Download or read book Oligomerization and Polymerization of Ethylene by Phenoxy imine Titanium Catalysts written by Astrid Cordier and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 1-hexene is one of the most important olefin used as comonomer for the production of value-added polyethylenes (HDPE, LLDPE). In the field of selective ethylene trimerization employing titanium-based catalysts, specific single tridentate phenoxy-imine complexes (SFI) display the highest activity and 1-hexene selectivity upon activation with methylaluminoxane (MAO). However, ethylene polymerization is an unavoidable side reaction affecting both 1-hexene selectivity and process operations. Although being a major drawback, the causes of polymerization remain a grey area since few studies were dedicated to its deciphering. To handle this challenge , an original “polymer-to-catalyst” strategy was implemented. An extensive temperature study (26-80°C) revealed that the highest 1-hexene activity is reached between 30 °C and 40 °C while polymer production is prominent above 50 °C. Polyethylenes obtained were analyzed by SEC, NMR DSC, and advanced segregation techniques (CEF, SIST, rheology). Molar masses above 10^5 g mol-1 were identified along with a 1-hexene content below 1 mol %. An increase of dispersity (Ɖ > 2) with temperature was ascribed to an evolution from single to multi-site polymerization catalysis. Kinetic studies proved that polymer is continuously produced even at short reaction time, for any reaction temperature. Other parameters (addition of 1-hexene, hydrogen and use of trimethylaluminum) were found to impair the trimerization selectivity and/or activity of the system. Nevertheless, it was possible to lower the selectivity in polyethylene by premixing the complex with MAO. After analyzing the possible routes for the polymerization catalyst formation, the hypotheses of temperature and MAO-induced complex alterations were considered. Regarding the latter, a molecular ligand-free Ziegler-Natta catalyst, modeled using TiCl4/MAO, and the synthesized (FI)Ti(III)Cl2 activated by MAO could not explain polymer production in the SFI system. Formation of a polymerization species upon thermal alteration of the SFI complex was evidenced. This [O-,N,O-]-type species displays common features regarding catalytic response to 1-hexene compared to the polymerization catalyst in the SFI system although it could not reach the same catalytic performances. The formation of a bis(phenoxy-imine) complex (FI)2TiCl2 was evidenced in this thesis and is a promising avenue worth exploring. Eventually, although the exact species has not yet been identified, this work enabled to guide the focus of further investigations on activation process and complex rearrangement by ligand mobility.

Download or read book Living Stereoselective Olefin Polymerizations Using Titanium Bis phenoxyimine Catalysts written by Andrew Felix Mason and published by . This book was released on 2006 with total page 644 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Olefin Upgrading Catalysis by Nitrogen based Metal Complexes II written by Giuliano GIAMBASTIANI and published by Springer Science & Business Media. This book was released on 2011-05-19 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: Olefin Upgrading Catalysis by Nitrogen-based Metal Complexes II: State-of-the-art and Perspectives provides a critical review of the state-of-the-art developments in industrially relevant processes connected to efficient and selective olefin upgrading. Specific attention is devoted to catalysts containing imine- and amine-based ligands. All the chapters in this book have been designed to provide a systematic account of the vast amount of information available for this type of catalyst as well as to highlight the factors that ultimately control the catalyst’s performance and productivity. A comprehensive panorama of catalyst precursors is presented, spanning from group 10 α-diimine complexes and iron and cobalt 2,6-bis(imino)pyridine derivatives, to vanadium, chromium, titanium, zirconium and lanthanide complexes supported by nitrogen-containing ligands. The authors of this collective work are currently involved in the development of imine-based catalysts for efficient and selective olefin upgrading and the majority of them have dedicated most of their scientific career to this important field. In writing this book, their major goal is to transfer as many ideas and experiences as possible to the global audience of scientists engaged in this area of research.

