DOCSLIB.ORG

Hydrogenation of Ethylene on Metallic Catalysts

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Hydrogenation of Ethylene on Metallic Catalysts S ro Hating Bure* M “"“^ piu&« Ubwu, Ml ®min’ JUN 2 1 1S68 A 1 1 1 2 mbESD NATX INST OF STANDARDS & TECH R.I.C. NSRDS-NBS 13 NSRDS 11 021 46250 ™SRDS.NB^ QC100 -U573 V13;1968 C.1 sH *- NBS-PUB-C 1964 ^f#Cf DftU NBS 'USUCATfONS Hydrogenation of Ethylene Metallic Catalysts U.S. DEPARTMENT OF COMMERCE NATIONAL BUREAU OF STANDARDS National Standard Reference Data Series National Bureau of Standards National Standard Reference Data System, Plan of Operation, NSRDS-NBS 1 — 15 cents* Thermal Properties of Aqueous Uni-univalent Electrolytes NSRDS-NBS 2 — 45 cents* Selected Tables of Atomic Spectra, Atomic Energy Levels and Multiplet Tables — Si II, Si ill, Si iv, NSRDS-NBS 3, Section 1—35 cents* Selected Tables of Atomic Spectra, Atomic Energy Levels and Multiplet Tables — Si I NSRDS — NBS 3, Section 2 — 20 cents* Atomic Transition Probabilities, Volume I, Hydrogen Through Neon, NSRDS-NBS 4 — $2.50* The Band Spectrum of Carbon Monoxide, NSRDS-NBS 5 — 70 cents* Tables of Molecular Vibrational Frequencies. Part 1, NSRDS-NBS 6 — 40 cents* High Temperature Properties and Decomposition of Inorganic Salts. Part 1. Sulfates, NSRDS-NBS 7-35 cents* Thermal Conductivity of Selected Materials, NSRDS-NBS 8 — $1.00* Tables of Biomolecular Gas Reactions, NSRDS-NBS 9 — $2.00* Selected Values of Electric Dipole Moments for Molecules in the Gas Phase, NSRDS- NBS 10 — 40 cents* Tables of Molecular Vibrational Frequencies, Part 2, NSRDS-NBS 11 — 30 cents* Tables for the Rigid Asymmetric Rotor: Transformation Coefficient from Symmetric to Asymmetric Bases Expectation Values of P\ and 4 NSRDS-NBS 12 — in press. and P , * Send orders with remittance to: Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402. Remittances from foreign countries should include an additional one-fourth of the purchase price for postage. UNITED STATES DEPARTMENT OF COMMERCE Alexander B. Trowbridge, Secretary, NATIONAL BUREAU OF STANDARDS A. V. Astin, Director Hydrogenation of Ethylene on Metallic Catalysts Juro Horiuti* and Koshiro Miyahara* Hokkaido University Sapporo, Japan *Prepared under contract at the Hokaido University Sapporo, Japan NSRDS NSRDS-NBS 13 National Standard Reference Data Series- National Bureau of Standards 13 (Category 6 — Chemical Kinetics) Issued For Sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 — Price $1.00 NATIONAL BUREAU OF STANDARDS JUN 9 1970 Od ICO 1 , 6^5 73 no 13 17^8 CLO+>' ^ Library of Congress Catalog Card Number: 67-60071 Foreword The National Standard Reference Data System is a Government-wide effort to provide for the technical community of the United States effective access to the quantitative data of physical science, critically evaluated and compiled for convenience, and readily accessible through a variety of distribution channels. The System was established in 1963 by action of the President’s Office of Science and Technology and the Federal Council for Science and Technology. The responsibility to administer the System was assigned to the National Bureau of Standards and an Office of Standard Reference Data was set up at the Bureau for this purpose. Since 1963, this Office has developed systematic plans for meeting high-priority needs for reliable reference data. It has undertaken to coordinate and integrate existing data evaluation and compilation -activities (primarily those under sponsorship of Federal agencies) into a comprehensive program, supplementing and expanding technical coverage when necessary, establishing and maintaining standards for the output of the participating groups, and providing mechanisms for the dissemina- tion of the output as required. The System now comprises a complex of data centers and other activities, carried on in Government agencies, academic institutions, and nongovernmental laboratories. The independent operational status of existing critical data projects is maintained and encouraged. Data centers that are components of the NSRDS produce compilations of critically evaluated data, critical reviews of the state of quantitative knowledge in specialized areas, and computations of useful functions derived from standard reference data. In addition, the centers and projects establish criteria for evaluation and compilation of data and make recommendations on needed modifications or extensions of experimental techniques. Data publications of the NSRDS take a variety of physical forms, including books, pamphlets, loose-leaf sheets and computer tapes. While most