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1.
醇在钒基催化剂上的氧化 总被引:1,自引:0,他引:1
Wimonrat TRAKARNPRUK Piyanoot HOONSART 《催化学报》2007,28(4):290-292
以过氧化叔丁醇作为氧化剂,研究了醇类(苯甲醇、1-苯基乙醇和环己醇)在钒基催化剂上的氧化反应.制备了含苯磷二酚配体或吡嗪-2-羧酸酯配体的钒配合物,并运用傅里叶变换红外光谱、核磁共振谱、紫外-可见光谱及元素分析对其进行了表征.考察了溶剂对该类反应的影响.发现在甲苯溶剂中进行氧化反应时,苯甲醇被氧化成苯甲醛而不会被深度氧化为苯甲酸;而在乙腈溶剂中,苯甲醛和苯甲酸均有生成.此外,对不同钒磷氧化物的催化活性进行了比较,结果表明,在乙腈溶剂中的产品收率比在甲苯溶剂中高. 相似文献
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The vanadium phosphorous oxide (VPO) catalysts, supported on mesoporous hexagonal molecular sieves (HMS) with different vanadium loadings, were prepared by precipitation method on organic phase. Techniques such as XRD, BET and SEM, were used for characterization of the catalyst. The bulk VPO catalyst contains vanadyl pyrophosphate phase ((VO)2P2O7), and a small amount of VOPO4. The high surface area, large pore volume and pore size of HMS in VPO/HMS samples, provide an excellent dispersion of same phase of VPO compound on the support surface. Oxidation of various alcohols was studied in the liquid phase over VPO/HMS catalyst, using tert‐butylhydroperoxide (TBHP) as an oxidant. The activity of VPO/HMS samples were considerably increased with respect to bulk VPO catalyst. At 90 °C, the obtained activities were 0.567 and 6.545 gpro.g?1VPOh?1 over the bulk VPO and 20 wt% VPO/HMS catalysts, respectively. The effects of substrates, reaction time, reaction temperature, solvents, catalyst recycling and leaching of VPO in liquid phase reaction were also investigated. The following order has been observed for the percentage of conversions of alcohols: Benzylic alcohol > Secondary alcohol ~ Primary alcohol. The kinetic of benzyl alcohol oxidation using excess TBHP over VPO/HMS catalyst was investigated at temperatures of 27, 60 and 90 °C, and followed a pseudo‐first order with respect to benzyl alcohol. 相似文献
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The selective oxidation of styrene under heterogeneous catalyzed conditions delivers environmentally friendly paths for the production of benzaldehyde, an important intermediate for the synthesis of several products. The present review explores heterogeneous catalysts for styrene oxidation using a variety of metal catalysts over the last decade. The use of several classes of supports is discussed, including metal–organic frameworks, zeolites, carbon materials and silicas, among others. The studied catalytic systems propose as most used oxidants tert-butyl hydroperoxide, and hydrogen peroxide and mild reaction conditions. The reaction mechanism proceeds through the generation of an intermediate reactive metal–oxygen species by catalyst-oxidant interactions. Overall, most of the studies highlight the synergetic effects among the metal and support for the activity and selectivity enhancement. 相似文献
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Lara S. Escandón Salvador Ordóez Fernando V. Díez Herminio Sastre 《Reaction Kinetics and Catalysis Letters》2002,76(1):61-68
The combustion of ammonia in air over different conventional oxidation catalysts has been studied in the present work. The final oxidation product is NO, although N2O is also formed at intermediate temperatures. The environmentally desirable product, N2, is only appreciably yielded over iron oxides catalysts. 相似文献
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按文献方法制备了3种八面体MnO6分子筛催化剂K-OMS-2、H-K-OMS-2和Cu-OMS-2,用SEM和XRD测试技术表征了它们的结构和组成。 考察了这3种催化剂对用氧气选择性氧化醇为相应的醛或酮的催化作用,研究了采用不同OMS-2在离子液体[bmim]PF6中反应时间和反应温度对催化反应的影响。 其中H-K-OMS-2对苄醇和烯丙醇氧化的转化率和选择性均超过90%。 催化剂和离子液体可分别用萃取法和减压蒸馏法从反应体系中回收,其中减压蒸馏法回收循环使用效果较好。 相似文献
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Selective Oxidation of CO in Excess H2 over Ru/Al2O3 Catalysts Modified with Metal Oxide 总被引:1,自引:0,他引:1 下载免费PDF全文
