Download or read book Catalytic Hydrogenation of Nitrile Rubber in High Concentration Solution written by Ting Li and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Chemical modification is an important way to improve the properties of existing polymers, and one of the important examples is the hydrogenation of nitrile butadiene rubber (NBR) in organic solvent by homogeneous catalysis in order to extend its application. This process has been industrialized for many years to provide high performance elastomers (HNBR) for the automotive industry, especially those used to produce components in engine compartments. In the current commercial process, a batch reactor is employed for the hydrogenation step, which is labor intensive and not suitable for large volume of production. Thus, novel hydrogenation devices such as a continuous process are being developed in our research group to overcome these drawbacks. In order to make the process more practical for industrial application, high concentration polymer solutions should be targeted for the continuous hydrogenation. However, many problems are encountered due to the viscosity of the high concentration polymer solution, which increases tremendously as the reaction goes on, resulting in severe mass transfer and heat transfer problems. So, hydrogenation kinetics in high concentration NBR solution, as well as the rheological properties of this viscous solution are very essential and fundamental for the design of novel hydrogenation processes and reactor scale up. In the present work, hydrogenation of NBR in high concentration solution was carried out in a batch reactor. A commercial rhodium catalyst, Wilkinson's catalyst, was used with triphenylphosphine as the co-catalyst and chlorobenzene as the solvent. The reactor was modified and a PID controller was tuned to fit this strong exothermic reaction. It was observed that when NBR solution is in a high concentration the kinetic behavior was greatly affected by mass transfer processes, especially the gas-liquid mass transfer. Reactor internals were designed and various agitators were investigated to improve the mechanical mixing. Experimental results show that the turbine-anchor combined agitator could provide superior mixing for this viscous reaction system. The kinetic behavior of NBR hydrogenation under low catalyst concentration was also studied. It was observed that the hydrogenation degree of the polymer could not reach 95% if less than 0.1%wt catalyst (based on polymer mass) was used, deviating from the behavior under a normal catalyst concentration. The viscosity of the NBR-MCB solutions was measured in a rotational rheometer that has a cylinder sensor under both room conditions and reaction conditions. Parameters that might affect the viscosity of the solutions were studied, especially the hydrogenation degree of polymer. Rheological properties of NBR-MEK solutions, as well as NBR melts were also studied for relevant information. It is concluded that the hydrogenation kinetics deviates from that reported by Parent et al. [6] when polymer is in high concentration and/or catalyst is in low concentration; and that the reaction solution (HNBR/NBR-MCB solution) deviates from Newtonian behavior when polymer concentration and hydrogenation degree are high.

Download or read book Catalytic Hydrogenation of Nitrile Butadiene Rubber Using Ir COD PCy3 py PF6 Catalyst written by Jianzhong Hu and published by . This book was released on 2003 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Catalytic Hydrogenation of Nitriles written by Richard Evans Juday and published by . This book was released on 1943 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Direct Catalytic Hydrogenation of Unsaturated Diene based Polymers in Latex Form written by Zhenli Wei and published by . This book was released on 2006 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt: The direct catalytic hydrogenation of nitrile butadiene rubber (NBR) in latex form was studied as a model system for the development of a new latex hydrogenation process for the modification of unsaturated diene-based polymers. NBR is a synthetic rubber of copolymerized acrylonitrile and butadiene produced in latex form by emulsion polymerization. The catalytic hydrogenation of NBR is an important post-polymerization process resulting in a more stable and tougher derivative, hydrogenated NBR (HNBR), which has been widely used in the automotive and oil drilling industry. The present commercial process involves a number of cumbersome steps to obtain solid NBR from the latex and subsequent dissolution of the solid NBR in a large amount of organic solvent followed by solvent recovery after coagulation of the hydrogenated NBR. Since NBR is produced in latex form, it is very desirable to directly hydrogenate NBR in the latex form which will significantly simplify the hydrogenation process and facilitate subsequent applications. As an economical and environmentally benign alternative to the commercial processes based on the hydrogenation of NBR in organic solution, this direct latex hydrogenation process is of special interest to industry. The objective of this project is to develop an efficient catalytic system in order to realize the direct catalytic hydrogenation of NBR in latex form.

