DOCSLIB.ORG

The Formation of Filamentous Carbon on Iron and Nickel Catalysts

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Formation of Filamentous Carbon on Iron and Nickel Catalysts JOURNAL OF CATALYSIS %,468-480 (1985) The Formation of Filamentous Carbon on Iron and Nickel Catalysts II. Mechanism A.J.H.M. KOCK, P. K. DE BOKX, E. BOELLAARD, W. KLOP, AND J. W. GEUS Department of Inorganic Chemistry, State University of Utrecht, Croesestraat 77A, 3522 AD Utrecht, The Netherlands Received May 31, 1984; revised February 18, 1985 The mechanism of filamentous carbon growth on iron and nickel catalysts has been studied using a combination of magnetic techniques and temperature-programmed hydrogenation. CO and CH4 were used as carburizing agents. It is concluded that high carbide contents are a prerequisite for the nucleation of filamentous carbon. The presence of a substoichiometric nickel carbide during steady-state growth is established. In the case of iron the hexagonal a-Fe2C or .a’-Fe& is proposed to be the intermediate in filamentous growth. The driving force for carbon transport can be appreci- ated considering the presence of a gradient in the carbon content of nonstoichiometric car- bides. 0 1985 Academic press. inc. INTRODUCTION to an exothermic surface reaction was the driving force for whisker growth. In this In Part I (I) we presented evidence for model carbon segregated at the cold rear of the involvement of carbide intermediates in the particle, where the solubility of carbon filamentous carbon growth on iron and is smaller. A severe criticism of this model nickel catalysts. The characterization of is found in the occurrence of filamentous these carbides under growth conditions as growth during endothermic decomposition well as the mechanism leading to filament reactions. Baker et al. (9) have replied that growth is the subject of the present study, saturated hydrocarbons are known to de- A number of mechanisms explaining fila- compose via their dehydrogenated analogs. mentous carbon growth on transition Decomposition of the latter compounds is metals has been suggested (24). Carbon exothermic and, consequently, a mecha- can be transported by a surface diffusion nism involving thermal diffusion would not process or by bulk diffusion through the be contravened. This explanation, how- particle. Massaro and Petersen (5) showed ever, calls for separate sites where only the that surface diffusion of carbon on nickel endothermic dehydrogenation takes place. foils is negligibly small in the temperature Rostrup-Nielsen and Trimm (3), refer- range 620-970 K. Also the sparse data for ring to Wada et al. (IO), assumed that car- surface migration of hydrocarbon species bon species of different origin have a differ- indicate that carbon transport does not pro- ent solubility. Thus, carbon species at the ceed through surface diffusion of hydrocar- metal-gas interface originating from hydro- bon fragments (6). At present a growth carbon decomposition reactions have a model involving bulk diffusion through the higher solubility than carbon originating metal particle is generally accepted (7). The from graphite. The resulting concentration driving force responsible for this bulk diffu- gradient is thought to be responsible for sion, however, has not been unequivocally carbon transport. However, the physical established. basis for these different solubilities has not Baker et al. (2, 8) stated that a tempera- been clarified. ture gradient across the metal particle due Buyanov et al. (4, 11, 12) proposed a 468 0021-9517185 $3.00 Copyright 8 1985 by Academic Press, Inc. All rights of reproduction in any form reserved. FILAMENTOUS CARBON ON Fe AND Ni CATALYSTS, II 469 when the transport of carbon proceeds through interstitially dissolved carbon. Magnetic measurements enabled us to as- sess the presence of (intermediate) metal carbides during the different stages of car- bon deposition. The carbide content in the early stages of filamentous growth was monitored using in situ magnetization mea- surements. Carbon contents present during steady-state filamentous growth were quan- titatively determined using temperature- programmed hydrogenation (TPH). Combi- / nation with measurements of the saturation magnetization (MS) yielded information about the chemical nature of the carbon FIG. 1. Schematic diagram of apparatus for magnetic species. The identification of ferro/ferri- measurements: (1) sample holder, (2) cooler/heater, (3) magnetic phases was performed employing transportable electromagnet, (4) Helmholtz sensing thermomagnetic analysis (TMA). Implica- coils, (5) integrating device. tions for the mechanism of filamentous growth will be given. carbide-cycle mechanism: this invoked EXPERIMENTAL consecutive formation and decomposition of carbides, where carbon separated in the Apparatus latter step leads to the formation of fila- Magnetic measurements were performed ments. Thus, no longer interstitial carbon using a modified Weiss-extraction method with an extremely low (extrapolated) solu- (Fig. 1). Ferromagnetic samples could be bility was considered, but the carbon was magnetized in fields up to 0.52 MA