ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

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

Proceed reservation?

Export
  • 11
    Electronic Resource
    Electronic Resource
    Transport of aromatic molecules in NaY Zeolite powders (1990)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 36 (1990), S. 1562-1568 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Xenon-129 NMR is used to probe macroscopic distributions of aromatic molecules adsorbed in a packed bed of 1-μm NaY zeolite particles. Relative rates of guest transport through the intracrystalline (micro) and intercrystalline (macro) pores play a unique role in the axial distribution of sorbate molecules, such as hexamethylbenzene, in a zeolite powder. Xenon-129 NMR spectra show that a sharp HMB adsorption front advances through a bed of dehydrated NaY crystallites at 523 K. However, at 573 K or in the presence of coadsorbed water, HMB species disperse through the bed without forming a sharp boundary between adsorption zones.When guest transport is controlled by pseudosteady-state diffusion in the macropores, axial penetration of the bed by vapor-phase guest species occurs in a sharp adsorption front. A shrinking-core transport model then quantitatively estimates the intracrystalline diffusivities of HMB in dehydrated and partially hydrated NaY zeolite of 10-11 and 10-13 m2/s, respectively, at 523 K. Xenon-129 NMR proves to be a powerful tool for probing adsorbed guest distribution in zeolites, allowing relative time scales to be established for transport of molecular guests in NaY powders.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690361012
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 12
    Electronic Resource
    Electronic Resource
    Simulation of a multiple substrate reactor for chemical vapor infiltration of pyrolytic carbon within carbon-carbon composites (1993)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 39 (1993), S. 1196-1209 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A model for a pilot-scale chemical vapor infiltration (CVI) reactor in which multiple substrates are densified simultaneously by carbon deposition from a pyrolyzing hydrocarbon is presented. Kinetic expressions and parameters and transport properties for carbon deposition from propylene determined from experimental studies and a single substrate CVI model are incorporated into the pilot reactor model. The two-dimensional transport equations for heat, mass and momentum transfer are solved for the entire reactor to simulate the effects of varied operating conditions on substrate densification throughout the reactor during the CVI process. Of the conditions simulated, the reactor temperature was found to have the most significant impact on both the uniformity of densification and the process time required. As the temperature increased, the uniformity of densification decreased and the time at which pore blockage at the outer surface occurred was shortened. Increasing the hydrocarbon feed concentration shortened the process time, but did not affect the final level of densification, while the feed rate only affected CVI at intermediate times. Comparison between experimental pilot reactor results and model predictions were satisfactory at short and long times, but agreement was less satisfactory at intermediate times.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690390711
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 13
    Electronic Resource
    Electronic Resource
    Effect of temperature on the phase equilibrium of aqueous two-phase polymer systems (1993)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 39 (1993), S. 1976-1984 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We report experimental data showing the effect of temperature on polymer partitioning in the dextran (DEX500)-polyethylene glycol (PEG8000)-water system. Increasing temperature increases the concentration of PEG in the top phase and decreases the concentration of DEX in the bottom phase. A solution thermodynamic model based on local compositions with temperature-dependent parameters correlates the experimental data well, and an efficient Gibbs-free energy minimization algorithm for phase equilibrium calculations is described. The partial molar enthalpies and entropies of each of the solutes, calculated with the model, are negative and decrease in magnitude as temperature increases.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690391208
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 14
    Electronic Resource
    Electronic Resource
    Permeation studies on oriented single-crystal ferrierite membranes (1997)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 43 (1997), S. 83-90 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Large, high-quality, single crystals of pure-silica ferrierite are synthesized, and the structure is described. Selected individual crystals (approximately 600 μm X 500 μm X 20 μm) are mounted in a membrane configuration so that only the 10-membered-ring channels (5.4 Å X 5.4 Å X 4.2 Å) or the 8-membered-ring channels (4.6 Å X 3.7 Å X 3.0 Å) are accessible for gas-molecule permeation. The first examples of transport exclusively through 8- or 10-membered-ring channel systems are reported and obtained through crystal orientation in the membrane. A series. of adsorption experiments are conducted to help select suitable probe molecules and evaluate the role of adsorption in the permeation process for single-crystal membranes. Methane, n-butane, isobutane and nitrogen probe molecules are used to study intracrystalline sorption and transport effects for different crystal orientations, pressures and temperatures. Both pure-gas selectivities and mixed-gas separation factors are reported. A mixed-gas separation factor of n-butane/isobutane = 116 for the 10-membered-ring orientation of the crystal at 383 K and a transmembrane pressure difference of 1.01 X 105 Pa are found using this technique. In addition, molecular sieving is observed for the 8-membered-ring orientation of the crystal since methane, but not butane, transport is observed for this crystal orientation.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690430111
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 15
    Electronic Resource
    Electronic Resource
