A Highly Efficient Catalyst Au/MCM-41 for Selective Oxidation Cyclohexane Using Oxygen

The liquid-phase highly efficient selective oxidation cyclohexane to cyclohexanol and cyclohexanone over Au/MCM-41 catalyst was carried out in a solvent-free system, which oxygen as the only oxidant and the reaction conditions are very moderate. The Au/MCM-41 was characterized by XRD, N₂adsorption/desorption, UV-Vis, XPS, and ICP-AES.     

Gold-Nanoparticle Decorated Monosized Magnetic Polymer Based Catalyst: Reduction of 4-Nitrophenol

The objective of this study was to fabricate a multifunctional catalyst for removal of environmental pollutants. By this aim, poly(mono-2-(methacryloyloxy)ethyl succinate-co-glycerol dimethacrylate) “poly(MMES-co-GDMA)” monosized microbeads with carboxyl functionality were synthesized 5 µm in diameter. Iron oxide nanoparticles were attached onto the polymeric microbeads to obtain superparamagnetic properties for easily collecting them from the reaction medium by using natural magnet. The magnetic polymer microbeads were decorated with gold nanoparticles ca. 15 nm in size. The magnetic-monodisperse catalyst carrying gold nanoparticles exhibited several advantages with respect to similar plasmonic catalysts in the form of nanoparticles, like higher aggregation resistance, easier recovery from the reaction medium with natural magnets and reuse of catalyst without leaching gold nanoparticles. The magnetic gold catalyst was characterized by scanning electron microscopy (SEM), vibrating sample magnetometry (VSM) and X-ray diffraction spectrophotometry (XRD). This newly designed catalyst was used to degrade a toxic organic substance, 4-nitrophenol (4-NP) in an aqueous medium. The degradation process of 4-NP to 4-aminophenol (4-AP) was monitored by a UV–Visible spectrophotometer. The effects of reaction conditions, catalyst and organic pollutant concentrations and temperature, on the plasmonic catalytic activity were determined. The results of repetitive trials were successful with high catalytic activity for the reduction of 4-NP to 4-AP form in several minutes by using and reusing the synthesized catalyst.     

Crosslinked PVA/PVP Supported Silver Nanoparticles: A Reusable and Efficient Heterogeneous Catalyst for the 4-Nitrophenol Degradation

Well-organized and stable silver nanoparticles (AgNPs) were successfully prepared within polymeric film of polyvinyl alcohol and Polyvinylpyrrolidone as supporting matrix. The free-standing film was obtained by using the casting technique. Electron microscopy techniques confirmed the formation of spherical AgNPs of 15 nm size. The prepared AgNPs were crystallized in face-centered cubic structure as indicated by X-ray diffraction. The as-prepared nanocomposite film exhibited good catalytic properties in the complete catalytic degradation of 4-nitrophenol using sodium borohydride as a reducing agent. The AgNPs are tightly held within a polymeric matrix which facilitates their recovery and reuse for several cycles.     

Pd/MIL-101在温和条件下高选择性催化苯乙酮加氢

利用简单浸渍法制备出一系列Pd/MIL-101催化剂,并通过粉末XRD等表征催化剂。在40℃、0.1 MPa H2、无碱的条件下,利用Pd/MIL-101多相催化苯乙酮加氢生成α-苯乙醇,研究发现,负载量为2.04wt%的Pd/MIL-101催化剂在相同的反应条件下,可以在更短的时间内将苯乙酮完全转化,且选择性在96%,进一步通过时间和转化率曲线也能证明,在各个时间段,2.04wt%的催化剂催化苯乙酮加氢反应的速率是最快的,也就是催化活性最高。     

An Efficient and Recyclable Fluorous Palladium Catalyst for the Room-Temperature Suzuki Reaction

Abstract  

A new fluorous nano-palladium catalyst was prepared and characterized. The catalytic activity of the catalyst has been evaluated for the Suzuki reaction of aryl halides and aryl boronic acids to afford the corresponding products in high yields. The reaction proceeded smoothly in the presence of 0.1 mol% catalyst in EtOH/H₂O at room temperature. In addition, the catalyst could be recovered by fluorous liquid–liquid separation and reused for three times without significant loss of activity.     

Strontium Doped MCM-41: A Highly Efficient,Recyclable and Heterogeneous Catalyst for the Synthesis of Phenoxy Pyrazolyl Pyrazolines

Strontium doped MCM-41 (Sr-MCM-41) has been synthesized as an efficient, heterogeneous and recyclable catalyst. The catalyst, Sr-MCM-41 is characterized by various techniques such as FTIR, SEM, EDX, elemental Mapping, TEM, TGA, BET, XRD, XPS and ICP-AES analyses. The catalytic activity of the catalyst (Sr-MCM-41) has been explored by synthesizing a library of phenoxy pyrazolyl pyrazoline derivatives in excellent yield (96–98%) under microwave irradiation (3–5 min) using ethanol as solvent. The catalyst could be recycled upto five cycles.

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石墨烯负载的钴纳米粒子催化还原4-硝基苯酚

以葡萄糖为碳源、NH4Cl为发泡剂、纳米金属Co为促进葡萄糖石墨化的催化剂,通过一步法制备了Co-石墨烯复合材料,实现了石墨烯的形成和Co纳米粒子原位生长的同步进行。通过XRD、FTIR、XPS、Raman、UV-Vis和TEM对该复合材料的结构与形貌进行了表征。将Co-石墨烯复合材料用于催化还原对硝基苯酚(4-NP)反应。在室温下,使用4 mg催化剂可于8 min内将1.39 mg 4-NP全部还原。复合材料通过简单的磁分离可循环利用,使用5次后,4-NP转化率依然高达86%。     

Amino-functionalized Ionic Liquid as an Efficient and Recyclable Catalyst for Knoevenagel Reactions in Water

The Knoevenagel condensation of aromatic aldehydes with malononitrile and ethyl cyanoacetate using amino-functionalized ionic liquid, 1-aminoethyl-3-methylimidazolium hexafluorophosphate as catalyst was successfully performed in aqueous media. The catalyst can be recycled and reused at least six times without apparently loss of activity.      

芳樟叶浸出液还原制备对硝基苯酚加氢银催化剂

采用芳樟叶浸出液,通过原位还原和等体积浸渍的方法制备负载型纳米银催化剂,并以对硝基苯酚(4-NP)加氢反应为模型反应,考察催化剂载体,焙烧条件等对负载型纳米银催化剂性能的影响,并采用扫描电镜(SEM),热重分析(TG)和红外光谱( FT-IR)等表征手段对催化剂进行表征.结果表明,以TiO2为载体制备的纳米银催化剂具有...     

In Situ Anchoring Ultra Small Au Nanoparticles by Conformal Coating of Carbon Layer within the Micro-Environments of Mesoporous Silica for Highly Efficient Catalytic Reduction of 4-nitrophenol

Catalysis Letters - For the noble-metal based catalysts, the metal dispersion and sinter resistance of the metal nanoparticles (NPs) are the most vital factors for their application in series...     

Recyclable Magnetic Camphor Sulfonic Acid: A Reliable and Highly Efficient Ionic Organocatalyst for Benzothiazin-4-One Synthesis in Green Media

Catalysis Letters - Organocatalysts, like a minimalistic biocatalyst, pursue to reduce metal consumption with low cost, and low toxicity targeting to become a green strategy in organic...