of the compilations have been issued by the Government Printing Office, several have appeared in scientific journals. Under some circum- stances, private publishing houses are regarded as appropriate primary dissemination mechanisms. The technical scope of the NSRDS is indicated by the principal categories of data compilation projects now active or being planned: nuclear properties, atomic and molecular properties, solid state properties, thermodynamic and transport properties, chemical kinetics, colloid and surface properties, and mechanical properties. An important aspect of the NSRDS is the advice and planning assistance which the National Research Council of the National Academy of Sciences-National Academy of Engineering provides. These services are organized under an overall Review Committee which considers the program as a whole and makes recommendations on policy, long-term planning, and international collabora- tion. Advisory Panels, each concerned with a single technical area, meet regularly to examine major portions of the program, assign relative priorities, and identify specific key problems in need of further attention. For selected specific topics, the Advisory Panels sponsor subpanels which make detailed studies of users’ needs, the present state of knowledge, and existing data resources as a basis for recommending one or more data compilation activities. This assembly of advisory services contributes greatly to the guidance of NSRDS activities. The NSRDS-NBS series of publications is intended primarily to include evaluated reference data and critical reviews of long-term interest to the scientific and technical community. A. V. ASTIN, Director. Ill 5 -f , . D Contents Page Page 1. Introduction 1 12.2. Expressions for a E and a H 41 2. Reproducibility of observations 2 12.3. Practical expressions of k(s) 42 3. Catalytic activity of various pure metals and alloys 8 12.4. Rate equations in terms of k(s) 43 4. Reaction kinetics of catalyzed hydrogenation 13 12.5. Steady state of catalyzed hydrogenation 43 5. Reactions associated with the catalyzed hydrogenation... 17 12.6. Rates of reaction associated with the catalyzed 5.1. Experimental methods 18 hydrogenation 46 5.2. Modern observations 20 13. Estimate of A(s)’s 48 6. Isotopic effect on hydrogenation rate 25 13.1. Estimate of A(I a ) 48 7. Supported catalysts 27 13.2. Estimate of A(I b) 49 8. Carbided catalysts 30 13.3. Estimates of Ar(II) and A(III) 49 9. Reaction mechanisms 32 13.4. Rates based on the estimated A(s)’s 50 . 9.1. Dissociative mechanism 32 14. Application of the theory of the associative mechanism. 53 9.2. Associative mechanism 32 14.1. Switchover in the rate-determining step 53 9.3. Twigg and Rideal’s mechanism 34 14.2. Activation heat of hydrogen exchange 53 9.4. Jenkins and Rideal’s mechanism 35 14.3. Retardation of parahydrogen conversion and ‘H 2— 2 9.5. Redistribution mechanism 36 equilibration by the presence of ethylene 54 9.6. Adsorbed state of intermediates 36 14.4. The relation between equilibrium fraction, u, and 12.1. 10. Current theoretical treatments 36 deuterium atom fraction, xH , of hydrogen 55 10.1. Outline 36 14.5. Changes in VA ’s with temperature and partial pres- 10.2. Critical review of current treatment 38 sures of reactants 56 11. Statistical mechanical formulation of rates 39 14.6. “Random distribution” of deuterium in ethylene and 11.1. Outline 39 ethane in the deuteration of light ethylene 57 11.2. Function a, 40 14.7. Isotopic effect on hydrogenation rate 58 12. Statistical mechanical formulation of the associative 15. Application of the theory of absolute rates 59 mechanism 41 16. Concluding remark 61 Formulation of k(s) 41 17. References 61 V Hydrogenation of Ethylene on Metallic Catalysts Juro Horiuti and Koshiro Miyahara Reaction rate data for the catalyzed hydrogenation of ethylene, primarily in the presence of un- supported metallic catalysts, are cirtically reviewed. Reaction mechanisms are discussed in detail, and a statistical mechanical treatment of the reaction is given, according to the generalized theory of reaction starting from the well-known procedure of Glasstone, Laidler, and Eyring. Data for single- element catalysts and alloys are included and interpreted, as are~~data illustrating differences due to the physical form of the catalyst (film, foil, wire, powder, and some supported systems). Problems are discussed concerning reproducibility of experimental results over repeated runs, and as a function of catalyst pretreatment. The data is analyzed in 29 graphs and 29 tables, some of which are very extensive. The bibliography includes 141 references. Key Words: Critical data, ethylene, hydrogenation, metallic catalysts, reaction mechanisms, reaction rates. 