Kooperativer Bibliotheksverbund

Berlin Brandenburg

and
and

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Language
Year
  • 1
    Language: English
    In: The journal of physical chemistry. A, 18 June 2015, Vol.119(24), pp.6475-82
    Description: The radical concentrations and g factors of stable organic radicals in different lignin preparations were determined by X-band EPR at 9 GHz. We observed that the g factors of these radicals are largely determined by the extraction process and not by the botanical origin of the lignin. The parameter mostly influencing the g factor is the pH value during lignin extraction. This effect was studied in depth using high-field EPR spectroscopy at 263 GHz. We were able to determine the gxx, gyy, and gzz components of the g tensor of the stable organic radicals in lignin. With the enhanced resolution of high-field EPR, distinct radical species could be found in this complex polymer. The radical species are assigned to substituted o-semiquinone radicals and can exist in different protonation states SH3+, SH2, SH1-, and S2-. The proposed model structures are supported by DFT calculations. The g principal values of the proposed structure were all in reasonable agreement with the experiments.
    Keywords: Electron Spin Resonance Spectroscopy -- Methods ; Lignin -- Chemistry
    ISSN: 10895639
    E-ISSN: 1520-5215
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Language: English
    In: Industrial & Engineering Chemistry Research, 04/26/2017, Vol.56(16), pp.4847-4855
    Description: Diffusion coefficients of various solutes in supercritical water, which were either measured or retrieved from Molecular Dynamics simulations, were reviewed. Diffusion coefficients of molecules relevant for supercritical water processes were calculated with correlations reported in the literature and compared to the values of reference data. For conditions well above the critical point of water, the simple Stokes-Einstein equation predicts the diffusion coefficients with an accuracy better than 20%. For conditions near the critical point, the Wilke-Chang correlation gives the most accurate results. Diffusion coefficients for typical molecules occurring in supercritical water processes such as O2, N2, CO, CO2, or CH4 are estimated to be in the range of 60 × 10-9 m2/s at 673 K and 30 MPa. For H2, for which no experimental data are available, much higher diffusion coefficients in the range of 250 × 10-9 m2/s seem plausible. The data set of binary diffusion coefficients in supercritical water, either determined experimentally or by Molecular Dynamics simulations, should be extended significantly to include more solutes, as well as higher temperatures and pressures.
    Keywords: Diffusion-Coefficient ; Supercritical-Water ; MD-Simulation ; Experimental-Data ; Critical-Point ; Diffusionskoeffizient ; Superkritisches Wasser ; Molekulardynamische Simulation ; Experimentelle Daten ; Kritischer Punkt ; Engineering;
    ISSN: 0888-5885
    E-ISSN: 1520-5045
    Source: American Chemical Society (via CrossRef)
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Language: English
    In: Industrial & engineering chemistry research, 23 November 2016, Vol.55(46), pp.11910-11922
    Description: Hydrothermal oxidation (HTO) provides an efficient technique to completely destroy wet organic wastes. In this study, HTO was applied to treat fecal sludge at well-defined experimental conditions. Four different kinetic models were adjusted to the obtained data. Among others, a distributed activation energy model (DAEM) was applied. A total of 33 experiments were carried out in an unstirred batch reactor with pressurized air as the oxidant at temperatures of 〈470 °C, oxygen-to-fuel equivalence ratios between 0 and 1.9, feed concentrations between 3.9 and 9.8 mol L (TOC = total organic carbon), and reaction times between 86 and 1572 s. Decomposition of the fecal sludge was monitored by means of the conversion of TOC to CO and CO. In the presence of oxygen, ignition of the reaction was observed around 300 °C, followed by further rapid decomposition of the organic material. The TOC was completely decomposed to CO within 25 min at 470 °C and an oxygen-to-fuel equivalence ratio of 1.2. CO was formed as an intermediate product, and no other combustible products were found in the gas. At certain reaction conditions, the formation of unwanted coke and tarlike products occurred. The reaction temperature and oxygen-to-fuel equivalence ratio showed a significant influence on TOC conversion, while the initial TOC concentration did not. Conversion of TOC to CO could be well described with a first-order rate law and an activation energy of 39 kJ mol.
