异丁烯与醋酸酯化合成醋酸叔丁酯

以锆复合氧化物和大孔强酸性阳离子交换树脂为催化剂,催化异丁烯与醋酸合成了醋酸叔丁酯。采用正丁胺电位滴定法对催化剂的酸强度和酸量进行了表征。结果表明:对异丁烯与醋酸酯化反应而言,随着酸量增加,转化率增大,但酸强度增大会导致选择性下降。以异丁烯质量分数为10%的混合烃为原料,D008为催化剂,异丁烯单程转化率可达80%,醋酸叔丁酯的选择性为95.98%。     

Hydrophobic/hydrophilic effects on the titanium(IV)- catalyzed epoxidation of cyclohexene by tert-alkyl hydroperoxides: 2-methyl-1-phenyl-2-propyl hydroperoxide (MPPH) versus tert-butyl hydroperoxide (TBHP)

The epoxidation of cyclohexene in acetonitrile under argon at room temperature on a titanium(IV)-containing MCM41 silica catalyst is faster and gives a greater final yield of cyclohexene oxide when the oxygen atom donor is 2-methyl-1- phenyl-2-propyl hydroperoxide (MPPH) than when it is tert-butyl hydroperoxide. This is shown to be due to stronger retardation of the oxidation by tert-butyl alcohol (TBA) than by the alcohol derived from MPPH. The difference in retardation between these two alcohols is attributed to the greater hydrophilicity of TBA. Acetonitrile is a better solvent for this reaction than isooctane, pyridine and a variety of alcohols. These solvent effects are attributed to the hydrophilic nature of the catalyst. This revised version was published online in July 2006 with corrections to the Cover Date.     

Advanced ozone treatment of heavy oil refining wastewater by activated carbon supported iron oxide

The catalytic ozonation of heavy oil refining wastewater (HORW) was investigated over activated carbon supported iron oxides (FAC) catalysts using activated carbon (AC) as the reference. The catalyst was characterized by chemical analysis, XRD, N₂ adsorption–desorption and SEM. A significant increase in COD removal efficiency was observed in FAC + ozone compared with AC + ozone due to more hydroxyl radicals, identified by tert-butyl alcohol (TBA). The composition analysis of organic pollutant in HORW by FT-ICR MS discovered organic pollutants chain scission and oxidation process during the treatment. A great improvement of biodegradability for treated HORW had been obtained. The investigation uncovered the catalytic potential of FAC catalysts for ozonation of HORW.     

环己烷部分裂解氧化催化剂研究

用浸渍法制备了V2 O5/SiO2 、P K V/SiO2 、Cr K V/SiO2 、Mo K V /SiO2 和Fe K V/SiO2 几种固体样品 ,作为环己烷的催化裂化、氧化反应的催化剂。研究表明在V2 O5/SiO2上添加某些助剂后 ,使其脱氢、供氢、供氧中心得到改善 ,明显地抑制了深度裂解与氧化作用。Cr K V/SiO2 和Fe K V/SiO2 表面具有较强的脱氢中心和较弱的供氧中心 ,组成了适应于环己烷的部分裂化、氧化的活性中心 ,表现出较好的催化活性。     

Influence of Polar Components in the Dimerization of Isobutene

Isooctane is seen as a potential replacement for methyl tert-butyl ether (MTBE) in gasoline. Isooctane can be produced via the indirect alkylation route in two steps. Isobutene is first dimerized to isooctenes, which are then further hydrogenated to isooctane. In the dimerization a polar component is used to enhance the selectivity for diisobutenes. In this study the effects of tert-butyl alcohol (TBA), methanol and MTBE in the dimerization reaction were compared on the basis of experimental results. All the oxygenates studied induced similar effects: higher selectivity for diisobutenes and lower isobutene conversion as the oxygenate content increased and temperature decreased. The different polarity of the components causes the need for more methanol or MTBE than TBA to get the same conversion and selectivity.     