1. Introduction The catalyzed hydrogenation of ethylene in the The character of catalyzed hydrogenation depends presence of metallic catalysts, especially nickel, further on the form and condition of the catalyst, has been a subject of intensive investigations, as i.e., differs for evaporated films, powders, wires, a prototype of catalyzed hydrogenations of the sort, and plates or catalyst supported on some dispersed since its discovery by Sabatier and Senderens [l]. 1 medium, e.g., alumina or silica gel. For instance, The catalyzed hydrogenation was found to be ethylene is polymerized over nickel catalyst sup- associated with parahydrogen conversion [2], which ported on kieselguhr but not over unsupported turned out to be a useful profile of the reaction. nickel powder. Moreover, some alloy catalysts are In 1932 deuterium appeared as a powerful tool for considerably more active than either of their revealing further profiles of the reaction. These components.
Load more

Recommended publications
  • Ethylene Dichloride (Edc) Handbook
    ETHYLENE DICHLORIDE (EDC) HANDBOOK OXYCHEM TECHNICAL INFORMATION 11/2014 Dallas-based Occidental Chemical Corporation is a leading North American manufacturer of basic chemicals, vinyls and performance chemicals directly and through various affiliates (collectively, OxyChem). OxyChem is also North America's largest producer of sodium chlorite. As a Responsible Care® company, OxyChem's global commitment to safety and the environment goes well beyond compliance. OxyChem's Health, Environment and Safety philosophy is a positive motivational force for our employees, and helps create a strong culture for protecting human health and the environment. Our risk management programs and methods have been, and continue to be, recognized as some of the industry's best. OxyChem offers an effective combination of industry expertise, experience, on line business tools, quality products and exceptional customer service. As a member of the Occidental Petroleum Corporation family, OxyChem represents a rich history of experience, top-notch business acumen, and sound, ethical business practices. 1 Table of Contents Page Introduction to Ethylene Dichloride ............................................................................................................ 3 Manufacturing .................................................................................................................................................. 3 Ethylene Dichloride (EDC) — Uses ................................................................................................................
    [Show full text]
  • Toxicological Profile for Ethylbenzene
    ETHYLBENZENE 151 5. PRODUCTION, IMPORT/EXPORT, USE, AND DISPOSAL 5.1 PRODUCTION Ethylbenzene is primarily produced by the alkylation of benzene with ethylene in liquid-phase slurry reactors promoted with aluminum chloride catalysts or by vapor-phase reaction of benzene with dilute ethylene-containing feedstock with a boron trifluoride catalyst supported on alumina (Cannella 2007; Clayton and Clayton 1981; HSDB 2009; Welch et al. 2005; Ransley 1984). Newer versions of the method employ synthetic zeolites in fixed-bed reactors as catalysts for alkylation in the liquid phase or narrow pore synthetic zeolites in fixed-bed reactors in the vapor phase (Welch et al. 2005). Other methods of manufacturing ethylbenzene include preparation from acetophenone, dehydrogenation of naphthenes, catalytic cyclization and aromatization, separation from mixed xylenes via fractionation, reaction of ethylmagnesium bromide and chlorobenzene, extraction from coal oil, and recovery from benzene-toluene-xylene (BTX) processing(Clayton and Clayton 1981; HSDB 2009; Ransley 1984; Welch et al. 2005). Commercial grades of ethylbenzene may contain small amounts of m-xylene, p-xylene, cumene, and toluene (HSDB 2009). Ethylbenzene is traditionally ranked as one of the top 50 chemicals produced in the United States. Table 5-1 shows the historical production volumes of ethylbenzene from 1983 to 2005 (C&EN 1994a, 1994b, 1995, 2006; Kirschner 1995). Table 5-2 lists the facilities in each state that manufacture or process ethylbenzene, the intended use, and the range of maximum amounts of ethylbenzene that are stored on site. There are currently 3,755 facilities that produce, process, or use ethylbenzene in the United States. The data listed in Table 5-2 are derived from the Toxics Release Inventory (TRI06 2008).