    Keywords: Article;
    ISSN: 0888-5885
    E-ISSN: 15205045
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Language: English
    In: Catalysis Today, March 15, 2014, Vol.223, p.35(9)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.cattod.2013.12.001 Byline: Mariluz Bagnoud-Velasquez, Martin Brandenberger, Frederic Vogel, Christian Ludwig Abstract: Author Affiliation: (a) Swiss Federal Institute of Technology Lausanne, ENAC-IIE, 1015 Lausanne, Switzerland (b) Paul Scherrer Institute (PSI), General Energy Research Department, Laboratory for Bioenergy and Catalysis, CH-5232 Villigen PSI, Switzerland Article History: Received 23 February 2013; Revised 24 November 2013; Accepted 4 December 2013
    Keywords: Recycling -- Case Studies
    ISSN: 0920-5861
    Source: Cengage Learning, Inc.
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Language: English
    In: Catalysis Today, March 15, 2014, Vol.223, p.35(9)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.cattod.2013.12.001 Byline: Mariluz Bagnoud-Velasquez, Martin Brandenberger, Frederic Vogel, Christian Ludwig Abstract: Author Affiliation: (a) Ecole Polytechnique Federale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC-IIE), 1015 Lausanne, Switzerland (b) Paul Scherrer Institute (PSI), General Energy Research Department (ENE-LBK), CH-5232 Villigen PSI, Switzerland (c) University of Applied Sciences and Arts Northwestern Switzerland (FHNW), Klosterzelgstrasse 2, 5210 Windisch, Switzerland Article History: Received 23 February 2013; Revised 24 November 2013; Accepted 4 December 2013
    Keywords: Recycling -- Case Studies
    ISSN: 0920-5861
    Source: Cengage Learning, Inc.
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Language: English
    In: Journal of Catalysis, May, 2013, Vol.301, p.38(8)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jcat.2013.01.018 Byline: Marian Dreher (a), Benjamin Johnson (b), Andrew A. Peterson (b), Maarten Nachtegaal (a), Jorg Wambach (a), Frederic Vogel (a) Keywords: SCWG; Supercritical water gasification; Supported metal catalyst; Ruthenium; Poisoning; Methanation; In situ; EXAFS; DFT; Isotope labeling Abstract: The mechanisms of the methanation reaction and sulfur poisoning of Ru/C were studied via operando EXAFS in supercritical water, combined with isotope labeling and DFT calculations. The results show that the Ru surface is only partially covered by sulfur under these conditions, leading to a change in the abundance of CH.sub.x surface adsorbates and thus to a change in catalyst reactivity and selectivity. Display Omitted Author Affiliation: (a) Paul Scherrer Institut, 5232 Villigen PSI, Switzerland (b) Brown University, School of Engineering, 02912 Providence RI, USA Article History: Received 23 October 2012; Revised 21 January 2013; Accepted 25 January 2013
    Keywords: Sulfur Compounds ; Platinum Group Compounds ; Sulfur ; Ruthenium ; Catalysis
    ISSN: 0021-9517
    Source: Cengage Learning, Inc.
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Language: English
    In: Angewandte Chemie International Edition, 12 March 2012, Vol.51(11), pp.2533-2533
    Keywords: Ethanol ; Reforming ; Ruthenium ; Supercritical Fluids ; X‐Ray Absorption Spectroscopy
    ISSN: 1433-7851
    E-ISSN: 1521-3773
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Language: English
    In: Industrial & Engineering Chemistry Research, 05/31/2017, Vol.56(21), pp.6256-6265
    Description: Continuous catalytic supercritical water gasification (CSCWG; 400 °C, 28 MPa) of microalgal biomass (Chlorella vulgaris) was carried out at the microalgae production site of ZHAW in Wädenswil (Switzerland) nonstop over a period of 100 h. Microalgae slurries (3-15 wt%) were successfully gasified to a methane-rich gas for 55 h. The low total organic carbon of the reactor effluent (〈400 mg L-1) recorded during that period demonstrated the high catalytic activity of the Ru/C catalyst for converting microalgae to the gaseous products. The addition of a sulfur removal step with a commercial zinc oxide adsorbent was essential for protecting the catalyst against sulfur poisoning. A brine effluent rich in nutrients (N, K, S, P, Na) was withdrawn continuously from a salt separator. In summary, the use of a zinc oxide adsorbent upstream of the catalyst bed, together with a higher ruthenium loading of the catalyst, improved the long-term performance of the CSCWG process significantly.