天然矿物催化氧化水中难降解有机污染物研究进展

催化氧化技术具有氧化性强、矿化效率高等优点,是去除水中难降解有机污染物最有效的处理技术之一,催化剂的应用和研究是关注的热点,天然矿物催化剂储量大、价格低,在使用成本方面具有其他催化剂无可比拟的优势。本文综述了天然矿物催化剂在Fenton法、催化臭氧氧化法、活化过硫酸盐催化氧化法处理水中难降解有机污染物的研究进展和作用机理,分析了其反应条件、处理效果和催化活性位点等,指出含有丰富的金属元素的天然矿物可作为芬顿氧化和过硫酸盐氧化的催化剂,有些天然矿物可作为金属负载载体参与氧化反应,而存在表面羟基等活性位点的天然矿物可催化臭氧氧化和芬顿氧化反应,天然矿物催化剂能明显提高Fenton、臭氧、过硫酸盐氧化难降解有机物（ROCs）的能力,在污水处理方面具有应用前景。以期能够为今后天然矿物催化剂的开发和在水处理高级氧化技术中的应用提供有益参考。     

The effects of SO2 on the oxidation of CO and propane on supported Pt and Au catalysts

The catalytic activities of Pt and Au supported on TiO₂ were compared with respect to the oxidation of CO and propane. While the Au catalysts showed higher activities for CO oxidation, the Pt catalysts were more active for propane combustion. A strong de-activation of the CO oxidation activity by SO₂ was observed only over the TiO₂-supported Au catalyst, indicating that SO₂ can block the active sites for CO oxidation over Au catalysts. The results are consistent with a model in which the perimeter sites have a special role in the CO oxidation reaction over Au catalysts.     

叔丁醇对异丁烯二聚反应选择性的影响

以强酸性阳离子交换树脂为催化剂,在高压釜内考察了加入叔丁醇(TBA)前后异丁烯(IB)二聚反应工艺条件对二异丁烯(DIB)选择性的影响.结果表明.在加入TBA后.降低了IB二聚速率.但提高了DIB选择性.当反应温度为90℃、原料中IB质量分数为17%～20%、TBA质量分数为0.6%、搅拌速率750r/min、反应3.5h后,IB的转化率约为60%,DIB的选择性可达80%左右。     

Recent topics of research and development of catalysis by niobium and tantalum oxides

Current topics of catalysts containing niobium and tantalum, especially in the field of solid acid catalysis and selective oxidation of hydrocarbons are reviewed. Hydrated niobium oxide and hydrated tantalum oxide are highly acidic. Hydrated niobium oxide is active for the hydration of ethene to ethanol, and Nb–W mixed metal oxide is more active for the reaction. Acid properties of tantalum oxide are changed by being supported on SiO₂. Ta oxide/SiO₂, prepared by the chemical reaction between tantalum alkoxide and surface hydroxyl groups of SiO₂, is active and selective for the gas phase Beckmann rearrangement of cyclohexanoneoxime to caprolactam. Niobium oxide and tantalum oxide easily react with many other oxides to form mixed metal oxide phases with complex structure. Mixed metal oxide catalysts, containing molybdenum, vanadium, certain elements together with niobium are active for the selective oxidation of hydrocarbons. Especially, the selective oxidation of propane by such mixed metal oxide catalysts has been paid attention. Additionally, recent progress of environmental catalysts, promoted by niobium and tantalum compounds, namely catalysts for the pollution abatement is reviewed.     

N-烷基-N-甲基咪唑系列离子液体中ZSM-5分子筛催化环已烷氧化反应

Heterogeneous oxidation of cyclohexane by tert-butyl hydroperoxide (TBHP) was carried out over ZSM-5 catalysts with different Si/Al ratios in ionic liquids and organic molecular solvents. Higher yield and selectivity of the desired products were found in ionic liquids than in molecular solvents. The conversion of cyclohexane exhibits a decrease from 15.8% to 10.8% with the increase of Si/Al ratio of the HZSM-5 catalyst, and all the catalysts exhibit good selectivity of monofunctional oxidation products at around 97%. The activity of catalyst is found strongly de-pendent on the alkyl chain length of ionic liquid.     

Sibunit-based catalytic materials for the deep oxidation of organic ecotoxicants in aqueous solutions. II: Wet peroxide oxidation over oxidized carbon catalysts

The influence of the surface chemical composition of carbon catalysts prepared by oxidative treatment on the basis of the Sibunit-4 carbon material of the Sibunit family on their catalytic properties in the liquid-phase oxidation of formic acid by hydrogen peroxide was studied for the first time. Pure carbon samples were found to be active in the destruction of hydrogen peroxide and the oxidation of an organic substrate, and their activity decreased with an increase in the number of carboxyl and lactone groups on the surface of a carbon catalyst. Nevertheless, the rates of such processes on carbon catalysts are lower than in the presence of even small amounts of homogeneous Fe³⁺. It was shown that carbon samples accelerate or (to the contrary) inhibit the Fe³⁺-catalyzed peroxide oxidation of an organic substance, depending on the quantitative ratio of surface carboxyl and lactone groups and Fe³⁺ ions in the reaction solution. Possible acceleration and inhibition mechanisms for peroxide oxidation on carbon catalysts are discussed. The established influence of the surface chemical properties of carbon catalysts must be taken into account in the development of catalysts and processes for the oxidative purification of industrial wastewater.     