    [Show full text]
  • ETHYLENE from METHANE (January 1994)
    Abstract Process Economics Program Report No. 208 ETHYLENE FROM METHANE (January 1994) This report evaluates two routes for the production of ethylene from methane: the direct synthesis based on the oxidative coupling of methane, and the less direct chemistry of converting methanol (which is derived from methane via synthesis gas) in the presence of an aluminophosphate molecular sieve catalyst. Our evaluations indicate that at the present state of development, the economics of both routes are unattractive when compared with the steam pyrolysis of hydrocarbons. We analyze the results of our evaluations to define the technical targets that must be attained for success. We also present a comprehensive technical review that examines not only the two routes evaluated, but also some of the more promising alternative approaches, such as synthesis gas conversion via a modified Fischer-Tropsch process, ethanol synthesis by the homologation of methanol, and ethylene production via methyl chloride. This report will be of interest to petrochemical companies that produce or consume ethylene and to energy-based companies (or equivalent government organizations in various countries) that have access to or control large resources of methane-rich natural gas. PEP’91 SCN CONTENTS 1 INTRODUCTION 1-1 2 SUMMARY 2-1 TECHNICAL REVIEW 2-1 Oxidative Coupling 2-1 Methanol Conversion to Ethylene 2-3 Modified Fischer-Tropsch (FT) Process 2-3 Methanol Homologation 2-3 Conversion via Methyl Chloride 2-4 SRI’S PROCESS CONCEPTS 2-4 Ethylene from Methane by Oxidative
    [Show full text]
  • Acetylene and Ethylene Hydrogenation on Alumina Supported Pd-Ag Model Catalysts
    Catalysis Letters Vol. 108, Nos. 3–4, May 2006 (Ó 2006) 159 DOI: 10.1007/s10562-006-0041-y Acetylene and ethylene hydrogenation on alumina supported Pd-Ag model catalysts N.A. Khan,* S. Shaikhutdinov, and H.-J. Freund Department of Chemical Physics, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, Berlin 14195, Germany Received 20 December 2005; accepted 20 January 2006 Adsorption and co-adsorption of ethylene, acetylene and hydrogen on Pd-Ag particles, supported on thin alumina films, have been studied by temperature programmed desorption (TPD). The TPD results show that adding of Ag to Pd suppresses overall hydrogenation activity but increases selectivity towards ethylene, i.e. similar to that observed on real catalysts. The results are rationalized on the basis of a complex interplay between surface and subsurface hydrogen species available in the system, whereby the latter species are the most critical for total hydrogenation of acetylene to ethane. KEY WORDS: hydrogenation; bimetallic catalysts; acetylene; palladium; silver. The selective hydrogenation of acetylene is an alumina film both at low pressures (with TPD) and high industrially important catalytic process in the large-scale pressures (up to 1 bar, using gas chromatography [16– production of polyethylene, where a small quantity of 18]. Under both conditions, the ethylene hydrogenation acetylene (<3%) is present in ethylene feedstock. reaction was found to be structure insensitive. In Commercially, it is preferred to reduce the acetylene contrast, hydrogenation of 2-pentenes exhibited a sig- content to less than 10 ppm, which needs 99% acet- nificant particle size effect [19]. These studies have ylene conversion in the excess of ethylene [1].