m-l. supposed to have a carbidic nature. The magnetic field (H) was produced by a Previously (Z), we observed that during Newport Type A electromagnet with 60- carbon whisker growth on iron and nickel mm pole faces separated by a 46-mm gap. catalysts equilibria with carbides were at- Between the magnet poles two interrupted tained. Independently, we established the Helmholtz sensing coils were mounted co- presence of carbon at concentrations axially. These pick-up coils were 20 mm in greatly exceeding the solubility of intersti- diameter and each contained 18,000 turns tial carbon in iron as well as in nickel, in of insulated copper wire (diameter 0.1 mm). agreement with prior reports (13). Re- They were connected in series, but in an cently, for iron catalysts cementite (f3-Fe3C) opposite sense to minimize disturbances was proposed to be the catalyst for carbon caused by field fluctuations. Extraction of deposition (Sacco et al. (24)). Baker et al. the magnetized sample from the pick-up (9) observed no carbon whisker growth coil generates an induction voltage. The starting from &Fe$ at all, however. The time integral of the induction voltage corre- presence of Eckstrom-Adcock carbide sponds to the net change of magnetic flux at (Fe&) at the tip of carbon filaments has the pick-up coil. Integration was done after been demonstrated (15). amplification (1000X). Instead of displacing In this study we present experiments the specimen, in our modification of the which allow a discrimination to be made Weiss-extraction method the electromagnet between the mechanisms mentioned above. could be transported along two rails over It is very unlikely that a carbon content ap- any desired distance. The magnetization of proximating that of a carbide is attained, samples could be measured at temperatures 470 KOCK ET AL. ranging from 100 up to 740 K using an indi- where (I). For the nickel catalyst reported rect air cooler/heater. The quartz sample on in this paper the dispersion was esti- holder was connected to a conventional Py- mated to be 0.1 [the Langevin low-field esti- rex high-vacuum system, equipped with a mate (17) for the mean particle size (assum- quadrupole mass spectrometer (Leybold- ing spherical particles) was 5.4 nm]. The Heraeus Q 200). The sample holder was dispersion of the iron catalyst was esti- also suited for atmospheric flow experi- mated to be 0.02 from X-ray line broaden- ments allowing for simultaneous mass- ing, using the Scherrer equation. spectrometric gas analysis. Temperature- programmed experiments could be carried RESULTS out at heating rates ranging from 1.7 to 300 mK s-l. Nickel Catalysts In some experiments also a vibrating- A. Transient carburization behavior. To sample magnetometer was used. The prin- investigate the transient behavior of nickel ciple of this technique has been clearly out- catalyst particles concurrent with filamen- lined in Ref. (16). This apparatus enables tous carbon growth, the magnetization of a us to perform magnetization experiments freshly reduced 50 wt% NiBi catalyst at liquid-nitrogen temperature at a field (reduction temperature 870 K) was moni- strength up to 1.12 MA m-i. After the cata- tored as a function of time. As electron mi- lyst pretreatment (reduction or carburiza- croscopy (I) revealed that nickel particles tion) 50 mg of the catalyst was brought into with a diameter larger than 10 nm were in- the sample holder under a nitrogen atmo- volved exclusively in filament growth, the sphere to prevent oxidation of the sample. measurement of the magnetization should be performed under conditions that give Procedures and Catalysts high weighting to the larger particles. The Thermomagnetic analysis was performed moderate H/T values applied guarantees at the maximum field strength (0.52 MA that nickel atoms present in larger particles m-l). These analyses were carried out in a predominantly contribute to the observed helium atmosphere or in a flow of 10 ~01% magnetization. Figure 2 shows the time de- of hydrogen diluted with argon at a total pendence of the magnetization during car- flow rate of 0.14 cm3 s-i. The magnetically burization with 10 ~01% of methane in ni- monitored transient carburization experi- trogen at a flow rate of 0.8 cm3 s-i. The ments were also measured at the maximum magnetization was measured during 15 ks, field strength. To prevent displacement of while also after a period of 65 ks a final catalytic material during the magnetic mea- measurement was made. Methane was cho- surements the reactor bed was covered sen as the carburizing agent to prevent in- with a layer of quartz fragments. The satu- terference by Ostwald ripening of nickel ration magnetization at room temperature particles due to transport via Ni(COk. The was determined by linear extrapolation of magnetization was followed during carburi- the it4 versus l/H plot. zation at three different temperatures, viz. Temperature-programmed hydrogena- 576, 596, and 611 K. Initially a decrease of tion was performed at a heating rate of 0.1 the magnetization was observed. Having K s-l using a flow of 0.8 cm3 s-l of 10 ~01% passed through a minimum, the magnetiza- hydrogen in argon.
