Rate-Determining Step

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Jaka Sunarso - One of the best experts on this subject based on the ideXlab platform.

  • rate determining Step in sdc ssaf dual phase oxygen permeation membrane
    Journal of Membrane Science, 2019
    Co-Authors: Claudia Li, Wenping Li, Jiuan Jing Chew, Jaka Sunarso
    Abstract:

    Abstract Dense mixed ionic-electronic conducting (MIEC) dual-phase Ce0.85Sm0.15O1.925–Sm0.6Sr0.4Al0.3Fe0.7O3-δ (SDC-SSAF) represents one of the most attractive oxygen-selective membrane materials for oxygen separation from air above 700 °C. Its high phase stability in reducing atmosphere and CO2 resistance allows its potential direct integration into oxyfuel combustion and membrane reactor applications. In this work, the oxygen permeation parameters and properties of SDC-SSAF are evaluated theoretically using the Zhu model, which analyses the role of interfaces in electrochemical oxygen permeation. The model produced good correlation with the experimental data (R2 = 0.9990), with the calculated resistance constants indicating higher resistance encountered at the feed side interface as compared to the permeate side. An analysis of the characteristic thickness indicates increasing influence of surface exchange reactions with decreasing temperature, feed side pressure, and permeate side pressure. Although oxygen permeation is dependent upon various operating conditions, our parametric study reveals that temperature effect surpasses oxygen partial pressure difference effect in enhancing the oxygen permeation flux. Oxygen permeation is limited by surface reactions between 800 and 850 °C and mixed bulk diffusion and surface exchange reactions between 850 and 875 °C. Above 875 °C, the rate determining Step shifts to bulk diffusion.

Claudia Li - One of the best experts on this subject based on the ideXlab platform.

  • rate determining Step in sdc ssaf dual phase oxygen permeation membrane
    Journal of Membrane Science, 2019
    Co-Authors: Claudia Li, Wenping Li, Jiuan Jing Chew, Jaka Sunarso
    Abstract:

    Abstract Dense mixed ionic-electronic conducting (MIEC) dual-phase Ce0.85Sm0.15O1.925–Sm0.6Sr0.4Al0.3Fe0.7O3-δ (SDC-SSAF) represents one of the most attractive oxygen-selective membrane materials for oxygen separation from air above 700 °C. Its high phase stability in reducing atmosphere and CO2 resistance allows its potential direct integration into oxyfuel combustion and membrane reactor applications. In this work, the oxygen permeation parameters and properties of SDC-SSAF are evaluated theoretically using the Zhu model, which analyses the role of interfaces in electrochemical oxygen permeation. The model produced good correlation with the experimental data (R2 = 0.9990), with the calculated resistance constants indicating higher resistance encountered at the feed side interface as compared to the permeate side. An analysis of the characteristic thickness indicates increasing influence of surface exchange reactions with decreasing temperature, feed side pressure, and permeate side pressure. Although oxygen permeation is dependent upon various operating conditions, our parametric study reveals that temperature effect surpasses oxygen partial pressure difference effect in enhancing the oxygen permeation flux. Oxygen permeation is limited by surface reactions between 800 and 850 °C and mixed bulk diffusion and surface exchange reactions between 850 and 875 °C. Above 875 °C, the rate determining Step shifts to bulk diffusion.

Jiuan Jing Chew - One of the best experts on this subject based on the ideXlab platform.

