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Steinfeldt N.,Leibniz Institute for Catalysis at the University of Rostock
Langmuir | Year: 2012

The temporal evolution of Pt nanoparticle formation in ethylene glycol solution from H2PtCl6·6H2O at 90 °C for different molar ratios of NaOH to Pt (84, 6.5, and 2) in the presence or absence of poly(N-vinyl-2-pyrrolidone) (PVP) as protecting agent was followed in situ by small-angle X-ray scattering (SAXS). The SAXS profiles were analyzed regarding particle size and size distribution using the Guinier approximation and the indirect Fourier transform technique (IFT). The NaOH to Pt ratio has an influence on the integral nanoparticle formation rate as well as on the metal reduction rate and the ratio of nucleation to growth reactions. The fastest nanoparticle formation rate was observed for the NaOH/Pt ratio of 6.5. The obtained results indicate that the differences in the particle formation rate might be due to differences in the reduction rate of the formed Pt complexes. In alkaline reaction media (NaOH/Pt = 84 or 6.5), small nanoparticles with a relatively narrow size distribution were formed. Therefore, it is assumed that for these NaOH/Pt ratios the particle formation is dominated by nucleation reactions. Additionally, the in situ studies point out that nanoparticles prepared at the NaOH/Pt ratio of 84 do not grow further after attaining a certain particle size. For a NaOH to Pt ratio of 2, that means in acidic medium, particle formation should be dominated by growing processes and, therefore, larger particles are formed accompanied by a broader particle size distribution. The influence of PVP on the nanoparticle formation rate is relatively low. However, in acidic medium, the presence of PVP is necessary in order to protect the formed nanoparticles from irreversible aggregation reactions. © 2012 American Chemical Society.


Wu X.-F.,Leibniz Institute for Catalysis at the University of Rostock | Neumann H.,Leibniz Institute for Catalysis at the University of Rostock | Beller M.,Leibniz Institute for Catalysis at the University of Rostock
Chemical Society Reviews | Year: 2011

Palladium-catalyzed carbonylative coupling reactions of aromatic halides and related compounds have undergone a rapid development during recent years. Nowadays, a plethora of palladium catalysts are available for the synthesis of ketones, alkynones, chalcones, etc., which are important intermediates in the manufacture of dyes, pharmaceuticals, agrochemicals, and other industrial products. In this critical review, we summarize the development of these carbonylative transformations with carbon nucleophiles (136 references). © 2011 The Royal Society of Chemistry.


Weding N.,Leibniz Institute for Catalysis at the University of Rostock | Hapke M.,Leibniz Institute for Catalysis at the University of Rostock
Chemical Society Reviews | Year: 2011

The [2+2+2] cycloaddition reaction has become an invaluable tool for the synthetic chemistry in recent years, due to the increase of complexity of the accessed target molecules by this methodology. Over several decades, the members of group 9 of the periodic table have contributed significantly to the development and understanding of this particular cycloaddition reaction. On the other hand, catalyst complexes containing alkenes as ligands are widely used today as either catalysts or as precursor molecules for the facile generation of catalytically active metal species. In this tutorial review we want to describe the catalytically relevant chemistry of group 9 metal-alkene complexes and compile some recent applications in [2+2+2] cycloaddition reactions. © 2011 The Royal Society of Chemistry.


Wu X.-F.,Zhejiang Sci-Tech University | Wu X.-F.,Leibniz Institute for Catalysis at the University of Rostock | Neumann H.,Leibniz Institute for Catalysis at the University of Rostock | Beller M.,Leibniz Institute for Catalysis at the University of Rostock
Chemical Reviews | Year: 2013

The major developments of palladium-catalyzed carbonylative syntheses of heterocycles was reviewed. The application of palladium catalyzed carbonylation reactions in the synthesis of four membered lactones was first reported by Cowell and Stille in 1980. They used PdCl2(PPh3) 2 as catalyst, and the lactones were synthesized in high yields under mild conditions. Dupont and co-workers developed a Pd(OAc)2/2- PyPPh2 system for the production of various lactones from alkynols. Palladium catalyzed carbonylation of aziridines represents another convincing procedure for the synthesis of lactams. The methodologies developed by Brickner and Tsuji and their co-workers successfully avoid the use of aziridines in the preparation of lactams, but the specificity of starting materials limited the scope. Six-membered ring lactones were produced preferentially in acetonitrile using cationic palladium complexes coordinated by certain chelating diphosphines (dppb) as catalyst.