Download or read book Catalytic Olefin Polymerization written by T. Keii and published by Elsevier. This book was released on 1990-09-12 with total page 597 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent development of a new generation of Ziegler-Natta Catalysts using either magnesium dichloride as carrier or methylaluminoxane as cocatalyst has markedly stimulated the research activity in the field of olefin polymerization. These discoveries have not only yielded economical processes for polyolefin production but also opened the way to a new generation of novel polymers. Moreover, the nature of active species is being clarified well by the effort to simplify catalyst systems. The present volume includes 38 papers from the 31 lectures and 18 posters presented at the symposium on `Recent Developments in Olefin Polymerization Catalysts', which covered the following topics: Overview of super-active homogeneous and heterogeneous catalysts, kinetic profile of olefin polymerization including copolymerization, characterization of catalysts and polymers, methods for the determination of active center concentration, role of Lewis bases on the catalysts isospecificity, polymerization mechanisms, and synthetic pathways for functionalized polyolefins. The contents are well balanced between fundamental research and application as well as between homogeneous and heterogeneous catalyst systems.

Download or read book Organometallic Reactions and Polymerization written by Kohtaro Osakada and published by Springer. This book was released on 2014-07-15 with total page 307 pages. Available in PDF, EPUB and Kindle. Book excerpt: This compilation provides advanced graduate students and researchers with a structured overview of olefin polymerization. Divided into eight chapters written by international experts, this book covers polymerization using various organotransition-metal catalysts, including early and late transition metal complexes, new trends in olefin oligomerization and related reactions. All authors address the historic and scientific backgrounds of the field as well as current research progress and potential for further research. The complete book is designed to present eight independent lectures and, because all authors are well versed in organometallic chemistry, each is based on a profound understanding of the reactions and structures of organotransition metal complexes. This book is an ideal accompaniment for researchers taking courses in olefin polymerization and also serves as a valuable resource for teachers and lecturers of chemistry when planning and researching material for advanced lecture courses.

Download or read book Novel Titanium IV Catalysts for Olefin Polymerization written by Saman Damavandi and published by LAP Lambert Academic Publishing. This book was released on 2013 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of olefin polymerization has been remarkably renewed with the use of metallocene and post metallocene catalyst. Novel transition-metal complexes were studied as catalysts in ethylene polymerization. The aim of this work is to investigate the feasibility of replacing the cyclopentadienyl ligands of metallocenes by bis(aminotropone) ligands as well as by new bis(imino)pyridinato ligands without losing the good properties of the metallocenes, such as high activity and formation of linear polymer. It was presumed that the polymerization mechanism and the active center in ethylene polymerization would be similar for iminopyridinato and metallocene catalysts. Titanium (IV) and nickel (II) catalysts based on bis(anilinotropone) ligands were prepared and their structures determined to clarify the relationship between structure of the catalyst precursor and polymerization results. In experimentation, the syntheses, structures and olefin polymerization behavior of Ti complexes containing a pair of chelating aminotropone [O-N] ligands are reported. DFT studies revealed that bis(aminotropone) Ti complexes, when activated, provide a metal alkyl in the cis position to a vacant coordina

Download or read book Metal Catalyzed Polymerization written by Samir Chikkali and published by CRC Press. This book was released on 2017-08-03 with total page 227 pages. Available in PDF, EPUB and Kindle. Book excerpt: The proposed book focusses on metal mediated/catalyzed “controlled/living radical polymerization” (CRP/LRP) methods. It surveys a wide variety of catalyzed polymerization reactions, making it essentially a “one stop” review in the field. A significant contribution to polymer science is “metathesis polymerization” discovered by Grubbs and others. The book will cover various metathesis polymerization methods and implications in polymer industry.

Download or read book Catalytic Polymerization of Olefins written by T. Keii and published by Elsevier. This book was released on 1986-04-01 with total page 505 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers the proceedings of a symposium which was attended by researchers from all over the world who reported on and discussed recent advances in the field of catalytic polymerization of olefins. Over two decades have elapsed since the discovery of the Ziegler-Natta catalyst. Tremendous research effort has been aimed at improving this marvelous catalyst. In twenty-five years since the first publication, more than 15,000 papers and patents on the subject and on related subjects have appeared. This effort has yielded new generations of Ziegler-Natta catalysts with superior activity and stereospecificity. The complexities arising from the heterogeneity of the catalyst, however, have hindered understanding of the catalytic processes which take place on the catalyst surface. Nevertheless, many fundamental features of the catalyst system have now been clarified reasonably well. Recently a highly active homogeneous catalytic system has been developed, which is capable of catalyzing even isotactic polymerization of propene. There is no doubt that this finding will not only contribute to our understanding of the detailed mechanism of polymerization but also stimulate the development of various kinds of tailored polymers. Thus this subject will remain of paramount importance in the development of chemistry and polymer science for a long time to come.