Load more

Recommended publications
  • Ultra Small-Mass AMS C Sample Preparation and Analyses At
    NIM B Beam Interactions with Materials & Atoms Nuclear Instruments and Methods in Physics Research B 259 (2007) 293–302 www.elsevier.com/locate/nimb Ultra small-mass AMS 14C sample preparation and analyses at KCCAMS/UCI Facility G.M. Santos *, J.R. Southon, S. Griffin, S.R. Beaupre, E.R.M. Druffel Earth System Science, University of California, Irvine, B321 Croul Hall, Irvine, CA 92697-3100, USA Available online 31 January 2007 Abstract We have developed techniques for accurately and precisely measuring samples containing less than a few hundred micrograms of car- bon, using a compact AMS system (NEC 0.5 MV 1.5SDH-1). Detailed discussions of the sample preparation, measurement setup, data analysis and background corrections for a variety of standard samples ranging from 0.002 to 1 mgC are reported. Multiple aliquots of small amounts of CO2 were reduced to graphite with H2 over pre-baked iron powder catalyst. A reduction reaction temperature of 450 °C was adopted for graphite samples below 0.05 mgC, rather than the usual 550 °C used on samples of 0.1–1 mgC. In our regular reactors (3.1 cm3), this reduction in temperature improved the graphite yield from 60 to 90–100% for samples ranging from 0.006– 0.02 mgC. The combination of lower reaction temperature with a reduced reactor volume (1.6 cm3) gave yields as high as 100% on graphite samples <0.006 mgC. High performance measurements on ultra-small samples are possible also due to a modified NEC MC-SNIC ion-source that generates CÀ currents of 1 lA per lg of carbon for samples in the 0.002 to 0.010 mgC range, combined with on-line measurement of 12C and 13C (AMS d13C) to correct machine-induced isotopic fractionation.
    [Show full text]
  • Filamentous Carbon Particles for Cleaning Oil Spills and Method of Production. DIV
    University of Central Florida STARS UCF Patents Technology Transfer 1-6-2009 Filamentous Carbon Particles for Cleaning Oil Spills and Method of Production. DIV Nazim Muradov University of Central Florida Find similar works at: https://stars.library.ucf.edu/patents University of Central Florida Libraries http://library.ucf.edu This Patent is brought to you for free and open access by the Technology Transfer at STARS. It has been accepted for inclusion in UCF Patents by an authorized administrator of STARS. For more information, please contact [email protected]. Recommended Citation Muradov, Nazim, "Filamentous Carbon Particles for Cleaning Oil Spills and Method of Production. DIV" (2009). UCF Patents. 191. https://stars.library.ucf.edu/patents/191 I lllll llllllll Ill lllll lllll lllll lllll lllll 111111111111111111111111111111111 US007473466Bl c12) United States Patent (10) Patent No.: US 7,473,466 Bl Muradov (45) Date of Patent: *Jan. 6, 2009 (54) FILAMENTOUS CARBON PARTICLES FOR FOREIGN PATENT DOCUMENTS CLEANING OIL SPILLS AND METHOD OF PRODUCTION WO WO 00/21878 412000 (75) Inventor: Nazim Muradov, Melbourne, FL (US) (73) Assignee: University of Central Florida Research OTHER PUBLICATIONS Foundation, Inc., Orlando, FL (US) Makoto Egashira, Hiroaki Katsuki, Yasuki Ogawa and Shohachi ( *) Notice: Subject to any disclaimer, the term ofthis Kawasumi, Whiskerization of carbon beads by vapor phase growth of patent is extended or adjusted under 35 carbon fibers to obtain sea urchin-type particles, Carbon, vol. 21, No. U.S.C. 154(b) by 333 days. 1, pp. 89-92, 1983.* Evans et al., Growth of Filamentary Carbon on Metallic Surfaces This patent is subject to a terminal dis­ During the Pyrolysis of Methane and Acetone in Carbon vol.