    [Show full text]
  • Kinetic Study of the Selective Hydrogenation of Acetylene Over Supported Palladium Under Tail-End Conditions
    catalysts Article Kinetic Study of the Selective Hydrogenation of Acetylene over Supported Palladium under Tail-End Conditions Caroline Urmès 1,2, Jean-Marc Schweitzer 2, Amandine Cabiac 2 and Yves Schuurman 1,* 1 IRCELYON CNRS, UMR 5256, Univ Lyon, Université Claude Bernard Lyon 1, 2 avenue Albert Einstein, 69626 Villeurbanne Cedex, France; [email protected] 2 IFP Energies nouvelles, Etablissement de Lyon, Rond-point de l’échangeur de Solaize, BP3, 69360 Solaize, France; [email protected] (J.-M.S.); [email protected] (A.C.) * Correspondence: [email protected]; Tel.: +33-472445482 Received: 9 January 2019; Accepted: 31 January 2019; Published: 14 February 2019 Abstract: The kinetics of the selective hydrogenation of acetylene in the presence of an excess of ethylene has been studied over a 0.05 wt. % Pd/α-Al2O3 catalyst. The experimental reaction conditions were chosen to operate under intrinsic kinetic conditions, free from heat and mass transfer limitations. The data could be described adequately by a Langmuir–Hinshelwood rate-equation based on a series of sequential hydrogen additions according to the Horiuti–Polanyi mechanism. The mechanism involves a single active site on which both the conversion of acetylene and ethylene take place. Keywords: power-law; Langmuir–Hinshelwood; kinetic modeling; Pd/α-Al2O3 1. Introduction Ethylene is the largest of the basic chemical building blocks with a global market estimated at more than 140 million tons per year with an increasing growth rate. It is used mainly as precursor for polymers production, for instance polyethylene, vinyl chloride, ethylbenzene, or even ethylene oxide synthesis.
    [Show full text]
  • Acetone Sorption and Uptake Kinetic in Poly(Ethylene Terephthalate) C.C
    JPOL 3249 Polymer 40 (1999) 3487–3499 Acetone sorption and uptake kinetic in poly(ethylene terephthalate) C.C. McDowella,*, B.D. Freemana, G.W. McNeelyb aDepartment of Chemical Engineering, North Carolina State University, Raleigh, NC 27695-7905, USA bHoechst-Celanese Corporation, Spartanburg, SC, USA Received 11 March 1998; received in revised form 8 May 1998; accepted 18 May 1998 Abstract The sorption and kinetics of acetone uptake in solvent cast films of poly(ethylene terephthalate) are reported at 35ЊC for acetone pressures ranging from 0 to 7.3 cm Hg. The equilibrium sorption isotherm is well described by the dual-mode sorption model with the following 3 3 Ј : 3( )= 3 ¹1 parameters: k D ¼ 61 cm (STP)/(cm ·atm), CH ¼ 7 2cm STP cm , and b ¼ 50 atm . Sorption kinetics are described using a two-stage model which incorporates both Fickian diffusion and protracted polymer structural relaxation. The characteristic time associated with the relaxation process is essentially independent of acetone concentration and has an average value of approximately 15 hours. The fraction of sorption associated with polymer relaxation increases linearly with acetone concentration in the equilibrium-densified matrix of the polymer. Acetone diffusion coefficients increase with increasing acetone concentration. The concentration dependence of the acetone diffusion coefficient is well described by the dual-mobility model if the assumption of constant diffusion coefficients in the two modes is relaxed. ᭧ 1999 Elsevier Science Ltd. All rights reserved. Keywords: Sorption; Diffusion; Acetone 1. Introduction sorption model [7]. Liu and Neogi measured methylene chloride vapor sorption kinetics in PET over a wide range Poly(ethylene therephthalate) [PET] is an important of penetrant activity and observed Fickian mass uptake barrier material that is widely used to package foods and kinetics [8].
    [Show full text]
  • Decarbonization of Industrial Sectors: the Next Frontier
    Decarbonization of industrial sectors: the next frontier June 2018 Decarbonization of industrial sectors: the next frontier June 2018 Authored by: Arnout de Pee Dickon Pinner Occo Roelofsen Ken Somers Eveline Speelman Maaike Witteveen Preface The industrial sector is a vital source of wealth, prosperity, and social value on a global scale. Industrial companies produce about one-quarter of global GDP and employment, and make materials and goods that are integral to our daily lives, such as fertilizer to feed the growing global population, steel and plastics for the cars we drive, and cement for the buildings we live and work in. Industry also emits about 28 percent of global greenhouse gas (GHG) emissions, of which 90 percent are carbon dioxide (CO2) emissions. Between 1990 and 2014, GHG emissions from major sectors such as buildings, power, and transport increased by 23 percent (0.9 percent per year), while emissions from the industrial sector increased by 69 percent (2.2 percent per year). Over the last decades, the outlines of energy transition pathways have emerged in the buildings, power and transport sectors. These have been driven by technological breakthroughs and cost reduction. For industrial processes, such pathways are less well-defined. The energy transition in industry should be viewed in the context of global trends that will impact the demand for and preferred production routes of industrial products. There is an expected growth in resource demand, driven by an increase in middle class consumers of ~3 billion in the coming 20 years, as well as rapid urbanization. This coincides with growing constraints on key resources, such as copper and zinc, and environmental degradation, for instance from air pollution.
