuable compounds. In this work, magnetic CoFe₂O₄/Ce-UiO-66 embedded structure composites are elaborately designed for the photocatalytic oxidation of aliphatic alcohols under visible-light irradiation and aerobic condition at room temperature. The CoFe₂O₄/Ce-UiO-66 structure was prepared using a simple and fast ultrasound-assisted technique in 60 min at room temperature. As compared with the unmodified CoFe₂O₄, the embedded composite exhibited better visible-light sensitization performance. The catalyst showed high chemical stability in the reaction conditions and can be recovered quickly and reused for at least five reaction runs in the aerobic oxidation reaction condition.     

Tungstate ions (WO4=) supported on imidazolium framework as novel and recyclable catalyst for rapid and selective oxidation of benzyl alcohols in the presence of hydrogen peroxide

Tungstate salt with imidazolium framework is found to be a recoverable and heterogeneous system favouring the highly selective oxidation of primary benzylic alcohols to corresponding aldehydes with 30% H₂O₂ as a green oxidant under neutral aqueous reaction conditions. Furthermore, in order to demonstrate the recyclability of the catalyst, it was recovered and efficiently reused in seven succeeding reaction cycles without any significant loss. The use of green solvent, very short reaction time with excellent yields and recyclability of the catalyst make this protocol highly advantageous.     

Electrocatalytic oxidation of aliphatic diols on platinum and gold Part I: Effects of chain length and isomeric position

The electrochemical reactivity of propanediol, butanediol, pentanediol, hexanediol and heptanediol, on polycrystalline platinum and gold electrodes, was studied in acid and alkaline media. The effect of the number of carbon atoms, i.e. the chain length, was observed. The apparent energies of activation were evaluated systematically and discussed in relation to the molecular structure of the different diols. In the case of the butanediol isomers, an effect of the alcohol group positions on the activation energy and reaction mechanisms was clearly shown.     

分子氧选择性氧化醇类的研究进展

综述了分子氧化剂的醇类液相催化氧化的新进展。分别介绍了均相催化、水/有机两相催化、氟两相催化和液固多相催化体系。重点讨论了精细有机合成中有广泛应用前景的绿色氧化方法。预测了均相催化剂的多相化是今后工业化发展的趋势。     

Sequential oxidation/asymmetric aldol reaction of primary alcohols by resin-supported catalysts

The sequential reaction including alcohol oxidation by TEMPO/Cu system and the asymmetric aldol reaction by peptide catalysis was realized using resin-supported catalysts. The step of oxidizing primary alcohols to the corresponding aldehydes could be dramatically enhanced through the introduction of triglycyl peptide to supported TEMPO and the method of pre-adsorbing a Cu-complex into resin beads.