Download or read book Oligomerization of Ethylene with Soluble Transition metal Catalysts written by Gisela Henrici-Olivé and published by . This book was released on 1974 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Polymer Molecular Weights written by Philip E. Slade and published by . This book was released on 1975 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Handbook of Transition Metal Polymerization Catalysts written by Ray Hoff and published by John Wiley & Sons. This book was released on 2018-04-20 with total page 895 pages. Available in PDF, EPUB and Kindle. Book excerpt: Including recent advances and historically important catalysts, this book overviews methods for developing and applying polymerization catalysts – dealing with polymerization catalysts that afford commercially acceptable high yields of polymer with respect to catalyst mass or productivity. • Contains the valuable data needed to reproduce syntheses or use the catalyst for new applications • Offers a guide to the design and synthesis of catalysts, and their applications in synthesis of polymers • Includes the information essential for choosing the appropriate reactions to maximize yield of polymer synthesized • Presents new chapters on vanadium catalysts, Ziegler catalysts, laboratory homopolymerization, and copolymerization

Download or read book Olefin Polymerization written by Walter Kaminsky and published by Wiley-VCH. This book was released on 2006-08-18 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: With an enormous velocity, olefin polymerization has expanded to one of the most significant fields in polymers since the first industrial use about 50 years ago. In 2005, 100 million tons of polyolefins were produced - the biggest part was catalyzed by metallorganic compounds. The Hamburg Macromolecular Symposium 2005 with the title "Olefin Polymerization" involved topics such as new catalysts and cocatalysts, kinetics, mechanism and polymer reaction engineering, synthesis of special polymers, and characterization of polyolefins. The conference combined scientists from different disciplines to discuss latest research results of polymers and to offer each other the possibility of cooperation. This is reflected in this volume, which contains invited lectures and selected posters presented at the symposium.

Download or read book Ethylene Polymerization with Homogeneous Fi Catalysts written by Saman Damavandi and published by LAP Lambert Academic Publishing. This book was released on 2012-06 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: Zirconium(IV) complexes bearing phenoxy-imino ligands are known to possess high ethene polymerisation activities after MAO activation. Depending on the ligand, the activities of the catalysts in polymerisation can vary. Depending on the polymerisation conditions and the electronic and steric properties of the catalyst ligands, low to high molar mass values with different polydispersity values can been observed. In order to discover the reasons for these differences, several zirconium(IV) complexes containing differently substituted phenoxy-imino derivatives ligands were synthesised with high yields and used as homogeneous catalysts in ethene polymerization. The experimental part consists mainly of development of new Group IV metal complexes bearing [O, N] ligands and therefore modification of the FI catalysts as well as their use as in ethylene polymerization. In this book the complex structures were designed so that the ligand frameworks could be fairly easily modified. Effects of the ligand framework as well as mechanical and fluxional behaviour of the complexes on the catalyst activity are discussed

