复合金属氧化物的制备及其光催化羟基化制备苯二酚的性能研究

采用溶胶-凝胶法制备了负载Fe-Al的纳米TiO2复合金属氧化物Fe-TiO2和Fe-Al-TiO2;采用XRD、TEM和XPS对材料的结构特点和形貌进行表征,研究了材料的光催化羟基化苯酚制备邻苯二酚和对苯二酚的性能;结果表明Fe-TiO2和Fe-Al-TiO2在紫外光照射下均具有良好的光催化羟基化性能和催化稳定性。苯二酚的最高收率为41%。

纳米TiO_2、NiO和CuO的制备、表征及催化苯酚羟基化反应研究

分别采用均匀沉淀法和固相法合成纳米级的TiO2,NiO和CuO颗粒,用XRD,TEM等对其结构和形貌进行了表征,用纳米TiO2,NiO和CuO为催化剂,对苯酚羟基化反应的活性进行研究。结果表明,纳米TiO2,NiO和CuO颗粒催化苯酚羟基化反应具有较好的催化活性,苯酚的转化率分别达到25.3%,28.3%和27.5%。

葡枝根霉NG0305酶催化甾体C_(11)α羟基化的研究

应用本实验室保藏的葡枝根霉RhizopusstoloniferNG0 30 5对甾体化合物烯睾丙内酯 (3 oxo 4 ,6 diene Pregna 17 alpha hydroxy 2 1 carboxylicacidgama lactone)进行酶催化C1 1 α 羟基化反应的研究。研究结果表明 ,菌体培养的碳源供应对菌体所产羟化酶的活力有重要影响。采用葡萄糖和淀粉组合碳源 ,并加入适量的黑曲霉糖化酶的方式 ,解决了葡萄糖抑制的问题 ,并缩短了菌体培养反应时间 ,得到高羟化转化率。酶转化反应 88h后 ,提取吸附在菌丝球内的产物 ,应用液相色谱测定 ,结果表明C1 1 α 羟基化转化率达到了 5 3 0 %。

苯酚羟基化制苯二酚的催化剂研究新进展

国内迄今尚未有先进、成熟的苯酚羟基化生产苯二酚的工业化技术出现,其主要原因在于工业羟基化催化剂研发的滞后。综述了苯酚过氧化氢羟基化反应催化剂的研究现状,分析了复合金属氧化物、杂原子取代的分子筛和杂多酸盐等几类催化剂的性能和特点,指出催化剂的发展趋势是从简单、均相的形式向复合、非均相的载体形式发展,其中铁系复合型催化剂是最经济实用的羟基化催化剂,可成为苯酚羟基化工业催化剂研究的方向。

对叔丁基苯酚羟基化反应的研究

采用Fe(OH)3+有机络合剂+H2O2系统,对羟基化法由对叔丁基苯酚(PTBP)制备对叔丁基邻苯二酚(4-TBC)的反应进行了研究。探讨了反应时间、反应温度、催化剂用量、n(H2O2)∶n(PTBP)、溶剂类型等因素对反应的影响。实验结果表明,溶剂类型和n(H2O2)∶n(PTBP)对催化剂的活性影响较大。在PTBP0.80g、n(H2O2)∶n(PTBP)=1.0、乙腈水溶液(乙腈与水体积比2∶1)30mL、Fe(OH)30.05g、邻苯二酚0.05g、反应温度55℃、反应时间60min的条件下,PTBP转化率可达18.5%,4-TBC选择性达89.2%。对反应机理的探索表明,Fe3++H2O2系统中的羟基自由基(.OH)不能对PTBP进行羟基化反应;Fe3++有机络合剂+H2O2系统中以活性铁氧络合物为氧化剂,与有机酚类反应物有良好的反应亲和力,能顺利完成PTBP的羟基化反应。

(1R,2S,3R,4S,6R)-2,3,4-三羟基-2-(苄氧羰基氨基)-环己烷甲酸苄酯的高立体选择性合成

多羟基环己基手性β-氨基酸及其衍生物具有重要的药物、生物和合成用途.本文对从内消旋cis-1,2,3,6-四氢邻苯二甲酸酐经去对称化得到的内酯关键中间体(2)的绝对构型进行了确定,并通过邻二羟基化和内酯开环,经两步反应以45%的产率从化合物(2)高立体选择性地合成了光学活性的(1R,2S,3R,4S,6R)-2,3,4-三羟基-2-(苄氧羰基氨基)-环己烷甲酸苄酯(6).