    Keywords: Supercritical-Water ; Effluent ; Zinc-Oxide ; Adsorbent ; Sulfur ; Desulfurisation ; Biomass ; Toc:Total-Organic-Carbon ; Ruthenium ; Microalgae ; Catalyst-Activity ; Intoxication ; Reactors ; Chlorella-Vulgaris ; Switzerland ; Superkritisches Wasser ; Abwasser ; Zinkoxid ; Adsorptionsmittel ; Schwefel ; Schwefelentzug ; Biomasse ; Gesamter Organischer Kohlenstoff ; Ruthenium ; Mikroalge ; Katalytische Aktivität ; Vergiftung ; Reaktor ; Chlorella Vulgaris ; Schweiz ; Engineering;
    ISSN: 0888-5885
    E-ISSN: 1520-5045
    Source: American Chemical Society (via CrossRef)
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Language: English
    In: Industrial & Engineering Chemistry Research, 05/21/2014, Vol.53(20), pp.8404-8415
    Description: We have developed a continuous process for the catalytic hydrothermal gasification of wet biomass to synthetic natural gas (SNG). Salts contained in the biomass and released during the liquefaction step are continuously withdrawn in the supercritical salt separation step upstream of the catalytic reactor. The catalytic reactor is operated at temperatures of 400-450 degree C and pressures of 25-35 MPa. In this article we provide a detailed description of the process and demonstrate the proof of concept as well as the process operation characteristics, based on a systematic study of the continuous gasification of aqueous solutions of glycerol with and without K sub(3)PO sub(4) with simultaneous salt recovery. Glycerol was gasified efficiently to a methane-rich gas without the formation of tars or char. The gas composition corresponded to the thermodynamic equilibrium. The process could be operated in an autothermal mode, although the large surface-to-volume ratio and the imperfect insulation of the laboratory-scale reactor were responsible for appreciable heat losses along the catalytic fixed-bed. The presence of potassium phosphate, not completely removed upstream of the reactor, led to a shift in the gas composition toward C sub(2)-C sub(4) hydrocarbons. However, this effect on the catalyst was reversible.
    Keywords: Gas Composition ; Reactors ; Recovery ; Glycerols ; Gasification ; Upstream ; Catalysts ; Biomass ; Catalysis ; Analysis (MD) ; Chemical Analysis (Ep) ; Chemical Analysis (Ed) ; Chemical Analysis (EC);
    ISSN: 0888-5885
    E-ISSN: 1520-5045
    Source: American Chemical Society (via CrossRef)
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Language: English
    In: Energy & Fuels, 08/15/2013, Vol.27(8), pp.4739-4747
    Description: Eleven commercial stabilized and unstabilized zirconia and titania samples have been tested for stability as potential catalyst supports for supercritical water gasification at 400 degree C and 28.5 MPa. Samples based on monoclinic...
    Keywords: Zirconium Dioxide ; Titanium Dioxide ; Tetragonal Zirconia ; Surface Area ; Ruthenium ; Catalysts ; Stability ; Catalysis ; Fuels and Propellants (Mt) ; General and Nonclassified (MD) ; General and Nonclassified (Ep) ; General and Nonclassified (Ed) ; General and Nonclassified (EC) ; Power Systems (General) (Ea) ; Energy Production and Conversion (Ah);
    ISSN: 0887-0624
    E-ISSN: 1520-5029
    Source: American Chemical Society (via CrossRef)
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. Further information can be found on the KOBV privacy pages