  • rate determining Step in sdc ssaf dual phase oxygen permeation membrane
    Journal of Membrane Science, 2019
    Co-Authors: Claudia Li, Wenping Li, Jiuan Jing Chew, Jaka Sunarso
    Abstract:

    Abstract Dense mixed ionic-electronic conducting (MIEC) dual-phase Ce0.85Sm0.15O1.925–Sm0.6Sr0.4Al0.3Fe0.7O3-δ (SDC-SSAF) represents one of the most attractive oxygen-selective membrane materials for oxygen separation from air above 700 °C. Its high phase stability in reducing atmosphere and CO2 resistance allows its potential direct integration into oxyfuel combustion and membrane reactor applications. In this work, the oxygen permeation parameters and properties of SDC-SSAF are evaluated theoretically using the Zhu model, which analyses the role of interfaces in electrochemical oxygen permeation. The model produced good correlation with the experimental data (R2 = 0.9990), with the calculated resistance constants indicating higher resistance encountered at the feed side interface as compared to the permeate side. An analysis of the characteristic thickness indicates increasing influence of surface exchange reactions with decreasing temperature, feed side pressure, and permeate side pressure. Although oxygen permeation is dependent upon various operating conditions, our parametric study reveals that temperature effect surpasses oxygen partial pressure difference effect in enhancing the oxygen permeation flux. Oxygen permeation is limited by surface reactions between 800 and 850 °C and mixed bulk diffusion and surface exchange reactions between 850 and 875 °C. Above 875 °C, the rate determining Step shifts to bulk diffusion.

Wenping Li - One of the best experts on this subject based on the ideXlab platform.

  • rate determining Step in sdc ssaf dual phase oxygen permeation membrane
    Journal of Membrane Science, 2019
    Co-Authors: Claudia Li, Wenping Li, Jiuan Jing Chew, Jaka Sunarso
    Abstract:

    Abstract Dense mixed ionic-electronic conducting (MIEC) dual-phase Ce0.85Sm0.15O1.925–Sm0.6Sr0.4Al0.3Fe0.7O3-δ (SDC-SSAF) represents one of the most attractive oxygen-selective membrane materials for oxygen separation from air above 700 °C. Its high phase stability in reducing atmosphere and CO2 resistance allows its potential direct integration into oxyfuel combustion and membrane reactor applications. In this work, the oxygen permeation parameters and properties of SDC-SSAF are evaluated theoretically using the Zhu model, which analyses the role of interfaces in electrochemical oxygen permeation. The model produced good correlation with the experimental data (R2 = 0.9990), with the calculated resistance constants indicating higher resistance encountered at the feed side interface as compared to the permeate side. An analysis of the characteristic thickness indicates increasing influence of surface exchange reactions with decreasing temperature, feed side pressure, and permeate side pressure. Although oxygen permeation is dependent upon various operating conditions, our parametric study reveals that temperature effect surpasses oxygen partial pressure difference effect in enhancing the oxygen permeation flux. Oxygen permeation is limited by surface reactions between 800 and 850 °C and mixed bulk diffusion and surface exchange reactions between 850 and 875 °C. Above 875 °C, the rate determining Step shifts to bulk diffusion.

Cristina Iuga - One of the best experts on this subject based on the ideXlab platform.

  • effects of alkyl groups in the rate determining Step of the baeyer villiger reaction of phenyl alkyl ketones a quantum chemistry study
    Journal of Physical Chemistry A, 2012
    Co-Authors: Lino Reyes, Celestino Diazsanchez, Cristina Iuga
    Abstract:

    In this work, we have studied the substituent effect of several alkyl groups in the Rate-Determining Step of the catalyzed Baeyer–Villiger (BV) reaction of phenyl alkyl ketones with performic (PFA) and trifluoroperacetic (TFPAA) acids, using quantum chemistry methods. Our results reveal that the substituent effect is more pronounced in the migration Step barriers than in the corresponding addition Step; that could change the Rate-Determining Step (RDS) of the reaction, as observed in the oxidation of phenyl tert-butyl ketone with both peracids. In addition, the effect of the acid/peracid pairs used is also analyzed. We have demonstrated that the addition Step is less susceptible to the acid/peracid nature since the acid strength and the nucleophilicity of the peracid have opposite effects. The effect of the acid/peracid pair is much more pronounced in the migration Step because it only depends on the leaving ability of the acid, which in turn depends on its strength. These observations are relevant for un...