    [Show full text]
  • Paul Scherrer Institute Scientific Report 1998. Volume V
    ETOf-C//—^ fo / PAUL S CHER HER INSTITUT ISSN 1423-7342 March 1999 i J i I i i i i PSI • Scientific Report 1998 / Volume V General Energy Photo Cover View along the tubing system of a prototype Condensation Interface which was developed for the on-line measurement of heavy metal concentrations in hot gases. See article by Ch. Ludwig, S. Stuck! and A.J. Schuler Photo: Armin Muller, RSI PAULSCHERRER INSTITUT ISSN 1423-7342 March 1999 Scientific Report 1998 Volume V General Energy ed. by: Christina Daum and Jakob Leuenberger CH-5232 Villigen PSI Switzerland Phone: 056/310 21 11 Telefax: 056/310 21 99 http://www1.psi.ch/www_f5_hn/f5_home.html DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. TABLE OF CONTENTS Introduction 1 A. Wokaun Renewable Energies and Materials Cycles 3 The Influence of Chlorine on the Fate and Activity of Alkali Metals during the Gasification of 4 Wood R. Struis, C. von Scala, A. Schuler, S. Stuck! On-Board Conversion of Methanol to Dimethyl Ether as an Alternative Diesel Fuel 6 H. Armbruster, G. Heinzelmann, R. Struis, S. Stuck! Solar Thermal Production of Zinc: Program Strategy 8 A. Steinfeld, A. Weidenkaff, S. Moeller, R. Palumbo Economic Evaluation of the Solar Thermal Co-Production of Zinc, Synthesis Gas, and 10 Hydrogen A. Steinfeld, I. Spiewak (EC Joint Research Centre, Spain) Solar Production of Catalytic Filamentous Carbon by Thermal Decomposition of Hydro- 12 carbons and Carbon Monoxide V.A. Kirillov, G.G. Kuvshinov, Yu.l.
    [Show full text]
  • Carbon Materials in the Treatment of Soft and Hard Tissue Injuries
    EuropeanM. Blazewicz Cells and Materials V ol. 2. 2001 (pages 21-29) Carbon DOI: materials 10.22203/eCM.v002a03 in the treatment of soft and hard ISSN tissue 1473-2262 injuries CARBON MATERIALS IN THE TREATMENT OF SOFT AND HARD TISSUE INJURIES M. Blazewicz Department of Special Ceramics, University of Mining and Metallurgy, al. Mickiewicza 30, 30-059 Cracow, Poland Abstract Introduction Carbon-based implant materials are of interest because Over the past twenty-five years various carbon materials they are well accepted by the biological environment. have been investigated in many areas of medicine (Bohem, Carbon fibrous materials developed in the Department of 1966; Arru et al., 1987; Jockish et al., 1992; Vallana et Special Ceramics of the University of Mining and Metal- al., 1993; Blazewicz et al., 1994; Carranza-Bencano et lurgy in Cracow were tested in in vivo studies to deter- al., 2000). The large range of papers presented in scien- mine their influence on the living body. For comparative tific journals is related to the spectacular chemical and purposes, different carbon fibers were prepared and sub- physical properties of carbon materials. Carbon occurs in jected to different surface modifications. Carbon materi- different lattice forms, from amorphous through interme- als prepared in the form of braids were implanted in subcu- diate to crystalline, e.g., hexagonal or regular lattice dia- taneous tissue of rabbits and into skeletal muscle of rats. mond. The broad range of applications of carbon materi- Carbon fabrics were examined as scaffolds in reconstruc- als in medicine is also the outcome of many preparation tion of bone defects.
