纳米Ce1—xMnxO2催化剂上乙醇催化氧化发光研究

研究了纳米Ce_1—xMn_xO₂上乙醇催化氧化发光特性, 重点考察了反应温度和催化剂组成(Ce/Mn比)对发光强度的影响规律. 为研究催化发光机理, 在相近的反应条件下考察了纳米Ce_1—xMn_xO₂上乙醇催化氧化反应的活性和选择性. 结果表明: 催化发光强度与催化反应中生成CH₃CHO的产率有很好的顺变关系, 表明CH₃CHO是导致C₂H₅OH分子在纳米Ce_1—xMn_xO₂催化剂上氧化发光的“活性分子”.     

纳米Ce1—xMnxO2催化剂上乙醇催化氧化发光研究

研究了纳米Ce_1—xMn_xO₂上乙醇催化氧化发光特性, 重点考察了反应温度和催化剂组成(Ce/Mn比)对发光强度的影响规律. 为研究催化发光机理, 在相近的反应条件下考察了纳米Ce_1—xMn_xO₂上乙醇催化氧化反应的活性和选择性. 结果表明: 催化发光强度与催化反应中生成CH₃CHO的产率有很好的顺变关系, 表明CH₃CHO是导致C₂H₅OH分子在纳米Ce_1—xMn_xO₂催化剂上氧化发光的“活性分子”.     

预处理对TS-1/硅藻土催化剂性能的影响

以固定床催化苯酚羟基化制苯二酚为目标反应，制备了负载型TS-1/硅藻土催化剂。运用FT-IR、XRD、UV-Vis、ICP-AES和NH₃-TPD等表征手段，研究了预处理介质对TS-1/硅藻土催化剂物化和催化性能的影响。研究表明，用KAc、NaAc、NH₄Ac、NH₄Cl和HNO₃水溶液预处理催化剂后，对TS-1分子筛的骨架结构和骨架Ti的存在无明显影响，但可脱除部分非骨架TiO₂，使催化剂的表面     

CO预处理对CuO/γ-Al2O3催化剂性能的影响

采用XRD，TPR，CO吸附in-situ IR，CO氧化反应等对CuO/γ-Al₂O₃催化剂经CO处理前后的结构、组成和催化性能进行了研究。结果表明，经CO在250 ℃下处理1 h后CuO/γ-Al₂O₃催化剂中出现了分散态Cu⁺物种，该物种的产生使催化剂的活性明显提高。     

CO2选择氧化低碳烷烃的研究进展

本文以低碳烷烃的选择催化氧化反应为对象，对几种CO₂选择氧化低碳烷烃的反应工艺进行了归纳总结，重点分析讨论了催化氧化反应中CO₂作为氧化剂的作用机制，并提出了研究展望。     

磁性纳米Pd/Fe3O4催化剂的制备及其在Heck反应中的应用

通过使用聚乙烯吡咯烷酮作为稳定剂,合成了磁性Pd/Fe₃O₄纳米颗粒催化剂。对该催化剂进行粉末X射线衍射、透射电子显微镜、感应耦合等离子体和磁性表征。将Pd/Fe₃O₄催化剂用于Heck反应,检测其催化性能。测试结果表明Pd纳米颗粒负载在Fe₃O₄纳米颗粒上,而且催化剂的尺寸<20 nm,并在Heck反应中表现了极好的催化性能。此外,催化剂可以通过磁场回收利用, 且催化活性没有显著的降低。     

镍基催化剂：制备及水相催化糠醛加氢脱氧反应性能

以SiO₂-Al₂O₃、γ-Al₂O₃为载体采用浸渍法制备了不同负载量的镍基催化剂,以XRD、H₂-TPR、NH₃-TPD与低温N₂吸附等技术对催化剂特性进行了表征,并进行了水相催化糠醛加氢脱氧实验研究以制备以C₅为主要成分的生物汽油。重点考察了催化剂的镍负载量、载体种类及反应温度对糠醛转化率、目标产物C₅选择性的影响,并对催化剂的重复利用性能和糠醛水相加氢脱氧反应机理进行了探讨。结果表明,Ni/SiO₂-Al₂O₃催化性能明显优于Ni/γ-Al₂O₃。在140 ℃、氢冷压3.0 MPa的优化反应条件下,14wt% Ni/SiO₂-Al₂O₃催化糠醛反应的转化率为63%,C₅选择性高达93%。升高反应温度可以提高糠醛的转化率,但反应产物的选择性降低。催化剂在第3次重复使用时糠醛的转化率明显降低,催化剂表面有明显的残留有机聚合物和积碳,达到25wt%左右。     

光动力化合物5-氨基乙酰丙酸的简便全合成

从γ-丁内酯出发, 首先发生醇解、氧化反应, 继而采用无溶剂法与硝基甲烷在KF/Al₂O₃催化下发生Henry反应, 再经湿Al₂O₃负载的CrO₃氧化得到5-硝基-4-羰基戊酸乙酯, 最后在Pd/C催化下还原得到5-氨基乙酰丙酸. 各步所合成化合物的结构经¹H NMR, IR, MS分析确证.     

