A General Approach for Kinetic Modeling of Solid-Gas Reactions at Reactor Scale: Application to Kaolinite Dehydroxylation

Favergeon, Loïc; Morandini, Jacques; Pijolat, Michèle; Soustelle, Michel

doi:10.2516/ogst/2012018

Cited by 14 publications

(14 citation statements)

References 28 publications

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“…The infrared spectra are shown in Figure 8. The correspondence between absorption band and surface functional group is shown in Table 2 [14,26]. In the case of 0.5 s, the signal of octahedral O-Al-OH decreased with the rising temperature and disappeared at 1200 • C while the signals of tetrahedral Al-O and meta-kaolinite appeared at 1200 • C. The signal of inner-surface -OH disappeared at 1200 • C while the signal of inner -OH remained at 1200 • C. It is consistent with the dehydroxylation sequence that inner-surface -OH appears first, and then inner -OH.…”

Section: Kaolinite Surface Functional Groups Changementioning

confidence: 99%

“…The activity of Al atoms is the key to adsorption [9,10,40,44]. It could be described as Equation (14) and Figure 15. Raw kaolinite contained is invalid to oxide molecule adsorption.…”

Section: Effect Of Dehydroxylation and Structural Distortion On Metalmentioning

confidence: 99%

“…The thermal behavior of kaolinite has been investigated a lot from the perspective of kaolin processing which mainly uses rotary kiln calcination [11,[13][14][15]. Therefore, the previous results are mostly in the view of soak calcination with the residence time of several hours.…”

Section: Introductionmentioning

confidence: 99%

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Dehydroxylation and Structural Distortion of Kaolinite as a High-Temperature Sorbent in the Furnace

Cheng

Xing

et al. 2019

Minerals

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As a high-temperature sorbent, kaolinite undergoes the flash calcination process in the furnace resulting in the dehydroxylation and structural distortion, which are closely related to its heavy metal/alkali metal adsorption characteristics. We investigated the flash calcination of kaolinite by the experiments using a drop tube furnace and by the characterization of flash-calcined products using thermogravimetric-differential scanning calorimeter (TG-DSC), X-ray diffraction (XRD), Fourier Transform Infrared Spectrometer (FTIR)and nuclear magnetic resonance (NMR). There were three kinds of hydroxyl groups in kaolinite during flash calcination at 800–1300 °C, E-type (~50%, easy), D-type (~40%, difficult) and U-type (~10%, unable) according to the removal difficulty. The hydroxyl groups activation was believed to be the first step of the removal of E-type and D-type hydroxyl groups. The kinetics model of dehydroxylation groups at 900–1200 °C was established following Arrhenius equation with the activation energy of 140 kJ/mol and the pre-exponential factor of 1.32 × 106 s−1. At 800 °C, the removal of E-type hydroxyl groups resulted in the conversion of a part of VI-coordinated Al in kaolinite to V-coordinated Al and the production of meta-kaolinite. When the temperature rose up to 1200 °C, mullite was produced and a part of V-coordinated Al converted to IV-coordinated Al and VI-coordinated Al. Finally, the adsorption characteristics of kaolinite was discussed according to the results of dehydroxylation and structural distortion.

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Section: Kaolinite Surface Functional Groups Changementioning

confidence: 99%

“…The activity of Al atoms is the key to adsorption [9,10,40,44]. It could be described as Equation (14) and Figure 15. Raw kaolinite contained is invalid to oxide molecule adsorption.…”

Section: Effect Of Dehydroxylation and Structural Distortion On Metalmentioning

confidence: 99%

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Dehydroxylation and Structural Distortion of Kaolinite as a High-Temperature Sorbent in the Furnace

Cheng

Xing

et al. 2019

Minerals

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“…In solid-gas reactions, the solid phase is usually a granular medium through which the gaseous reactant circulates and reacts at the solid interface [14]. Due to the reactions occurring at a microscopic level, the solid material undergoes chemical and structural change as the reaction proceeds.…”

Section: Analysis Of Reactionsmentioning

confidence: 99%

“…(9) is determined at every temperature from 25 to 1200°C using Eq. (14), the applied heating rate and the estimated E A . A linear fitting of Eq.…”

Section: The Arrhenius Pre-exponential Factormentioning

confidence: 99%

The effect of the TiC particle size on the preferred oxidation temperature for self-healing of oxide ceramic matrix materials

et al. 2018

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The effect of particle size on the oxidation kinetics of TiC powders is studied. Different sizes of TiC powder ranging from nanometre to submillimetre sizes are investigated. The samples are heated at different heating rates from room temperature up to 1200°C in dry synthetic air. The Kissinger method for analysis of non-isothermal oxidation is used to estimate the activation energy for oxidation of the powders and to identify the active temperature window for efficient self-healing. The master curve plotting method is used to identify the model which best describes the oxidation of TiC powders, and the Senum and Yang method is used to approximate the value for the Arrhenius constant. The oxidation of TiC proceeds via the formation of oxycarbides, anatase and then finally the most stable form: rutile. The activation energy is found to be a strong function of the particle size for particle sizes between 50 nm and 11 lm and becomes constant at larger particle sizes. The data demonstrate how the minimal healing temperature for oxide ceramics containing TiC as healing particles can be tailored between 400 and 1000°C by selecting the right average TiC particle size.

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Linear Driving Force Approximations as Predictive Models for Reactive Sorption

Azzam

Simonetti

2019

Energy Tech

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Herein, the utilization of linear driving‐force approximations as predictive models for hydrogen sulfide removal on a commercial copper‐based sorbent is assessed. Sorption experiments are carried out in a fixed‐bed reactor at different flow conditions, temperatures, total pressures, and inlet hydrogen sulfide concentrations. For large pellet sizes (≥800 μm), quasi‐chemical linear driving‐force approximations, that are first order in both bulk gas‐phase concentration and solid‐phase capacity, effectively model contaminant breakthrough curves. Experimentally determined rate parameters (10.7 ± 0.7 s−1 and 6.5 ± 0.5 s−1 for 800 and 1000 μm‐sized particles, respectively) reflect those determined from pore diffusion within pellets. For small pellet sizes (≤212 μm), linear driving‐force approximations, that are zero order in bulk gas‐phase concentration but first order in solid‐phase capacity, model contaminant breakthrough curves; and rate parameters reflect reaction and diffusion at reactive interfaces rather than bulk or pore diffusion. These studies demonstrate that linear driving‐force approximations can model experimentally determined trace hydrogen sulfide removal parameters. Alternatively, under conditions where bulk and/or pore diffusions are limiting, the rate parameters can be calculated from known engineering theories (e.g., the Chapman–Enskog relation or the Wilke–Chang correlation).

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A General Approach for Kinetic Modeling of Solid-Gas Reactions at Reactor Scale: Application to Kaolinite Dehydroxylation

Cited by 14 publications

References 28 publications

Dehydroxylation and Structural Distortion of Kaolinite as a High-Temperature Sorbent in the Furnace

Dehydroxylation and Structural Distortion of Kaolinite as a High-Temperature Sorbent in the Furnace

The effect of the TiC particle size on the preferred oxidation temperature for self-healing of oxide ceramic matrix materials

Linear Driving Force Approximations as Predictive Models for Reactive Sorption

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