低碳烷烃选择性氧化高分散活性位催化剂的研究进展

石油资源的过渡消耗导致化工原料短缺危机,低碳烷烃选择性氧化可以有效缓解危机并降低化工原料成本。高分散活性位催化剂在低碳烷烃选择性氧化反应中具有特殊催化作用和广阔的应用前景,在石油化工行业发展中具有巨大的潜能。基于国内外研究者在高分散活性位催化剂用于低碳烷烃选择性氧化领域的研究工作,介绍高分散活性位催化剂的制备方法,总结低碳烷烃选择性氧化高分散活性位催化剂体系,分析低碳烷烃选择性氧化反应机理。重点评述钒基、钼基和铁基高分散活性位催化剂用于低碳烷烃选择性氧化反应的催化性能及反应机理。并对高分散活性位催化剂在低碳烷烃选择性氧化中存在的问题、发展趋势和应用前景进行总结和展望。     

SBA -15负载铁基氧化物催化剂上丙烷选择氧化催化性能的研究

用等体积浸渍法制备了SBA - 15负载铁基和钾修饰的Fe基氧化物催化剂,使用紫外-拉曼光谱对催化剂结构进行表征,并评价催化剂对丙烷的选择氧化活性与选择性.结果表明,介孔结构SBA - 15对丙烷选择氧化活性优于常规的SiO2;对于负载K- Fe/SBA - 15系列催化剂,低Fe负载量时,隔离的四配位Fe氧化物是丙烷...     

Carbon-containing catalysts for the hydroprocessing of oil fractions: A review

Over the last 20 years, carbon-containing catalysts prepared using carbonized aluminum oxide and various carbon-based materials as carriers, along with metal carbides as active components, have been widely studied in the hydroprocessing of oil fractions. In this work, the properties of different groups of carbon-containing catalysts are discussed. The difficulties of using carbon-based carriers caused by their need for chemical pretreatment (oxidation and leaching), and the application of water–organic infiltrating solutions to form active catalyst components in finely dispersed form, is shown.     

Quantitative determination of the number of surface active sites and the turnover frequency for methanol oxidation over bulk metal vanadates

The present work investigates the number and nature of the surface active sites, selectivity and turnover frequency towards methanol selective oxidation of a series of bulk metal vanadates. The catalysts were synthesized through an organic route and characterized by laser Raman spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and specific surface area analysis (BET). The number of surface active sites (N_s) was determined by measuring the concentration of surface methoxy species adsorbed on the catalysts exposed to an atmosphere of 2000 ppm of methanol in helium at 100 °C. The specific activity values (TOFs) were calculated by normalizing the methanol oxidation reaction rate by the number of surface active sites probed by methanol chemisorption. The comparison of the methanol oxidation products distribution from bulk metal vanadates, pure V₂O₅ and corresponding metal oxides (NiO, MnO, etc.) strongly suggests that the metal vanadate catalysts consist of only surface vanadium oxide sites. The comparison of the TOF values demonstrated that bulk metal vanadates possess similar activity to monolayer vanadium oxide supported catalysts and are more active than bulk metal molybdates for methanol selective oxidation. Moreover, bulk metal vanadates are as active and selective as the commercial MoO₃/Fe₂(MoO₄)₃ catalysts at high methanol conversion.     

Fe-zeolites as catalysts for chemical oxidation of MTBE in water with H2O2

The heterogeneous catalytic wet oxidation of methyl tert-butyl ether (MTBE) with hydrogen peroxide, catalyzed by the iron-containing zeolites Fe-ZSM5 and Fe-Beta, was studied at ambient conditions and pH 7. The kinetics of MTBE degradation could be well-fitted to a pseudo-first-order model. Using Fe-ZSM5, the dependence of the reaction rate constant on hydrogen peroxide and catalyst concentration was determined. Furthermore, the formation and oxidation of tert-butyl alcohol and tert-butyl formate as intermediates of MTBE oxidation were studied. A comparison of the reaction rates of MTBE, trichloroethylene and diethyl ether in the Fe-ZSM5/H₂O₂ system revealed that adsorption plays a positive role for the degradation reaction.Comparing the two types of Fe-containing zeolites applied in this study, Fe-Beta showed a lower catalytic activity for H₂O₂ decomposition and also MTBE degradation. However, in terms of utilization of H₂O₂ for MTBE degradation Fe-Beta is advantageous over Fe-ZSM5. This could be explained by the stronger adsorptive enrichment of MTBE on the Fe-Beta zeolite. This study shows that Fe-containing zeolites are promising catalysts for oxidative degradation of MTBE by H₂O₂.     