    [Show full text]
  • Part One Overview of Synthesis, Characterization, and Applications in Biomedicine
    1 Part One Overview of Synthesis, Characterization, and Applications in Biomedicine Nanomaterials for the Life Sciences Vol.9: Carbon Nanomaterials. Edited by Challa S. S. R. Kumar Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim ISBN: 978-3-527-32169-8 3 1 Carbon Nanomaterials: Synthetic Approaches Jean - Philippe Tessonnier 1.1 Introduction The strength of carbon nanomaterials lies in the fact that most of their properties can be modifi ed and adjusted, depending on the target application(s). The mor- phology, surface chemistry, as well as the physical properties of carbon nanoma- terials are all susceptible to change by tuning the synthesis procedures, or by employing post - treatments. As the possibilities are almost unlimited, not only the materials scientists but also (bio - )chemists and biologists have at their disposal an immense playground to invent new materials for electronics, transportation, energy production and storage, or medicine. In the latter case, carbon nanomateri- als – such as fullerenes, nanohorns, and nanotubes – have already contributed to the development of new biosensors, diagnostic tools, drugs, and therapies [1 – 4] . Although nanomaterials such as fullerenes or carbon nanotube s ( CNT s) are remarkably popular and already available from several suppliers – as in the case of any other chemical compound – their synthesis remains a dynamic fi eld of research. Today, improvements are continuously being made to increase the selectivity of desired nanomaterialsas, as well as their purity and quality. In the case of CNTs, much progress has been made in controlling their diameter, length, and chiral- ity – all of which may be critically important, depending on the desired application(s).
    [Show full text]
  • On Thermodynamic Equilibrium of Carbon Deposition from Gaseous C-H-O Mixtures: Updating for Nanotubes
    Rev Chem Eng 2017; 33(3): 217–235 Open Access Zdzisław Jaworski*, Barbara Zakrzewska and Paulina Pianko-Oprych On thermodynamic equilibrium of carbon deposition from gaseous C-H-O mixtures: updating for nanotubes DOI 10.1515/revce-2016-0022 Received April 29, 2016; accepted July 29, 2016; previously published 1 Introduction online August 26, 2016 The world energy infrastructure currently uses mainly Abstract: Extensive literature information on experimental fossil fuels such as hydrocarbons and various types of thermodynamic data and theoretical analysis for deposit- coal with steadily growing contribution from renewable ing carbon in various crystallographic forms is examined, energy sources as the energy economy based on hydrogen and a new three-phase diagram for carbon is proposed. as energy carrier is still in its infancy. One of the key prob- The published methods of quantitative description of lems associated with carbonaceous fuels is unfavorable gas-solid carbon equilibrium conditions are critically deposition of solid carbon from gaseous carbon-hydro- evaluated for filamentous carbon. The standard chemi- gen-oxygen (C-H-O) mixtures met in a range of industrial cal potential values are accepted only for purified single- processes (Rostrup-Nielsen 1997). The main sources of walled and multi-walled carbon nanotubes (CNT). Series depositing carbon were described in the literature as (i) of C-H-O ternary diagrams are constructed with plots of molecules of elemental carbon created in thermal crack- boundary lines for carbon deposition either as graphite or ing reactions in gas phase (Jankhah et al. 2008) and (ii) nanotubes. The lines are computed for nine temperature C-H-O compounds of various proportions of the elements, levels from 200°C to 1000°C and for the total pressure of decomposed on catalyst surfaces (Chen et al.
    [Show full text]
  • Heterogeneous Catalyst Deactivation and Regeneration: a Review
    Catalysts 2015, 5, 145-269; doi:10.3390/catal5010145 OPEN ACCESS catalysts ISSN 2073-4344 www.mdpi.com/journal/catalysts Review Heterogeneous Catalyst Deactivation and Regeneration: A Review Morris D. Argyle and Calvin H. Bartholomew * Chemical Engineering Department, Brigham Young University, Provo, UT 84602, USA; E-Mail: [email protected] * Author to whom correspondence should be addressed; E-Mail: [email protected]; Tel: +1-801-422-4162, Fax: +1-801-422-0151. Academic Editor: Keith Hohn Received: 30 December 2013 / Accepted: 12 September 2014 / Published: 26 February 2015 Abstract: Deactivation of heterogeneous catalysts is a ubiquitous problem that causes loss of catalytic rate with time. This review on deactivation and regeneration of heterogeneous catalysts classifies deactivation by type (chemical, thermal, and mechanical) and by mechanism (poisoning, fouling, thermal degradation, vapor formation, vapor-solid and solid-solid reactions, and attrition/crushing). The key features and considerations for each of these deactivation types is reviewed in detail with reference to the latest literature reports in these areas. Two case studies on the deactivation mechanisms of catalysts used for cobalt Fischer-Tropsch and selective catalytic reduction are considered to provide additional depth in the topics of sintering, coking, poisoning, and fouling. Regeneration considerations and options are also briefly discussed for each deactivation mechanism. Keywords: heterogeneous catalysis; deactivation; regeneration 1. Introduction Catalyst deactivation, the loss over time of catalytic activity and/or selectivity, is a problem of great and continuing concern in the practice of industrial catalytic processes. Costs to industry for catalyst replacement and process shutdown total billions of dollars per year. Time scales for catalyst deactivation vary considerably; for example, in the case of cracking catalysts, catalyst mortality may be on the order of seconds, while in ammonia synthesis the iron catalyst may last for 5–10 years.