Realizing efficient electrochemical oxidation of 5-hydroxymethylfurfural on a freestanding Ni(OH)_(2)/nickel foam catalyst

With the continuous improvement of solar energy production capacity,how to effectively use the electricity generated by renewable solar energy for electrochemical conversion of biomass is a hot topic.Electrochemical conversion of 5-hydroxymethylfurfural(HMF)to biofuels and value-added oxygenated commodity chemicals provides a promising and alternative pathway to convert re-newable electricity into chemicals.Although nickel-based eletrocatalysts are well-known for HMF oxidation,their relatively low intrinsic activity,poor conductivity and stability still limit the poten-tial applications.Here,we report the fabrication of a freestanding nickel-based electrode,in which Ni(OH)_(2) species were in-situ constructed on Ni foam(NF)support using a facile ac-id-corrosion-induced strategy.The Ni(OH)2/NF electrocatalyst exhibits stable and efficient electro-chemical HMF oxidation into 2,5-furandicarboxylic acid(FDCA)with HMF conversion close to 100% with high Faraday efficiency.In-situ formation strategy results in a compact interface between Ni(OH)_(2) and NF,which contributes to good conductivity and stability during electrochemical reac-tions.The superior performance benefits from dynamic cyclic evolution of Ni(OH)_(2) to NiOOH,which acts as the reactive species for HMF oxidation to FDCA.A scaled-up device based on a continu-ous-flow electrolytic cell was also established,giving stable operation with a high FDCA production rate of 27 mg h^(-1)cm^(−2).This job offers a straightforward,economical,and scalable design strategy to design efficient and durable catalysts for electrochemical conversion of valuable chemicals.

钛硅酸盐分子筛TS－2的合成

在无碱金属离子存在下，采用四丁基氢氧化铵及１，６－己二胺模板剂，全面探讨以硅溶胶、正硅酸乙酯硅源，硫酸钛、氯化钛及钛酸四丁酯为钛源，在异而醇或过氧化氢的保护下合成ＴＳ－２沸石．对产品作了必要的物性表征，深入研究了ＴＳ－２沸石催化羟基化氧化反应条件，得到了较好的结果．

高附加值萘二酚类中间体的合成与应用进展

萘二酚类中间体的传统合成工艺具有操作简单和工业化程度高等优点,但存在废酸排放量大、后处理工艺复杂、成本高和环境污染严重等问题,近年来有被绿色合成工艺逐步替代的趋势。本文回顾了以磺化碱熔法和硝化还原法为主的传统合成方法;简述了用微藻类微生物、重组酵母以及多种结构的加氧酶代谢转化的生物转化法和以强酸、生物酶以及有机金属络合物作为催化剂的直接催化羟基化法等新兴绿色合成工艺。着重介绍了1,6-二羟基萘(又称为1,6-萘二酚)的合成工艺进展,特别是在过氧化氢存在下,采用酸催化剂,如用强酸氢氟酸和五氟化锑催化以及用氟锑磺酸、三氟化硼和氢氟酸等直接进行的催化羟基化反应。同时还综述了萘二酚化合物在染料、医药、催化及电池等领域的典型应用情况。最后指出了生物转化法及催化羟基化法制备萘二酚的改进方向是提高反应的收率及萘的转化率,以达到大规模工业化生产的水平;并对萘二酚类中间体应用领域的拓展进行了展望,指出其向精细化、高附加值的医药及材料方向发展的趋势。

Highly selective production of phenol from benzene over mesoporous silica-supported chromium catalyst:Role of response surface methodology in optimization of operating variables

A Cr/SBA-16 catalyst was prepared using Cr（NO3）3 as a precursor and mesoporous silica SBA-16 as a support via a simple impregnation method. The catalyst was characterized using wide-angle X-ray diffraction （XRD）, low-angle XRD, N2 adsorption-desorption, transmission electron microscopy, and ultraviolet-visible spectroscopy. The catalyst activity was investigated in the direct bydroxylation of benzene to phenol using H2O2 as the oxidant. Various operating variables, namely reaction temperature, reaction time, amount of H2O2, and catalyst dosage, were optimized using central composite design combined with response surface methodology （RSM）. The results showed that the correla- tion between the independent parameters and phenol yield was represented by a second-order polynomial model. The high correlation coefficient （R2）, i.e., 0.985, showed that the data predicted using RSM were in good agreement with the experimental results. The optimization results also showed that high selectivity for phenol was achieved at the optimized values of the operating variables： reaction temperature 324 K, reaction time 8 h, H2O2 content 3.28 mL, and catalyst dosage 0.09 g. This study showed that RSM was a reliable method for optimizing process variables for benzene hydroxylation to phenol.