Bentrup U.,Leibniz Institute for Catalysis at the University of Rostock
Chemical Society Reviews | Year: 2010

Several in situ techniques are known which allow investigations of catalysts and catalytic reactions under real reaction conditions using different spectroscopic and X-ray methods. In recent years, specific set-ups have been established which combine two or more in situ methods in order to get a more detailed understanding of catalytic systems. This tutorial review will give a summary of currently available set-ups equipped with multiple techniques for in situ catalyst characterization, catalyst preparation, and reaction monitoring. Besides experimental and technical aspects of method coupling including X-ray techniques, spectroscopic methods (Raman, UV-vis, FTIR), and magnetic resonance spectroscopies (NMR, EPR), essential results will be presented to demonstrate the added value of multitechnique in situ approaches. A special section is focussed on selected examples of use which show new developments and application fields. © 2010 The Royal Society of Chemistry.


Bruckner A.,Leibniz Institute for Catalysis at the University of Rostock
Chemical Society Reviews | Year: 2010

Electron Paramagnetic Resonance (EPR) offers widespread opportunities for monitoring catalytically relevant species that contain unpaired electrons under conditions close to those of heterogeneous catalytic gas and liquid phase reactions. In this tutorial review, after introducing basic theoretical and experimental principles of the technique, selected examples of typical applications are discussed that comprise (1) transition metal ions in paramagnetic valence states such as vanadium, (2) radical anions such as O - formed on oxide surfaces and (3) electrons in ferromagnetic particles such as nickel as well as in conduction bands of organic conductors such as polyaniline. © 2010 The Royal Society of Chemistry.


The major objective of this proposal is the development of new active and selective catalysts based on earth abundant metals (e.g. Fe, Mn, Co, Cu). These catalysts will be used for improved synthetic transformations which are of interest for organic chemistry in general and which are also of significant practical value for the chemical and life science industries. Traditional catalysts based on non-noble metals are not efficient for hydrogenation and dehydrogenation processes under mild conditions. However, by creating a suitable microenvironment with M-N interactions they are becoming active and selective. According to our concept the suitable surrounding will be created either by using nitrogen-containing pincer ligands or nitrogen-doped graphenes. Consequently, a variety of both molecular-defined homogeneous catalysts as well as nano-structured heterogeneous materials will be prepared, characterized and tested in various catalytic applications. More specifically, the following redox transformations will be investigated: Hydrogenation and transfer hydrogenation of carboxylic acids, esters, and nitriles; hydrogenation of amides and peptides; hydrogenation of carbon dioxide and selective oxidative coupling of alcohols to esters, amides, and nitriles. Furthermore, waste-free carbon-carbon bond forming reactions such as alkylations with alcohols and domino-synthesis of heterocycles from alcohols will be exploited. Finally, homogeneous and heterogeneous catalysts from earth abundant metals will be used in industrially relevant oxidative carbonylation reactions. With respect to methodology this proposal combines homogeneous with heterogeneous catalysis, which will result in new ideas for both fields.


Grant
Agency: Cordis | Branch: H2020 | Program: MSCA-ITN-ETN | Phase: MSCA-ITN-2015-ETN | Award Amount: 3.32M | Year: 2016