    [Show full text]
  • Radiocarbon Dating of Glacier Ice
    The Cryosphere Discuss., doi:10.5194/tc-2016-160, 2016 Manuscript under review for journal The Cryosphere Published: 22 July 2016 c Author(s) 2016. CC-BY 3.0 License. Radiocarbon dating of glacier ice Chiara Uglietti 1,2,3 , Alexander Zapf 1,2,3†, Theo M. Jenk 1,3 , Sönke Szidat 2,3 , Gary Salazar 2, Margit Schwikowski 1,2,3 1Laboratory of Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland 5 2Department of Chemistry and Biochemistry, University of Bern, 3012 Bern, Switzerland 3Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland †deceased Correspondence to : [email protected] Abstract. High altitude glaciers and ice caps from mid-latitudes and tropical regions contain valuable signals of past climatic 10 and environmental conditions as well as human activities, but for a meaningful interpretation this information needs to be placed in a precise chronological context. For dating the upper part of ice cores from such sites several relatively precise methods exist, but they fail in the older and deeper part, where plastic deformation of the ice results in strong annual layer thinning and a non-linear age-depth relationship. If sufficient organic matter such as plant, wood or insect fragments were found, radiocarbon ( 14 C) analysis had thus been the only option for a direct and absolute dating of deeper ice core sections. 15 However such fragments are rarely found and even then very likely not at the depths and in the resolution desired. About 10 years ago, a new, complementary dating tool was therefore introduced by our group.
    [Show full text]
  • Review of the Stability of Biochar in Soils: Predictability of O:C Molar Ratios
    For reprint orders, please contact [email protected] Review Review of the stability of biochar in soils: predictability of O:C molar ratios Carbon Management (2010) 1(2), 289–303 Kurt A Spokas† Biochar is not a structured homogeneous material; rather it possesses a range of chemical structures and a heterogeneous elemental composition. This variability is based on the conditions of pyrolysis and the biomass parent material, with biochar spanning the range of various forms of black carbon. Thereby, this variability induces a broad spectrum in the observed rates of reactivity and, correspondingly, the overall chemical and microbial stability. From evaluating the current biochar and black carbon degradation studies, there is the suggestion of an overall relationship in biochar stability as a function of the molar ratio of oxygen to carbon (O:C) in the resulting black carbon. In general, a molar ratio of O:C lower than 0.2 appears to provide, at minimum, a 1000-year biochar half-life. The O:C ratio is a function of production temperature, but also accounts for other impacts (e.g., parent material and post-production conditioning/oxidation) that are not captured solely with production temperature. Therefore, the O:C ratio could provide a more robust indicator of biochar stability than production parameters (e.g., pyrolysis temperature and biomass type) or volatile matter determinations. Traditional charcoal production, in a restricted oxy- transferred to a slower cycling form (i.e., black C) that genated environment, has a long history in human has the potential to exist for hundreds to thousands of civilization dating back to the 15th Century, and years [8,9] or possibly longer [10,11].
    [Show full text]
  • On the Deposition Equilibrium of Carbon Nanotubes Or Graphite in the Reforming Processes of Lower Hydrocarbon Fuels
    entropy Article On the Deposition Equilibrium of Carbon Nanotubes or Graphite in the Reforming Processes of Lower Hydrocarbon Fuels Zdzisław Jaworski * and Paulina Pianko-Oprych Faculty of Chemical Technology and Engineering, Institute of Chemical Engineering and Environmental Protection Processes, West Pomeranian University of Technology, Aleja Piastów 42, 71-065 Szczecin, Poland; [email protected] * Correspondence: [email protected]; Tel.: +48-91-449-4020 Received: 9 October 2017; Accepted: 27 November 2017; Published: 30 November 2017 Abstract: The modeling of carbon deposition from C-H-O reformates has usually employed thermodynamic data for graphite, but has rarely employed such data for impure filamentous carbon. Therefore, electrochemical data for the literature on the chemical potential of two types of purified carbon nanotubes (CNTs) are included in the study. Parameter values determining the thermodynamic equilibrium of the deposition of either graphite or CNTs are computed for dry and wet reformates from natural gas and liquefied petroleum gas. The calculation results are presented as the atomic oxygen-to-carbon ratio (O/C) against temperature (200 to 100 ◦C) for various pressures (1 to 30 bar). Areas of O/C for either carbon deposition or deposition-free are computed, and indicate the critical O/C values below which the deposition can occur. Only three types of deposited carbon were found in the studied equilibrium conditions: Graphite, multi-walled CNTs, and single-walled CNTs in bundles. The temperature regions of the appearance of the thermodynamically stable forms of solid carbon are numerically determined as being independent of pressure and the analyzed reactants.