    Oxygen transport in biofilm electrodes for screening of toxic chemicals (1990)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 36 (1990), S. 19-28 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A biosensor electrode system with unique configuration and a thin layer of immobilized yeast cells, set on the surface of an amperometric oxygen membrane electrode, was developed for rapid screening of toxic chemicals in a variety of pollution and process control applications. Measurement is based on the instantaneous detection of changes in oxygen respiratory activity of biofilm of yeast cells upon exposure to toxic chemicals.The design of this electrode system, referred to as biofilm electrodes, was based on a mathematical model of oxygen transport in the biofilm and the electrochemical current response. The biofilm, which consists of three sublayers - boundary layer, filter pad, and yeast cell layer - was modeled as a one composite diffusion layer, or three separate layers in series. While the three layer model is more theoretically complete, the one layer model was more reliable and simpler to use.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690360105
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 16
    Electronic Resource
    Electronic Resource
    Stirring characteristics in bioreactors (1990)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 36 (1990), S. 1361-1369 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Distribution data of local values of specific kinetic energy of medium flow in the bioreactor volume made it possible to determine some integral criteria. The relationship of these criteria, microorganism growth and biosynthesis characteristics was studied in 5-5,000-L bioreactors. Energy-efficient stirring systems that ensure a minimum damage of cells have been also studied.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690360909
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 17
    Electronic Resource
    Electronic Resource
    Static liquid holdup in packed beds of spherical particles (1991)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1733-1736 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690371117
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 18
    Electronic Resource
    Electronic Resource
    Detailed chemical kinetics model for supercritical water oxidation of C1 compounds and H2 (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1874-1888 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A detailed chemical kinetics model comprising 148 reversible elementory reactions for the supercritical water oxidation (SCWO) of methane, methanol, carbon monoxide and hydrogen was developed. Rate constants were taken from previous critical evaluations. The Lindemann model, at times modified with a broadening parameter, was used to account for the effects of pressure on the kinetics of unimolecular reactions. Model predictions were compared with published experimental SCWO kinetics data for 450-650°C and 240-250 atm. The model correctly predicted global reaction orders for all four fuels to within their uncertainties. In addition, the model correctly predicted that the global reaction orders for O2 during methanol and hydrogen oxidation were essentially zero, and that the O2 concentration had the greatest effect on the methane oxidation rate. The pseudo-first-order rate constants predicted by the model were consistently higher than the experimental values, but the global activation energies were predicted correctly for methane oxidation and for CO and H2 oxidation at high temperatures. The model's predictions generally became worse as the temperature decreased toward the critical point of water. A sensitivity analysis revealed that fewer than 20 elementaty reactions largely controlled the oxidation kinetics for the compounds studied. Nearly half of these reactions involved HO2, which is an important free radical for SCWO. Quantitative agreement with the experimental methane conversions was obtained by adjusting the preexponential factors for three elementary reactions within their uncertainties. It could also be obtained by using the JANAF value (0.5 kcal/mol) for the standard heat of formation of HO2, but this value is lower than other recently recommended values.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690410806
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 19
    Electronic Resource
    Electronic Resource
    Molecular thermodynamic properties of protein solutions from partial specific volumes (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1005-1009 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Partial specific volumes at 25°C are reported for α-chymotrypsinogen in aqueous solutions containing NaCl, citrate, and/or polyethylene gycol (PEG) over a range of protein concentrations. The concentration dependence of the partial specific volume can be either positive or negative, depending on the solvent. For example, the partial specific volume increases with increasing protein concentration in NaCl/citrate solutions at high salt concentrations, and decreases with increasing protein concentration in solutions containing PEG. Kirkwood-Buff solution theory has been applied to interpret these results, and it was found that the concentration dependence is determined by two factors: (1) the effective or solvent-averaged interactions between protein molecules in solution, and (2) three-body protein - protein - solvent and protein - solvent - solvent interactions. An approach is proposed for the experimental determination of both contributions that involves measuring osmotic pressures and volumetric properties of dilute to concentrated protein solutions.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690410431
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 20
    Electronic Resource
    Electronic Resource
    Reactions at supercritical conditions: Applications and fundamentals (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1723-1778 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Supercritical fluids posses properties that make them attractive as media for chemical reactions. Conducting chemical reactions at supercritical conditions affords opportunities to manipulate the reaction environment (solvent properties) by manipulating pressure, to enhance the solubilities of reactants and products, to eliminate interphase transport limitations on reaction rates, and to integrate reaction and separation unit operations. Supercritical conditions may be advantageous for reactions involved in fuels processing, biomass conversion, biocatalysis, homogeneous and heterogeneous catalysis, environmental control, polymerization, materials synthesis, and chemical synthesis. Moreover, supercritical fluids can be used profitably in fundamental chemical investigations of intermolecular interactions and their influence on chemical processes. Work on chemical reactions in and with supercritical fluids is reviewed. We discuss both fundamental studies and applications of reactions at supercritical conditions, with focus on work published after 1985.
    Additional Material: 43 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690410712
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...