Oxidation of 2,5‐bis(hydroxymethyl)furan to 2,5‐furandicarboxylic acid catalyzed by carbon nanotube‐supported Pd catalysts

The selective oxidation of 2,5‐bis(hydroxymethyl)furan(BHMF)in this work was proven as a promising route to produce 2,5‐furandicarboxylic acid(FDCA),an emerging bio‐based building‐block with wide application.Under ambient pressure,the modified carbon nanotube‐supported Pd‐based catalysts demonstrate the maximum FDCA yield of 93.0%with a full conversion of BHMF after 60 min at 60°C,much superior to that of the traditional route using 5‐hydroxymethylfurfural(HMF)as substrates(only a yield of 35.7%).The participation of PdH_(x) active species with metallic Pd can be responsible for the encouraging performance.Meanwhile,a possible reaction pathway proceeding through 2,5‐diformylfuran(DFF)and 5‐formyl‐2‐furancarboxylic acid(FFCA)as process intermediates is suggested for BHMF route.The present work may provide new opportunities to synthesize other high value‐added oxygenates by using BHMF as an alternative feedstock.

Mesoporous polyoxometalate-based ionic hybrid as a highly effective heterogeneous catalyst for direct hydroxylation of benzene to phenol

Self‐assembled mesoporous polyoxometalate‐based ionic hybrid catalyst,[PxyDim]2.5PMoV2,was prepared by combining p‐xylene‐tethered diimidazole ionic liquid[PxyDim]Cl2with Keggin‐structured V‐substituted polyoxometalate H5PMo10V2O40.The obtained hybrid was shown to be a mesostructured and hydrophobic material with good thermal stability.In the H2O2‐based hydroxylation of benzene to phenol,the hybrid showed extraordinary catalytic activity and rate,and quite stable reusability.The unique hydrophobic properties and mesoporous structure of the hybrid were responsible for its excellent catalytic performance.

Hydroxylation of Benzene with Hydrogen Peroxide over Highly Efficient Molybdovanadophosphoric Heteropoly Acid Catalysts

Keggin type molybdovanadophosphoric heteropoly acids, H3＋nPMo12-nVnO40（n=1-3）, were prepared by a novel environmentally benign method, and their catalytic performances were evaluated via hydroxylation of benzene to phenol with hydrogen peroxide as oxidant in a mixed solvent of glacial acetic acid and acetonitrile. Various reaction parameters, such as reaction time, reaction temperature, ratio of benzene to hydrogen peroxide, concentration of aqueous hydrogen peroxide, ratio of glacial acetic acid to acetonitrile in solvent and catalyst con- centration, were changed to obtain an optimal reaction conditions. H3＋nPMo12-nVnO40（n=1-3） are revealed to be highly efficient catalyst for hydroxylation of benzene. In case of H5PMo10V2O40, a conversion of benzene of 34.5% with the selectivity of phenol of 100% can be obtained at the optimal reaction conditions.

Model Study on a Submerged Catalysis/Membrane Filtration System for Phenol Hydroxylation Catalyzed by TS-1

This ranearch is focused on the, develonment of a simnle design model of the submerged catalysis/membrane filtration （catalysis/MF） system for phenol hydroxylation over TS-1 based on the material balance of the phenol under steady state and the reported kinetic studies. Based on the developed model, the theoretical phenol Conversions at steady state could be calculated using the kinetic parameters obtained from the previous batch experiments. The theoretical conversions are in good agreement with the experimental data obtained in the submerged catalysis/MF system within relative error of ±5%. The model can be used to determine the optimal experimental conditions to carry out the phenol hydroxylation over TS-1 in the submerged catalysis/MF system.

Synergistic Catalytic Action of Cobalt(Ⅱ) Hydroxamates and N-Hydroxyphthalimide in the Aerobic Oxidation of p-Xylene

The catalytic performance of a series of cobalt(Ⅱ) hydroxamates (CoL2) and the synergistic catalytic action of the cobalt complexes combined with N-hydroxyphthalimide (NHPI) in the aerobic oxidation of p-xylene to p-toluic acid (PTA) were investigated. The results showed that the existing synergistic action in the catalytic oxidation can shorten the induction period of the radical reaction and improve the yield of PTA.