Download or read book Design Modeling and Analysis of a Continuous Process for Hydrogenation of Diene Based Polymers Using a Static Mixer Reactor written by Chandra Mouli R. Madhuranthakam and published by . This book was released on 2007 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrogenated nitrile butadiene rubber (HNBR) which is known for its excellent elastomeric properties and mechanical retention properties after long time exposure to heat, oil and air is produced by the catalytic hydrogenation of nitrile butadiene rubber (NBR). Hydrogenation of NBR is carried out preferably in solution via homogeneous catalysis. As yet, it is being commercially produced in a semi-batch process where gaseous hydrogen continuously flows into a batch of reactant polymer. Several catalysts have been exploited successfully for the hydrogenation of NBR in organic solvents, which include palladium, rhodium, ruthenium, iridium and osmium complexes. Owing to the drawbacks of batch production (such as time taken for charging and discharging the reactants/products, heating and cooling, reactor clean up), and the huge demand for HNBR, a continuous process is proposed where potential time saving is possible in addition to the high turn over of the product.

Download or read book Handbook of Engineering Polymeric Materials written by P. Cheremisinoff and published by CRC Press. This book was released on 1997-07-25 with total page 928 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presenting practical information on new and conventional polymers and products as alternative materials and end-use applications, this work details technological advancements in high-structure plastics and elastomers, functionalized materials, and their product applications. The book also provides a comparison of manufacturing and processing techniques from around the world. It emphasizes product characterization, performance attributes and structural properties.

Download or read book A Study of Non catalytic Hydrogenation of Natural Rubber written by Jareerat Samran and published by . This book was released on 2005 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrogenation is one of the most efficient methods to alter and improve the physical properties of unsaturated polymers and to produce a new material. The aim of this research is to transform partially the unsaturated part of natural rubber (NR) into saturated moiety in order to improve its thermal and oxidative properties and to widen its area of applications. In this study, non-catalytic hydrogenation process was applied by using diimide generated in situ from two types of hydrogenating agent i.e. thermal decomposition of p-tolueriesulfonylhydrazide (TSH) and oxidation of hydrazine (N2H4) by hydrogen peroxide (H2O2). The chemical structure of the hydrogenated rubbers was analyzed by vibrational and resonance spectroscopies i.e. FTIR, Raman, 1H- and 13C-NMR. First, the hydrogenation of NR and its modified form as epoxidized NR (ENR) was performed by using TSH in xylene solution at 135°C. The molar ratio of [TSH]:[C=C] equal to 2 was used for hydrogenation of NR and four different types of ENR i.e.ENR-10, ENR-22, ENR-30 and ENR-40, containing 10, 22, 30 and 40% mole of epoxide content, respectively. The quantitative measurements on fraction of saturated units determined by Raman, 1H-NMR in liquid state and 13C-NMR in solid state gave similar results which indicated that percent hydrogenation increased with increasing reaction time and about 80-89 % hydrogenation was obtained at 8h. While in the case of ENRs, the percent hydrogenation is approximately 93-98%. Cis-trans isomerization was also observed by 1H-NMR in liquid state and 13C_NMR both in liquid and solid state. Sorne side reaction occurred i.e. chain degradation of both NR and ENRs which might be due to a relatively high temperature process. In the case of hydrogenation of ENRs, formation of furan structure and fixation of p-toluenesulfinic acid (TSOH) by-product were detected by FTIR. For hydrogenation using (N2H4) and (H2O2), NR in the original form of latex was used. Various parameters affecting the hydrogenation reaction were investigated i.e. reaction time and temperature, amount of reactants, and dry rubber content. The hydrogenation progress could be monitored by means of NMR in liquid state as function of reaction condition. The results indicated that the best result was obtained when equimolar ratio of (N2H4) and (H2O2) was used. With addition of varying hydrazine and hydrogen peroxide contents, the best condition of diimide reduction is achieved when their content is 1.5 times the amount C=C of the rubber. Molecular characteristics in the NR, ENR-l 0 and the hydrogenated rubbers were investigated by Raman and 13C-NMR in solid state techniques. The relative variation force constant as analyzed by Raman spectroscopy tends to increase with the hydrogenation level. It might be suggested that the higher stiffness of the rubber chains upon hydrogenation is correlated to the increased relative variation force constants. In cross-polarization (CP) experiment of HNR and HENR, it was found that the rate of cross polarization of methyl carbon in HENR-30(8) is highest with respect to methyl carbon in HNR(8) and HENR-IO(8). It is clear that the methyl carbon of HENR-30(8) has the least mobility due to more furan units and chemical fixation of TSOH on the rubber chains. Thermal properties studied by a differential scanning calorimetry revealed thermal improvement after hydrogenation, both in solution and in aqueous systems. Comparison of the thermal stability using thermogravimetric analyzer, under air and nitrogen atmosphere, showed the decomposition temperature of HNR in air is lower than that in nitrogen atmosphere. The thermal stability of ENR was also enhanced after hydrogenation. Rheological properties of HNR samples measured using RPA rheometer exhibited the storage and loss moduli of HNR97 sample with the highest value compared to HNR38 and HNR69 samples. For instance, the fully hydrogenated NR has a significant increment in the loss and storage moduli of the samples. By using Raman mapping technique, it revealed that the hydrogenation of NR is a random process at the micron level.