全氟烷基磺酰亚胺盐催化芳香化合物硝化反应的研究

利用系列全氟烷基磺酰亚胺盐[M(NPf₂)_n]作为一种新型的Lewis酸催化剂，用于催化芳香化合物与等摩尔65% (m∶m)硝酸的硝化反应. 通过考察不同的催化剂、反应时间、反应温度和反应介质效应等因素对甲苯硝化的影响，以及比较1 mol% Yb[N(C₄F₉SO₂)₂]₃催化不同结构的取代芳烃硝化反应的效果，表明全氟烷基磺酰亚胺盐不仅具有环境友好和原子经济的特点，而且是一类比常规Lewis酸更有效的、芳香化合物硝化反应的催化剂.     

Cr-β沸石的合成与催化性能研究

在SiO₂-Cr₂O₃-(TEA)₂O-Na₂O-H₂O体系中，以四乙基氢氧化铵(TEAOH)为模板剂合成了Cr-β沸石，用XRD、IR、SEM及DTA-TGA等方法对样品进行了表征，探讨了反应混合物组成对Cr-β沸石晶化的影响，初步考查了Cr-β沸石催化苯酚与过氧化氢的羟基化反应活性。     

Lacunary Keggin Polyoxotungstate as Reaction-controlled Phase-transfer Catalyst for Catalytic Epoxidation of Olefins

A new reaction-controlled phase-transfer catalyst system, lacunary Keggin polyoxotungstate [C7H7N(CH3)3]9PW9O34 has been synthesized and used for catalytic epoxidation of olefins with H2O2 as the oxidant. Infrared spectra were used to analyze the behavior of the phase transfer of catalyst. In this system, the catalyst not only can act as homogeneous catalyst but also as heterogeneous catalyst to be easily filtered and reused. The epoxidarion reaction is clean and exhibits high conversion and selectivity as well as excellent catalyst stability.     

用于苯选择加氢制环己烯的非晶态合金Ru-La-B/ZrO2催化剂的失活与再生

 研究了在中试装置上经长期运转后的非晶态合金Ru-La-B/ZrO2催化剂的失活原因与再生方法. 结果表明: 催化剂失活不是由微孔堵塞、比表面积减小、晶粒长大或催化剂中毒而引起的,而是由于在长期运转过程中催化剂吸附了反应浆液中的Zn2+ 和反应器壁引入的Fe2+ , 通过酸洗的方法可以使催化剂的活性和选择性基本恢复.     

Highly active copper-based catalyst for atom transfer radical polymerization

Atom transfer radical polymerization (ATRP) generally requires a catalyst/initiator molar ratio of 0.1 to 1 and catalyst/monomer molar ratio of 0.001 to 0.01 (i.e., catalyst concentration: 1000-10,000 ppm versus monomer). Herein, we report a new copper-based complex CuBr/N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) as a versatile and highly active catalyst for acrylic, methacrylic, and styrenic monomers. The catalyst mediated ATRP at a catalyst/initiator molar ratio of 0.005 and produced polymers with well-controlled molecular weights and low polydispersities. ATRP occurred even at a catalyst/initiator molar ratio as low as 0.001 with copper concentration in the produced polymers as low as 6-8 ppm (catalyst/monomer molar ratio = 10(-5)). The catalyst structures were studied by X-ray diffraction and NMR spectroscopy. The activator CuIBr/TPEN existed in solution as binuclear and mononuclear complexes in equilibrium but as a binuclear complex in its single crystals. The deactivator CuIIBr2/TPEN complex was mononuclear. High stability and appropriate KATRP (ATRP equilibrium constant) were found crucial for the catalyst working under high dilution or in coordinating solvents/monomers. This provides guidance for further design of highly active ATRP catalysts.     

制备高碳醇用Cu-Zn-Zr催化剂的研究

研究了制备高碳醇用新的催化体系ＣｕＺｎＺｒ．ＣｕＺｎＺｒ催化剂可用Ｃｕ（ＮＯ３）２,Ｚｎ（ＮＯ３）２,ＺｒＯＣｌ２和Ｎａ２ＣＯ３为原料,采用并流共沉淀法制备．研究结果表明,ＣｕＺｎＺｒ催化剂对脂肪酸甲酯加氢制备高碳脂肪醇具有很高的活性．催化剂的活性测定结果及ＸＲＤ和ＴＰＲ表征结果表明,Ｃｕ和Ｚｎ都是该催化剂的活性组分,Ｃｕ０和ＺｎＯ是其活性物相,Ｚｒ组分以ＺｒＯ物相存在,对活性组分起着间隔分散作用．用ＡＳＡＰ２０００型物理吸附仪测定了催化剂的比表面积、比孔容、孔结构和孔径分布,揭示了在不同条件下制备的ＣｕＺｎＺｒ催化剂活性差异的原因     

氮掺杂碳纳米管包覆碳化硅作为不含金属的催化剂(英文)