Transition metal catalysts are formidable tools towards greener chemistry, allowing for low-waste, energy-efficient, and selective reactions. However, the noble metals (Ru, Os, Rh, Ir, Pd, Pt) that are currently most common in homogeneous catalysts suffer from high toxicity and environmental impact in addition to their scarcity and ensuing high cost. First-row metals (Mn, Fe, Co, Ni, Cu) are emerging as environmentally benign alternatives, but to this day rarely equal the performance of their noble counterparts. The NoNoMeCat network aims at providing excellent and structured interdisciplinary training to a generation of young researchers in the field of Non-Noble Metal homogeneous Catalysis who will push the boundaries of the field in terms of catalyst stability, selectivity, mechanistic understanding, and scalability. These challenges are addressed in three areas of high fundamental and practical significance: the oxidation of hydrocarbons, the formation of new C-X bonds (C-C, C-N) bonds through cross-coupling reactions, and clean energy production. NoNoMeCat will enrol 14 Early Stage Researchers (ESRs) who will receive structured training in experimental and theoretical aspects of non-noble metal chemistry as well as transferable skills such as research integrity, scientific communication and public outreach. Tight integration of non-academic partners will expose all ESRs to aspects of both fundamental interdisciplinary research and industrial application, paving the way for long-standing intersectorial collaborations.


Grant
Agency: Cordis | Branch: H2020 | Program: MSCA-ITN-EID | Phase: MSCA-ITN-2015-EID | Award Amount: 1.28M | Year: 2015

The HUGS concept ( HUmins as Green and Sustainable precursors of eco-friendly materials and biofuels) discloses an integrated multidisciplinary EID proposal with involvement of high-tech SMEs two research centers and 3 world class universities in the area of biorefinery. All partners have been chosen by their complementary expertise and their extensive experience in supervising PhD programs and coordinating international scientific projects. The proposed methodology and approach focuses on side-stream valorization of FDCA/PEF polyester production process developed by Avantium. HUGS aims to provide breakthrough knowledge combined with an excelling training program on humin by-products by implementing work packages which will respectively focus on side streams to building blocks; building blocks to composites; safety and toxicity aspects; training and dissemination activities and management, communication and public engagement. 5 PhD are envisaged to be recruited to reach these ambitious goals with regards to multidisciplinary training and beyond stateof-the-art research. Each PhD will be seconded at the company as well as between the collaborating universities aiming to develop a number of essential leadership, entrepreneurial, communication and scientific skills in program fellows. All partners will organize week-long dedicated training courses in their field of expertise (homo- & heterogeneous catalysis, physico-chemical polymer analyses, toxicity and safety, IPR, techno-economic evaluation) over the total duration of the project. The proposed research is novel and highly original which will justify scientific publications in top-ranked journals together with a unique training program. PEF is unique in being the first technical superior and 100% biobased plastic to come to the market. The HUGS project as being closely linked to PEF commercialization which it will guarantee maximal exploitation of the results, communication and public engagement.


Grant
Agency: Cordis | Branch: H2020 | Program: BBI-IA-DEMO | Phase: BBI.VC1.D1-2015 | Award Amount: 10.61M | Year: 2016

The GreenSolRes-Project demonstrates the levulinic acid value chain of lignocellulosic feedstocks to high-value products in a 3-step approach on TRL 6 to 7: First, the feedstock of GFBs existing demo plant in Caserta is shifted to lignocellulosic residues or wastes by implementation of a char separation unit and a boiler to cover the process energy demand. A new product separation unit enables more efficient and purer levulinic acid production, leading to a capacity of 10kta at the end of the project. In a 2nd step the versatile platform chemical levulinic acid is hydrogenated to 2-methyltetrathydrofuran (MTHF), gamma-valerolactone (GVL) and 1,4-pentanediol (PDO) in a highly efficient direct process developed by RWTH Aachen. These can be produced in the same reactor with a single catalyst by tuning the process conditions, the demo-plant is constructed by GFB. Third, the application of the products as solvents is validated in adhesives and the pharma sector as substitute of their more ecotoxic C4-analogues. Additionally, Henkel studies the development of respective new polymers with improved properties. The basic engineering of first commercial plants for these steps supports rapid upscaling and exploitation after the project. This will release these products from the niche markets they are confined to due to ineffective existing production routes. At about 1 EUR/kg levulinic acid and competative prices compared to their their C4-counterparts these chemicals and related products will boost the bio-based market as they have a high GHG avoidance of at least 70% and an additional value to society via better health&safety properties. The whole value chain from e.g. forestry residues to consumer products is assessed for environmental sustainability, risks and health&safety to support business case development and market implementation.

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