Download or read book Catalytic Hydrogenation and Reduction written by Edward Bradford Maxted and published by . This book was released on 1919 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ruthenium Based Hydrogenation and Frustrated Lewis Pair Chemistry written by Louie Fan and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the discovery of catalytic hydrogenation, the field of transition metal-based hydrogenation catalysis has grown significantly. Recently, main group systems have demonstrated the capability to perform some of the same catalytic processes. Frustrated Lewis pairs (FLP), the combination of sterically encumbered Lewis acids and Lewis bases, are able to activate a variety of small molecules. The research presented in this thesis investigates main group and transition metal-based catalytic hydrogenation, as well as stoichiometric transformations with main group systems. A variety of ruthenium N-heterocyclic carbene (NHC) complexes were generated with polyethylene glycol (PEG) on the NHC to impart water-solubility. These hydrogenation catalysts were used to hydrogenate nitrile butadiene rubber (NBR) to hydrogenated nitrile butadiene rubber (HNBR). The PEG lengths had minimal effect on the conversion of NBR in solution phase. For the hydrogenation of NBR latex, a correlation was observed between the PEG length and the activity. A family of phosphinimines with different steric and electronic properties was synthesized from the Staudinger reaction between alkynyl-phosphines and azido-phosphine-boranes. Cyclization of these products can be induced thermally or by the addition of catalytic amounts of B(C6F5)3. Upon cyclization, a net trans-hydroboration was observed on the exocyclic alkene. A novel geminal boron-sulfur FLP was synthesized from the hydroboration of sulfur-alkynes. These systems demonstrated FLP-type chemistry such as the activation of terminal alkynes. Interestingly, the frustration was a result of the steric conflict between the tert-butyl substituent on the carbon and the p-tolyl substituent on the Lewis basic sulfur. This FLP-type reactivity can altered upon isomerization of the complex, forming the classical Lewis pair adduct. Finally, metal-free transformation of 3-ethylidene-6-vinyltetrahydro-2H-pyran-2-one was investigated. The Lewis acid B(C6F5)3 was shown to catalytically hydrogenate the allyl functionality of the substrate, as well as catalytic hydrosilylation of the conjugated alkene.

Download or read book Handbook of Elastomers Second Edition written by Anil K. Bhowmick and published by CRC Press. This book was released on 2000-11-02 with total page 954 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Provides the latest authoritative research on the developments, technology, and applications of rubbery materials. Presents structures, manufacturing techniques, and processing details for natural and synthetic rubbers, rubber-blends, rubber composites, and thermoplastic elastomers. 80% revised and rewritten material covers major advances since publication of the previous edition."

Download or read book The Catalytic Hydrogenation of Rubber written by Harry Elmer Albert and published by . This book was released on 1939 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Practical Catalytic Hydrogenation written by Morris Freifelder and published by John Wiley & Sons. This book was released on 1971 with total page 686 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Catalytic Hydrogenation of Natural Rubber written by D. R. Burfield and published by . This book was released on 1985 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Catalytic Hydrogenation of Nitriles to Amines written by Sarah Glennie and published by . This book was released on 2006 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Polymer Science written by I. S. Bhardwaj and published by . This book was released on 1994 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt: Papers presented at the Polymers '94, a symposium held at Indian Petrochemicals Corporation, Vadodara, February 8-10, 1994.

Download or read book Kinetic and Mechanistic Studies on the Liquid phase Hydrogenation of Nitriles and Dinitriles Over Cobalt based Catalysts written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Primary amines are important base intermediates, which are used in the production of pesticides and pharmaceuticals. The catalytic hydrogenation of nitriles is an important synthesis route to amines. To understand how to improve selectivity and reaction rate, physico-chemical and kinetic studies were combined. Investigations into the elemantary steps occurring on the surface of the cobalt catalyst showed that the adsorption properties of the nitriles and the amines formed strongly influence reaction rate and selectivity. It was demonstrated that the improved selectivity to the primary amine after LiOH modification of the catalyst was due to a decreased adsorption strength of the primary amine and a lower concentration of Lewis acid sites. In the hydrogenation of fatty nitriles high selectivity can be achieved after addition of ammonia only. The necessary boundary conditions were identified.

Download or read book Fourth Conference on Catalytic Hydrogenation and Analogous Pressure Reactions written by Paul Nels Rylander and published by . This book was released on 1973 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: