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.     

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.     

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。     

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.     

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.     

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.     

SiO2骨架支撑MoOx催化剂用于正庚烷异构化反应

 采用SEM，XRD，EDS及N2吸附－脱附方法研究了骨架型MoOx－SiO2催化剂和负载型MoOx／SiO2催化剂的物理化学结构，并在常压固定床流动反应器上考察了两种催化剂对正庚烷异构化反应的催化性能．结果表明，在MoOx－SiO2催化剂中，44．6％的SiO2即可起到很好的骨架支撑作用；MoOx晶相以足够大的空间区域聚集包裹在SiO2骨架中，形成类似MoOx催化剂的独特的中孔结构．与MoOx催化剂相比，MoOx－SiO2催化剂显著提高了机械强度，并维持了MoOx催化剂较高的活性和选择性．由于钼物种和载体之间的相互作用，负载型MoOx／SiO2催化剂表现出较低的比活性．脉冲注入H2S实验结果表明，MoOx－SiO2催化剂具有较好的抗硫性能．     

Low Concentration Limitations of Catalyst and Conventional Free Radical Polymerization in ICAR ATRP of Butyl Methacrylate With PMDETA as the Ligand

Low concentration limitations of the catalyst and conventional free radical polymerization are investigated in the system of initiators for continuous activator regeneration atom transfer radical polymerization (ICAR ATRP) of butyl methacrylate (BMA), in which 2,2-azobisisobutyronitrile (AIBN) is used as a reducing agent, pentamethyldiethylenetriamine (PMDETA) as a ligand, copper bromide (CuBr₂) as a catalyst and ethyl 2-bromoisobutyrate (EBiB) as an initiator. Results show that conventional radical polymerization happens in the early stage of the ICAR ATRP of BMA when the amounts of AIBN are 3～25 times of the catalyst. And with the increase of the conversion, the BMA polymerization solely conducts the controlled radical polymerization (CRP). The low concentration limitations (based on monomer) of the catalyst required in ICAR ATRP of BMA with good controllability are found to be closely related to the molar ratio of initiator to catalyst, which is determined by the stability of the catalyst/ligand complex. The smaller molar ratio of initiator to catalyst allows lower concentration limitations of the catalyst.     

镍基催化剂上甲烷干气重整反应的优化(英文)

利用单一因子法、正交设计法以及均匀设计法深入考察了镍基催化剂上的甲烷二氧化碳重整反应的影响因子、催化剂组成、最佳反应条件以及助剂效应。研究发现,最佳催化剂组成为：Ｎｉ,８５ｗｔ％：ＭｇＯ,３ｗｔ％;ＣｅＯ２,３ｗｔ％;载体：Ａｌ２Ｏ３。助剂可有效抑制催化剂积碳,但同时由于覆盖部分金属活性位,一定程度上降低了催化剂的活性。该催化剂上５００ｈ甲烷二氧化碳重整反应稳定性试验表明该催化剂性能优越．有较高的开发潜力。     

合成低碳醇用超细Mo-Co-K催化剂的XPS研究

 采用XPS技术对氧化态及还原态超细Mo－Co－K催化剂进行了研究．结果表明,在氧化态超细Mo－Co－K催化剂中,钼和钴分别以Mo6＋和Co2＋物种存在,催化剂中各物种之间存在着相互作用;随着Co／Mo比的增大,还原态催化剂中Mo4＋物种的含量逐渐增大并出现极大值;催化剂上合成低碳醇反应性能与其表面的Mo4＋物种有关．将催化剂表面的Mo4＋物种含量与其合成低碳醇选择性进行关联,发现二者存在着很好的对应关系．此外,对超细Mo－Co－K催化剂上合成低碳醇反应的活性中心进行了初步探讨．     

苯酚在Ln-ZrO_2催化剂上直接氧化制取邻苯二酚的研究

以ＬｎＺｒＯ２作为苯酚选择氧化催化剂，用过氧化氢氧化，得到邻苯二酚选择性高达８５７％的良好结果，添加稀土元素镧、钕的氧化锆催化剂与单纯的二氧化钛催化剂相比，邻苯二酚选择性分别提高了７３５％和６７８％。     

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.     

Dry Reforming of Methane Over Cobalt Catalysts: A Literature Review of Catalyst Development

Dry reforming of methane produces syngas with desirable H₂/CO ratio. Besides noble metal catalysts, the cobalt catalyst performs good activity in this reaction. However, carbon deposition and catalyst deactivation are becoming the main problems inhibiting the scale up of this process into industrial application. Recently, many scientists were trying to increase the activity as well as the stability toward coking by using variants of support, promoter, and combination of metal series catalyst. This paper presents a recent technology of methane dry reforming over cobalt metal-base catalyst, covering the catalyst activity and their resistance of catalyst deactivation.     

木质素负载钯催化剂的制备及对Heck反应的催化性能

以天然木质素和PdC l2为原料,合成了木质素负载钯催化剂,用IR、XPS、TG、DTA等对其进行了表征.研究表明,该催化剂在空气氛围中能催化丙烯酸与芳基碘的Heck反应,并有一定的重复使用性能.     

Polymerization of Vinyl Monomers Using Oxidase Catalysts

Polymerization of vinyl monomers using oxidase as catalyst has been performed under argon in the presence of acetylacetone as a mediator and without the use of hydrogen peroxide. The polymerization of acrylamide was catalyzed by a laccase or sarcosine oxidase catalyst in distilled water and efficiently produced the polymer with high molecular weight. In the polymerization using the laccase catalyst, the effects of temperature, time, and amounts of enzyme and mediator have been systematically investigated. On the other hand, various other oxidases such as bilirubin, choline, and xanthine oxidases showed no or little activity for the vinyl polymerization. The laccase/acetylacetone catalyst induced the polymerization of methyl methacrylate and styrene in a mixture of water and tetrahydrofuran. Laccase alone also acted as a catalyst for the vinyl polymerization of acrylamide and methyl methacrylate without acetylacetone. In the polymerization of methyl methacrylate using lipoxidase as the catalyst in the presence of acetylacetone, the reaction occurred in air.     

高性能燃料电池催化剂及其5kW常温常压免增湿电堆

应用高压有机溶胶法制得高性能的Pt/C催化剂.该催化剂的活性颗粒度达2.8 nm,活性比表面为450 m2/g,并进行了小批量试产(10 g).建立新型直接涂膜电极和免增湿技术,并制作了275 cm2的膜电极,设计和组装5 kW质子交换膜燃料电池电堆,以氢气为燃料,空气为氧化剂在常温常压免增湿条件下试运行,电堆连续运行10 h,输出功率基本稳定不变.     

Copper‐ and phosphine‐free Sonogashira coupling reaction catalyzed by silica–(acac)‐supported palladium nanoparticles in water

A palladium‐based catalyst supported on acac‐functionalized silica was used as a heterogeneous catalyst for the Sonogashira cross‐coupling reaction of various aryl halides and phenylacetylene under copper‐ and phosphine‐free conditions. This catalytic system serves as an efficient and stable catalyst for this cross‐coupling reaction and allows easy separation and recycling of the catalyst. The catalyst could be recycled for five runs without appreciable loss of its catalytic activity. In addition, the reaction was carried out in water as a green solvent. Copyright © 2014 John Wiley & Sons, Ltd.