Xirong Chen Hanbo Zou Shengzhou Chen Xinfa Dong Weiming Lin 《天然气化学杂志》2007,16(4):409-414
The Ru/Al_2O_3 catalysts modified with metal oxide(K_2O and La_2O_3)were prepared via incipient wetness impregnation method from RuCl_3·nH_2O mixed with nitrate loading on Al_2O3 support. The activity of catalysts was evaluated under simulative conditions for the preferential oxidation of CO (CO-PROX)from the hydrogen-rich gas streams produced by reforming gas,and the performances of catalysts were investigated by XRD and TPR.The results showed that the activity temperature of the modified catalysts Ru-K_2O/Al_2O3 and Ru-La_2O_3/Al_2O_3 were lowered approximately 30℃compared with pure Ru/Al_2O_3,and the activity temperature range was widened.The conversion of CO on Ru-K_2O/Al_2O_3 and Ru-La_2O_3/Al_2O_3 was above 99% at 140-160℃,suitable to remove CO in a hydrogen-rich gas and the selectivity of Ru-La_2O_3/Al_2O_3 was higher than that of Ru-K_2O/Al_2O_3 in the active temperature range. Slight methanation reaction was detected at 220℃and above. 相似文献
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Christian Hess Prof. Dr. 《Chemphyschem》2009,10(2):319-326
Controlled synthesis based on spectroscopic characterization, structure, and catalytic performance of mesoporous silica SBA‐15‐supported vanadium oxide model catalysts (see TEM image) are reviewed. The effect of water on the structure and dispersion of highly dispersed vanadium oxide is discussed in the light of recent results in multiple in situ spectroscopy.
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KANG Qiao-xiang YANG Zhi-wang LI Cui-lin MA Heng-chang GUO Zhen WANG You-peng XU Da-hai LEI Zi-qiang 《合成化学》2004,12(Z1)
Oxidation of alcohols to the corresponding aldehydes or ketones is one of the most fundamental reactions in organic chemistry [1,2]. Some of the products of the oxidation exhibit an important role in the organic synthesis as well as pharmaceutical synthesis. In most reactions, the lanthanide complexes show satisfied catalytic activities for some compounds. Furthermore, there has been increasing interest in the lanthanide complexes and several reports have appeared in the literature [3, 4]. But the exploitation of these complexes for the oxidation of some organic substrates has been limited. Here we reported a method for the preparation and the catalytic properties as well as the recycling of lanthanide complexes in oxidation of alcohols.The synthetic procedure for the polymer supported lanthanide complexes is shown as following(scheme 1):●-NH2+CICH2COOH(C2Hs)3N→●-NHCH2COOHM=Ce(Ⅲ), Tb(Ⅲ), Sm(Ⅲ)scheme 1The oxidation of benzyl alcohol was carried out in the presence of iodosylbenzene by the polymer supported Ce(Ⅲ), Tb(Ⅲ) and Sm(Ⅲ) catalysts at 80℃ for 4.0h, the yields of benz-aldehyde are as following (table 1):Table 1 Oxidation of benzyl alcohol with the supported catalysts**Reaction condition: benzyl alcohol 0.1 mmol, iodosylbenzene 0.15mmol,catalyst 0.2mg, 80℃ for 4.0h in 1,2-dichloroethane.It can be seen from the table that the Tb(Ⅲ) complex shows higher catalytic activity for the oxidation of benzyl alcohol. Further investigation is now being carded on to optimize the results. 相似文献
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Maximizing the Number of Interfacial Sites in Single‐Atom Catalysts for the Highly Selective,Solvent‐Free Oxidation of Primary Alcohols 下载免费PDF全文
Tianbo Li Dr. Fei Liu Yan Tang Dr. Lin Li Prof. Shu Miao Yang Su Dr. Junying Zhang Prof. Jiahui Huang Hui Sun Prof. Masatake Haruta Prof. Aiqin Wang Prof. Botao Qiao Prof. Jun Li Prof. Tao Zhang 《Angewandte Chemie (International ed. in English)》2018,57(26):7795-7799