    [Show full text]
  • The Nature of the Deposited Carbon at Methane Cracking Over a Nickel Loaded Wood-Char Chamseddine Guizani, Francisco Javier Escudero Sanz, Sylvain Salvador
    The nature of the deposited carbon at methane cracking over a nickel loaded wood-char Chamseddine Guizani, Francisco Javier Escudero Sanz, Sylvain Salvador To cite this version: Chamseddine Guizani, Francisco Javier Escudero Sanz, Sylvain Salvador. The nature of the deposited carbon at methane cracking over a nickel loaded wood-char. Comptes Rendus Chimie, Elsevier Masson, 2016, 19 (4), pp.423-432. 10.1016/j.crci.2015.10.009. hal-01599996 HAL Id: hal-01599996 https://hal.archives-ouvertes.fr/hal-01599996 Submitted on 4 Apr 2018 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. C. R. Chimie 19 (2016) 423e432 Contents lists available at ScienceDirect Comptes Rendus Chimie www.sciencedirect.com Full paper/Memoire The nature of the deposited carbon at methane cracking over a nickel loaded wood-char La nature du carbone depose a la suite de la reaction de craquage du methane sur un char de biomasse charge en nickel * Chamseddine Guizani , Francisco Javier Escudero Sanz, Sylvain Salvador RAPSODEE, Mines-Albi, route de Teillet 81013 Albi, France article info abstract Article history: The catalytic properties of raw biomass chars and Ni-loaded biomass chars prepared at a Received 19 May 2015 high-heating-rate were assessed in the methane decomposition reaction.
    [Show full text]
  • Pnas11130correction 11223..11223
    Corrections BIOCHEMISTRY NEUROSCIENCE Correction for “Quantitative phosphoproteomic analysis reveals Correction for “GABAA receptor target of tetramethylenedi- system-wide signaling pathways downstream of SDF-1/CXCR4 sulfotetramine,” by Chunqing Zhao, Sung Hee Hwang, Bruce A. in breast cancer stem cells,” by Tingfang Yi, Bo Zhai, Yonghao Buchholz, Timothy S. Carpenter, Felice Lightstone, Jun Yang, Yu, Yoshikawa Kiyotsugu, Thomas Raschle, Manuel Etzkorn, Bruce D. Hammock, and John E. Casida, which appeared in issue Hee-Chan Seo, Michal Nagiec, Rafael E. Luna, Ellis L. Reinherz, 23, June 10, 2014, of Proc Natl Acad Sci USA (111:8607–8612; first John Blenis, Steven P. Gygi, and Gerhard Wagner, which appeared published May 27, 2014; 10.1073/pnas.1407379111). in issue 21, May 27, 2014, of Proc Natl Acad Sci USA (111:E2182– The authors note that the author name Felice Lightstone E2190; first published April 29, 2014; 10.1073/pnas.1404943111). should instead appear as Felice C. Lightstone. The corrected The authors note that all instances of “δ-catenin” should in- author line appears below. The online version has been corrected. stead appear as “p120-catenin.” Chunqing Zhao, Sung Hee Hwang, Bruce A. Buchholz, www.pnas.org/cgi/doi/10.1073/pnas.1411381111 Timothy S. Carpenter, Felice C. Lightstone, Jun Yang, Bruce D. Hammock, and John E. Casida www.pnas.org/cgi/doi/10.1073/pnas.1412593111 GENETICS Correction for “Noninvasive in vivo monitoring of tissue-specific global gene expression in humans,” by Winston Koh, Wenying Pan, Charles Gawad, H. Christina Fan, Geoffrey A. Kerchner, Tony Wyss-Coray, Yair J. Blumenfeld, Yasser Y. El-Sayed, and Stephen R.
    [Show full text]