    [Show full text]
  • Ethene, Propene, Butene and Isoprene Emissions from a Ponderosa Pine Forest Measured by Relaxed Eddy Accumulation
    Atmos. Chem. Phys., 17, 13417–13438, 2017 https://doi.org/10.5194/acp-17-13417-2017 © Author(s) 2017. This work is distributed under the Creative Commons Attribution 3.0 License. Ethene, propene, butene and isoprene emissions from a ponderosa pine forest measured by relaxed eddy accumulation Robert C. Rhew1, Malte Julian Deventer1,*, Andrew A. Turnipseed2,*, Carsten Warneke3,4, John Ortega5, Steve Shen1, Luis Martinez6, Abigail Koss3,4, Brian M. Lerner3,4,a, Jessica B. Gilman3,4, James N. Smith5,b, Alex B. Guenther7, and Joost A. de Gouw3 1Department of Geography and Berkeley Atmospheric Sciences Center, University of California Berkeley, Berkeley, CA 94720-4740, USA 22B Technologies, Boulder CO 80301, USA 3Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado Boulder, Boulder CO 80309, USA 4NOAA Earth System Research Laboratory, Boulder, CO 80305, USA 5Atmospheric Chemistry Observations and Modeling (ACOM), National Center for Atmospheric Research, Boulder, CO 80301, USA 6Ernest F. Hollings Undergraduate Scholarship program, NOAA, Boulder, CO 80305, USA 7Department of Earth System Science, University of California Irvine, Irvine, CA 92697-3100, USA anow at: Aerodyne Research Inc., Billerica, MA 01821-3976, USA bnow at: Department of Chemistry, University of California Irvine, Irvine, CA 92697-2025, USA *These authors contributed equally to this work. Correspondence to: Robert C. Rhew ([email protected]) Received: 21 April 2017 – Discussion started: 4 May 2017 Revised: 9 September 2017 – Accepted: 28 September 2017 – Published: 10 November 2017 Abstract. Alkenes are reactive hydrocarbons that influence tober flux, based on measurements and modeling, averaged local and regional atmospheric chemistry by playing impor- 62, 52, 24 and 18 µg m−2 h−1 for ethene, propene, butene tant roles in the photochemical production of tropospheric and isoprene, respectively.
    [Show full text]
  • Ethylene in Plant Growth
    Proc. Nat. Acad. Sci. USA Vol. 70, No. 2, pp. 591-597, February 1973 Ethylene in Plant Growth STANLEY P. BURG The Fairchild Tropical Garden, and University of Miami, Miami, Florida 33156 ABSTRACT Ethylene inhibits cell division, DNA syn- of ethylene in plant growth destined to be studied intensively thesis, and growth in the meristems of roots, shoots, and axillary buds, without influencing RNA synthesis. Apical again. dominance often is broken when ethylene is removed, ap- Effects of ethylene on cell division parently because the gas inhibits polar auxin transport ir- reversibly, thereby reducing the shoot's auxin content just When etiolated pea seedlings are grown continuously in the as if the apex had been removed. A similar mechanism presence of a trace of ethylene, the stem hardly elongates and may underly ethylene-induced release from dormancy of root growth is inhibited about 60% (refs. 2, 5, 6; Fig. 3). A buds, tubers, root initials, and seeds. Often ethylene in- hibits cell expansion within 15 min, but delays differentia- swollen zone develops behind the root tip, root hairs prolifer- tion so that previously expanding cells eventually grow to ate, and the root deflects plageotropically in the gravitational enormous size. These cells grow isodiametrically rather field (5-7); similar changes occur in the stem (2, 5, 6). The than longitudinally because their newly deposited cellu- major cause of the overall growth inhibition is cessation or lose microfibrils are laid down longitudinally rather than retardation of the mitotic process in the meristems of the radially. Tropistic responses are inhibited when ethylene root, reversibly and rapidly prevents lateral auxin transport.