Download or read book Non Flory Schulz Ethene Oligomerization with Titanium based Catalysts written by Patrick Jozef Wilhelmus Deckers and published by . This book was released on 2002* with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Alkene Polymerization Reactions with Transition Metal Catalysts written by Yury Kissin and published by Elsevier. This book was released on 2008-03-10 with total page 607 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the past 30 years, the field of alkene polymerization over transition metal catalysts underwent several major changes:1. The list of commercial heterogeneous Ziegler-Natta catalysts for the synthesis of polyethylene and stereoregular polyolefins was completely renewed affording an unprecedented degree of control over the polymer structure.2. Research devoted to metallocene and other soluble transition-metal catalysis has vastly expanded and has shifted toward complexes of transition metals with multidentate ligands.3. Recent developments in gel permeation chromatography, temperature-rising fractionation, and crystallization fractionation provided the first reliable information about differences between various active centers in transition-metal catalysts.4. A rapid development of high-resolution 13C NMR spectroscopy resulted in greatly expanded understanding of the chemical and steric features of polyolefins and alkene copolymers. These developments require a new review of all aspects of alkene polymerization reactions with transition-metal catalysts. The first chapter in the book is an introductory text for researchers who are entering the field. It describes the basic principles of polymerization reactions with transition-metal catalysts, the types of catalysts, and commercially manufactured polyolefins. The next chapter addresses the principal issue of alkene polymerization catalysis: the existence of catalyst systems with single and multiple types of active centers. The subsequent chapters are devoted to chemistry and stereochemistry of elemental reaction steps, structures of catalyst precursors and reactions leading to the formation of active centers, kinetics of polymerization reactions, and their mechanisms. The book describes the latest commercial polymerization catalysts for the synthesis of polyethylenes and polypropylene The book provides a detailed description of the multi-center nature of commercial Ziegler-Natta catalysts. The book devotes specialized chapters to the most important aspects of transition metal polymerization catalysts: the reactions leading to the formation of active centers, the chemistry and stereochemistry of elemental polymerization steps, reaction kinetics, and the polymerization mechanism. The book contains an introductory chapter for researchers who are entering the field of polymerization catalysis. It describes the basic principles of polymerization reactions with transition-metal catalysts and the types of commercially manufactured polyolefins and copolymersThe book contains over 2000 references, the most recent up to end of 2006.

Download or read book Applications of EPR and NMR Spectroscopy in Homogeneous Catalysis written by Evgenii Talsi and published by CRC Press. This book was released on 2017-04-07 with total page 229 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reviews advances in important and practically relevant homogeneous catalytic transformations, such as single-site olefin polymerizations and chemo- and stereo-selective oxidations. Close attention is paid to the experimental investigation of the active sites of catalytic oxidation systems and their mechanisms. Major subjects include the applications of NMR and EPR spectroscopic techniques and data obtained by other physical methods. The book addresses a broad readership and focus on widespread techniques available in labs with NMR and EPR spectrometers.

Download or read book Study of the Factors Affecting the Selectivity of Catalytic Ethylene Oligomerization written by Khalid Albahily and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past decade, advances in ethylene oligomerization have witnessed explosive growth of interest from both commercial and academic standpoint, with chromium metal invariably being the metal of preference. A common feature in this literature was the extended long debate regarding the mechanism, metal oxidation states responsible for selectivity and the role of the ligand. This thesis work embarked on the isolation and characterization of new active intermediates called "single component catalysts" (or self activating) to address two important questions: (1) how the catalyst precursors re-arrange upon activation and (2) the real oxidation state of the activated species. Four different ligands systems have been examined for this purpose. The first part is a study on the NPIIIN ligand which can be described as a dynamic and non-spectator ligand. Upon aluminum alkyl activation, a series of single component chromium catalysts for selective ethylene oligomerization and polymerization have been isolated, fully characterized and tested. New selective single component chromium(I) catalysts have also been isolated and tested positively for ethylene trimerization. The second part includes a new series of chromium complexes based on the NPVN ligand. This ligands enabled to obtain the first polymer-free extremely active catalytic system. In both NPN ligand systems, a new activation pathway was discovered by using vinyl Grignard reagent [(CH2=CH)MgCl] as activator and/or reducing agent. The third part explores new modified pyrrole-chromium complexes which were found to be highly active and selective ethylene trimerization catalysts. This part was a continuation of previous work from our lab to complete the mechanistic picture of this highly successful pyrrole-chromium catalyst independently commercialized by Phillips-Chevron and Mitsubishi. Interestingly upon aluminum alkyl treatment, the first example of a Schrock-type chromium ethylidene complex has been isolated and characterized and found to be a potent catalyst for selective ethylene trimerization. Finally, the other ligands introduced in this thesis are new systems called pyridine-SNS and Si-SNS that introduce some modification to the known commercial SNS catalyst (Sasol technology). The introduction of a pyridine ring or a silyl unit in the ligand scaffold has allowed to understand the mechanism of action of this remarkable system.