A hierarchical metal-free catalyst consisting of nitrogen-doped carbon nanotubes decorated onto a silicon carbide (N-CNTs/SiC) macroscopic host structure was prepared. The influence of N-CNTs incorporation on the physical properties of the support was evaluated using different characterization techniques. The catalyst was tested as a metal-free catalyst in the selective oxidation of H2S and steam-free dehydrogenation of ethylbenzene. The N-CNTs/SiC catalyst exhibited extremely good desulfurization performance compared to a Fe2O3/SiC catalyst under less conducive reaction conditions such as low temperature, high space velocity, and a low O2-to-H2S molar ratio. For the dehy-drogenation of ethylbenzene, a higher dehydrogenation activity was obtained with the N-CNTs/SiC catalyst compared to a commercial K-Fe/Al2O3 catalyst. The N-CNTs/SiC catalyst also displayed good stability as a function of time on stream for both reactions, which was attributed to the strong anchoring of the nitrogen dopant in the carbon matrix. The extrudate shape of the SiC support allowed the direct macroscopic shaping of the catalyst for use in a conventional fixed-bed reactor without the problems of catalyst handling, transportation, and pressure drop across the catalyst bed that are encountered with nanoscopic carbon-based catalysts.     

氯对钌基氨合成催化剂的影响

氯离子的脱除是制备高性能钌催化剂的一个重要步骤。本文综述了新型钌基氨合成催化剂制备过程中的脱氯环节。介绍了以RuCl₃·3H₂O作为活性前驱体的钌催化剂中氯离子的来源、氯在催化剂中的存在方式、它对催化剂的毒害作用以及去除氯离子的方法。     

Chemical Immobilization of Heteropolyacid Catalyst on Inorganic Mesoporous Material for use as an Oxidation Catalyst

Recent progress on the chemical immobilization of heteropolyacid (HPA) catalyst on inorganic mesoporous material is reported in this review. Mesostructured cellular foam silica, mesoporous carbon, and nitrogen-containing mesoporous carbon were used as supporting materials. The mesoporous materials were modified to have a positive charge, and thus, to provide sites for the immobilization of HPA catalyst. By taking advantage of the overall negative charge of heteropolyanion, the HPA catalyst was chemically immobilized on the surface-modified mesoporous material as a charge-compensating component. Characterization results showed that the HPA catalyst was finely and molecularly dispersed on the surface of mesoporous material via strong chemical immobilization, and that the pore structure of mesoporous material was still maintained even after the immobilization of HPA catalyst. The supported HPA catalysts were applied to the model vapor-phase ethanol conversion, 2-propanol conversion, and methacrolein oxidation reactions. The supported HPA catalyst showed a better oxidation catalytic activity than the unsupported HPA catalyst in the model reactions. The enhanced oxidation catalytic performance of the supported HPA catalyst was attributed to the finely dispersed HPA catalyst, which was chemically immobilized on the positive site of mesoporous material by sacrificing its proton (Brönsted acid site). The HPA catalyst chemically immobilized on mesoporous material served as an excellent oxidation catalyst.     

Dehalogenation of Aryl Halides Catalyzed by Montmorillonite Immobilized Bimetal Catalyst in Aqueous System

A novel bisupported bimetal catalyst PVP-PdCl2-FeSO4/Al-Mont-PEG600 was prepared by immobilization of PVP (poly (N-vinyl-2-pyrrolidone)) supported bimetallic catalyst using alumina pillared inartificial montmorillonite as the carrier. This catalyst has good dehalogenation activity and selectivity to aryl halides-o-chlorotoluene in aqueous system in the presence of phase transfer catalyst (PEG) and sodium formate as hydrogen source. The catalyst also shows good reusability.     

Hydrophobic polymer-supported scandium catalyst for carbon-carbon bond-forming reactions in water

It has been revealed that a hydrophobic polymer-supported scandium(III) catalyst prepared from sulfonated polystyrene resin is an effective catalyst for carbon-carbon bond-forming reactions such as Mukaiyama aldol reactions in water. According to studies on loading levels of scandium, hydrophobicity of the catalyst is a key for the efficient catalysis. The scandium catalyst was successfully recovered and reused. Several ketones instead of aldehydes were also used as substrates in the aldol reactions. Some 1,4-addition reactions also occurred using the scandium catalyst in water.     

Rapid microwave promoted heterocyclization of primary amines with triethyl orthoformate and sodium azide using zinc sulfide nanoparticles as recyclable catalyst

Microwave assisted synthesis of 1-substituted-1H-tetrazoles was developed using zinc sulfide nanoparticles as heterogeneous catalyst under solvent free conditions. The tetrazole derivatives were easily prepared through hterocyclization of primary amines with triethyl orthoformate and sodium azide in the presence of ZnS NPs. The experimental results were shown that a series of 1-substituted tetrazoles were synthesized under microwave irradiation by ZnS NPs as an effective and reusable heterogeneous catalyst in excellent yields. This protocol has advantages rather than other reported methods such as non-acidic catalyst, solvent free conditions and greener process as well as a solid recyclable catalyst. The catalyst was recovered and reused for several cycles with consistent activity.