The solvent‐free selective oxidation of alcohols to aldehydes with molecular oxygen is highly attractive yet challenging. Interfacial sites between a metal and an oxide support are crucial in determining the activity and selectivity of such heterogeneous catalysts. Herein, we demonstrate that the use of supported single‐atom catalysts (SACs) leads to high activity and selectivity in this reaction. The significantly increased number of interfacial sites, resulting from the presence of individually dispersed metal atoms on the support, renders SACs one or two orders of magnitude more active than the corresponding nanoparticle (NP) catalysts. Lattice oxygen atoms activated at interfacial sites were found to be more selective than O2 activated on metal NPs in oxidizing the alcohol substrate. This work demonstrates for the first time that the number of interfacial sites is maximized in SACs, providing a new avenue for improving catalytic performance by developing appropriate SACs for alcohol oxidation and other reactions occurring at metal–support interfacial sites. 相似文献
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Revealing the Active Species for Aerobic Alcohol Oxidation by Using Uniform Supported Palladium Catalysts 下载免费PDF全文
Pingyu Xin Prof. Dr. Jia Li Yu Xiong Xi Wu Dr. Juncai Dong Dr. Wenxing Chen Prof. Dr. Yu Wang Prof. Dr. Lin Gu Prof. Dr. Jun Luo Dr. Hongpan Rong Prof. Dr. Chen Chen Prof. Dr. Qing Peng Prof. Dr. Dingsheng Wang Prof. Dr. Yadong Li 《Angewandte Chemie (International ed. in English)》2018,57(17):4642-4646
The active species in supported metal catalysts are elusive to identify, and large quantities of inert species can cause significant waste. Herein, using a stoichiometrically precise synthetic method, we prepare atomically dispersed palladium–cerium oxide (Pd1/CeO2) and hexapalladium cluster–cerium oxide (Pd6/CeO2), as confirmed by spherical‐aberration‐corrected transmission electron microscopy and X‐ray absorption fine structure spectroscopy. For aerobic alcohol oxidation, Pd1/CeO2 shows extremely high catalytic activity with a TOF of 6739 h?1 and satisfactory selectivity (almost 100 % for benzaldehyde), while Pd6/CeO2 is inactive, indicating that the true active species are single Pd atoms. Theoretical simulations reveal that the bulkier Pd6 clusters hinder the interactions between hydroxy groups and the CeO2 surface, thus suppressing synergy of Pd‐Ce perimeter. 相似文献
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A metal-free aerobic oxidation of benzylic alcohols to the corresponding benzylaldehyde derivatives was accomplished using proton ionic liquids (pyridium nitrate) as catalyst in a nonsolvent system with excellent conversion and selectivity. The catalyst could be recycled with no other polluted emission in this reaction procedure. 相似文献
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甲醛具有致畸和致癌性,是主要的室内污染物。催化氧化法甲醛转化效率高,没有二次污染,相关研究日益受到关注。本文详细介绍了贵金属和非贵金属两类主要的甲醛氧化催化剂,探讨了活性组分、载体、催化剂助剂等催化剂组成对于其理化性质和反应性能的影响规律,讨论了制备方法、反应物中的水含量等因素对于催化反应的影响,分析了催化剂失活的主要因素。研究表明,催化剂表面活性氧、表面羟基、氧空位数量以及对反应物的吸脱附和存储能力是影响催化活性的关键因素。贵金属催化剂,特别是Pt催化剂具有较好的催化性能,可在较低温度实现甲醛充分转化;非贵金属催化剂具有可变价态,通过催化剂的合理设计可以具有足够的催化活性,其原料资源丰富,价廉易得,应用前景广阔。 相似文献
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Mg-Fe尖晶石复合氧化物对苯乙烯选择氧化反应的催化性能 总被引:8,自引:0,他引:8
研究了以H2O2为氧化剂时Mg-Fe尖晶石复合氧化物催化剂对苯乙烯选择氧化制苯甲醛反应的催化性能.结果表明,非化学计量比的Mg-Fe尖晶石复合氧化物催化剂的活性优于纯MgFe2O4尖晶石相,苯甲醛产率达到20%左右.在非化学计量比的Mg-Fe尖晶石复合氧化物中掺入适量的Al3+后,可进一步提高催化活性,苯甲醛最高产率达到33.4%.催化剂表征数据揭示,非化学计量比的Mg-Fe和Mg-Fe-Al复合氧化物催化剂是由纳米尺度的铁酸盐尖晶石和α-Fe2O3微晶相构成的.除了非化学计量比尖晶石具有较多的缺陷结构外,α-Fe2O3微晶相的存在也可能是造成非化学计量比催化剂活性高的原因之一. 相似文献
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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. 相似文献