A “Green” Cyclohexanone Oxidation Route Catalyzed by Hollow Titanium Silicate Zeolite for Preparing ε-Caprolactone,6-Hydroxyhexanoic Acid and Adipic Acid

Hollow titanium silicalite （HTS） molecular sieve has been synthesized, and information on its structure, physico- chemical characterization, as well as surface property was investigated by a host of analytical methods, such as XRF, XRD, low-temperature N2 adsorption/desorption, TEM, FT-IR, UV-Vis, 29Si MAS NIVIR, and XPS techniques. The characterization results suggest that HTS zeolite has a special hollow crystal structure and its mesopore volume is larger than that of TS-1 zeolite. The titanium species in this zeolite are composed of the framework tetrahedral Ti （IV） ions and extra-framework octahedral Ti （IV） ions, which tend to disperse into its bulk phase. This zeolite material also has been applied to catalyze the cyclohexanone oxidation process, and the products are not completely consistent with those results obtained by using TS-1 zeolite, which might be caused by their difference in pore structure and pore volume, especially the mesopore volume. Cy- clohexanone oxidation catalyzed by HTS zeolite is a representative consecutive reaction, the main target products of which are e-caprolactone, 6-hydroxyhexanoic acid and adipic acid. The effect of H202/cyclohexanone mole ratio on the cyclohexa- none conversion, the total target product selectivity, the distribution of three target products selectivity and their variations along with reaction time is also researched and analyzed, which indicate that HTS zeolite shows a high performance for the Baeyer-Villiger reaction of cyclohexanone and catalytic oxidation of 6-hydroxyhexanoic acid under mild conditions, and the quantity of active surface titanium species as well as the pore structure and mesopore volume controlling the mass diffusion rate are the key factors determining the catalytic activity of HTS zeolite and product selectivity.

Advances in Study on Catalysts for Phenol Synthesis via Catalytic Hydroxylation of Benzene in China

Synthesis of phenol via direct hydroxylation of benzene as a typical reaction of atomic economy has attracted extensive attention worldwide and has also become an actively investigated domain in China. This article refers to the recent domestic advances in study on phenol synthesis via hydroxylation of benzene from the viewpoint of catalysts, and considers the TS-1/H2O2 and FeZSM-5/N2O catalytic systems to be promising ones with good prospects for commercialization along with some suggestions on future research work.

Copper‐doped nickel oxyhydroxide for efficient electrocatalytic ethanol oxidation

Rational design of low‐cost and efficient electrocatalysts for ethanol oxidation reaction(EOR)is imperative for electrocatalytic ethanol fuel cells.In this work,we developed a copper‐doped nickel oxyhydroxide(Cu‐doped NiOOH)catalyst via in situ electrochemical reconstruction of a NiCu alloy.The introduction of Cu dopants increases the specific surface area and more defect sites,as well as forms high‐valence Ni sites.The Cu‐doped NiOOH electrocatalyst exhibited an excellent EOR performance with a peak current density of 227 mA·cm^(–2)at 1.72 V versus reversible hydrogen electrode,high Faradic efficiencies for acetate production(>98%),and excellent electrochemical stability.Our work suggests an attractive route of designing non‐noble metal based electrocatalysts for ethanol oxidation.

Investigation of N-（Hydroxylethyl）pyrrolidone Dehydration over REOx-doped Nano-ZrO2 Catalyst

Catalyst plays an important role in the dehydration of N-（hydroxylethyl）pyrrolidone （NHP） to prepare N-vinyl-pyrrolidone （NVP）. At present, NVP yield is only about 30% on commercial ZrO2 catalyst. A coupled precipitation and solid dispersion technique was designed to prepare the nano-ZrO2 catalyst, in which rare earth metal oxides （REOx） was used as electronic promoter. The results indicated that the catalyst doped REOx （S-1.0） exhibits the optimum performance of NHP dehydration at moderate conditions. NHP conversion and NVP selectivity are respectively 97.0%, 82.3%. Of special interest is that the indexes of the catalyst （S-1.0-1.0） are up to 98.4% and 89.2% respectively. Furthermore, this catalyst bears the good stability. It means that nano-ZrO2 doped REOx catalyst might be a potential commercial catalyst for the NHP dehydration.

Synthesis of α-hydroxy ketones by copper（Ⅰ）-catalyzed hydration of propargylic alcohols: CO2 as a cocatalyst under atmospheric pressure

Inexpensive and efficient Cu(Ⅰ) catalysis is reported for the synthesis of α-hydroxy ketones from propargylic alcohols, CO2, and water via tandem carboxylative cyclization and nucleophilic addition reaction. Notably, hydration of propargylic alcohols can be carried out smoothly under atmospheric CO2 pressure, generating a series of α-hydroxy ketones efficiently and selectively. This strategy shows great potential for the preparation of valuable α-hydroxy ketones by using CO2 as a crucial cocatalyst under mild conditions.