Selective oxidation of light alkanes over hydrothermally synthesized Mo-V-M-O (M=Al, Ga, Bi, Sb, and Te) oxide catalysts

Selective oxidations of ethane to ethene and acetic acid and of propane to acrylic acid were carried out over hydrothermally synthesized Mo-V-M-O (M=Al, Ga, Bi, Sb, and Te) complex metal oxide catalysts. All the synthesized solids were rod-shaped crystallites and gave a common XRD peak corresponding to 4.0 Å d-spacing. From the different XRD patterns at low angle region below 10° and from the different shape of the cross-section of the rod crystal obtained by SEM, the solids were classified into two groups: Mo-V-M-O (M=Al, possibly Ga and Bi) and Mo-V-M-O (M=Sb, and Te). The former catalyst was moderately active for the ethane oxidation to ethene and to acetic acid. On the other hand the latter was found to be extremely active for the oxidative dehydrogenation. The Mo-V-M-O (M=Sb, and Te) catalysts were also active for the propane oxidation to acrylic acid. It was found that the grinding of the catalysts after heat-treatment at 600°C in N₂ increased the conversions of propane and enhanced the selectivity to acrylic acid. Structural arrangement of the catalytic functional components on the surface of the cross-section of the rod-shaped catalysts seems to be important for the oxidation activity and selectivity.     

Catalytic Combustion of Methyl Tert-Butyl Ether on Rh/??-Al2O3 and Rh/??-Al2O3?CCeO2 Catalysts: Effects of Thermal Treatments, Cerium Oxide and Particle Size

The effects of activation pretreatments, Rh particle size and content of cerium oxide on Rh/??-Al₂O₃ catalysts for the oxidation of methyl tert-butyl ether (MTBE) were investigated. Three different conditions were used for the activation of the catalysts: (1) with air flow, (2) using a mixture of air and MTBE, and (3) by hydrogen reduction followed by oxidation with air. On Rh/??-Al₂O₃ catalyst the thermal pretreatments are of great importance for the MTBE oxidation. However, on Rh/??-Al₂O₃?CCe1 catalyst, the total combustion of MTBE was reached at a temperature of 200???C lower than that obtained with the Rh/??-Al₂O₃ catalyst at whatever thermal treatment applied. A Rho/Rh^??+ and Ce³⁺/Ce⁴⁺ species were identified by XPS suggesting that they are the responsible of the high activity showed by the Rh/??-Al₂O₃?CCe1 catalyst. A particle size effect for MTBE oxidation was observed on Rh/??-Al₂O₃ catalysts, large Rh particles are more active than the small ones.     

New approaches to designing selective oxidation catalysts: Au/C a versatile catalyst

Selective oxidation is of key importance in the synthesis of chemical intermediates. For many years a number of oxides and supported metal catalysts have been used. The key questions involved in the design of selective oxidation catalysts are discussed in the initial part of this paper. One of the most exciting recent developments in the field of selective oxidation has been the discovery that supported gold catalysts are active. The second part of the paper discusses Au/C catalysts, which are shown to be particularly versatile for oxidation reactions. Four examples of selective oxidation are described using molecular oxygen as oxidant: (a) selective oxidation of glycerol to glycerate in the presence of base; (b) the oxidation of cyclohexane to cyclohexanol and cyclohexanane in the presence of a radical initiator; (c) the oxidation of hydrogen to hydrogen peroxide, and (d) the oxidation of benzyl alcohol to benzaldehyde under solvent free conditions. In contrast, the Au/C catalysts are not active for oxidation of carbon monoxide at ambient temperature. These examples demonstrate that there exists a rich potential for Au/C as a selective oxidation catalyst and that research efforts should now be focussed on selective oxidation using supported gold catalysts.     

Keggin型杂多酸盐催化氧化甲苯制备苯甲醛

在以叔丁基过氧化氢(TBHP)为氧化剂,乙腈为溶剂的条件下,利用Keggin型Co3H2PV2Mo10O40杂多酸盐为催化剂催化氧化甲苯制备了苯甲醛。用红外光谱分析(IR)、X射线衍射(XRD)方法对催化剂进行了表征。实验表明,在90℃反应6 h,甲苯转化率为28.5%,苯甲醛的选择性达55.5%。