    [Show full text]
  • Ethylene Cas N°: 74-85-1
    OECD SIDS ETHYLENE FOREWORD INTRODUCTION ETHYLENE CAS N°: 74-85-1 UNEP PUBLICATIONS OECD SIDS ETHYLENE SIDS INITIAL ASSESSMENT PROFILE CAS No. 74-85-1 CHEMICAL NAME Ethylene STRUCTURAL FORMULA H H C C H H CONCLUSIONS Environment: Ethylene is, due to its physical and chemical properties released mainly into the atmospheric compartment. About three quarters of atmospheric ethylene originates from natural sources, while one quarter is from anthropogenic sources. The main anthropogenic release is from burning of hydrocarbons and biomass. It has been well documented through relevant toxicity studies that the minute amounts measured in water implies little environmental hazard to the organisms in this compartment. In the terrestrial compartment, the vegetation has proven highly susceptible to this gas, probably through a mechanism related to the hormone function of ethylene in plants. Ethylene levels in urban areas have reached levels which inhibit growth of certain plant species. This is of concern both for decorative plants and agriculture in exposed areas. This is mainly due to incomplete burning of coal and petrol products in urban areas. The industrial emission is a minor contribution to total emissions and effects on vegetation are only expected close to production and processing plants. Human Health: Relevant studies have indicated a low toxicity of ethylene and no risk to human health has been identified neither from occupational exposure nor exposure of general public, either exposed directly or indirectly via the environment. However, metabolic studies in animals and man have revealed that ethylene is metabolised to ethylene oxide which is known to have carcinogenic and mutagenic effects.
    [Show full text]
  • (Pahs) Coming from Pyrolysis in Low-Pressure Gas Carburizing Conditions Tsilla Bensabath, Hubert Monnier, Pierre-Alexandre Glaude
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Archive Ouverte en Sciences de l'Information et de la Communication Detailed kinetic modeling of the formation of toxic polycyclic aromatic hydrocarbons (PAHs) coming from pyrolysis in low-pressure gas carburizing conditions Tsilla Bensabath, Hubert Monnier, Pierre-Alexandre Glaude To cite this version: Tsilla Bensabath, Hubert Monnier, Pierre-Alexandre Glaude. Detailed kinetic modeling of the for- mation of toxic polycyclic aromatic hydrocarbons (PAHs) coming from pyrolysis in low-pressure gas carburizing conditions. Journal of Analytical and Applied Pyrolysis, Elsevier, 2016, 122, pp.342-354. 10.1016/j.jaap.2016.09.007. hal-01510237 HAL Id: hal-01510237 https://hal.archives-ouvertes.fr/hal-01510237 Submitted on 19 Apr 2017 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Title: Detailed kinetic modeling of the formation of toxic polycyclic aromatic hydrocarbons (PAHs) coming from pyrolysis in low-pressure gas carburizing conditions Authors: Tsilla Bensabatha,b
    [Show full text]
  • Oxychlorination of Ethylene with Copper Chloride Catalyst*
    Oxychlorination of Ethylene with Copper Chloride Catalyst* Naoya Kominami**, Kusuo Kawarazaki**, Yoshiaki Yamazaki** Tokio Sakurai** Summary: In the oxychlorination of C2H4, copper chloride on the active carbon has a higher activity than catalysts on other sorts of carrier. Examinations were made as to what relations exist between the selectivity of 1, 2-dichloroethane and composition of supplied gas and the reaction temperature. Two ranges in which the selectivity of 1, 2-dichloroethane does not vary and CO2 produced in large quantity were observed. The breaking point of both range depends on the mole ratio of HCl/C2H4 in the supplied gas and the reaction temperature. When the reaction is performed with the supplied gas having higher than 2 mole ratio of HCl/C2H4 the oxide-forming range does not appear. The forming rate of 1, 2-dichloroethane is shown by the following equation at chloride-forming range, r=kPC2H4PHCl0.2. Considering the rate equation shown above, the change of catalytic state and the results of the pulse technique, it is reduced that the mechanism of the oxychlorination of C2H4 with copper chloride catalyst is consisted of the follow- ing two equations, C2H4+2CuCl2→C2H4Cl2+Cu2Cl2 (a) Cu2Cl2+2HCl+1/2O2→2CuCl2+H2O (b) and the former is rate determining step. Introduction The authors have found that a high acti- As to synthesis of 1, 2-dichloroethane there vity at low temperatures can be obtained are many known methods using copper by using an active carbon carrier, and also chloride; for example, a method in which obtained some knowledge about the mecha- copper chloride is used as a chlorinating re- nism of the said catalyst, which are reported agent and the reduced copper chloride con- hereinafter.
    [Show full text]