Diffusion kinetics of ethane, ethylene, and their binary mixtures in ethane-selective adsorbents

Gelles, Teresa; Lawson, Shane; Thakkar, Harshul; Rezaei, Fateme

doi:10.1016/j.seppur.2019.115872

Cited by 18 publications

(18 citation statements)

References 58 publications

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“…Blank tests are shown in Figure S1 (Supporting Information). A detailed overview of the ZLC theoretical model can be found in our previous work, and has also been included in the Supplementary Information.…”

Section: Methodsmentioning

confidence: 99%

“…However, utilizing the ZLC method to characterize the diffusion kinetics of CO 2 through amino materials has been widely unexplored. Most recently, our group applied an extended ZLC model to evaluate the effects of surface resistance on ethane and ethylene diffusion through paraffin‐selective MOFs ZIF‐7 and Ni(bdc)(ted) 0.5 . Our findings revealed the presence of strong surface resistance occurring between C─C double bonds of ethylene and the external MOF surface.…”

Section: Introductionmentioning

confidence: 99%

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Diffusion kinetics of CO₂ in amine‐impregnated MIL‐101, alumina, and silica adsorbents

Gelles

Rezaei

2019

AIChE Journal

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CO 2 sorption kinetics of poly(ethylenimine) (PEI)-impregnated MIL-101, γ-alumina, and UVM-7 silica were investigated by the zero-length column technique for the purpose of understanding the effect of amine content, adsorbent porosity, and adsorption temperature on CO 2 sorption rates. Each of the adsorbents was impregnated with three different amine contents (20, 35, and 50 wt%) and the effective diffusion time constants were determined at 25 C. For each respective adsorbent, it was found that increasing the amine content results in diminished diffusion rates. Additionally, it was found that the pore size of the support has a profound effect on diffusional kinetics, where microporous MIL-101 yielded substantially slow desorption rates upon amine-functionalization compared to mesoporous γ-alumina. PEIimpregnated UVM-7 silica was further investigated at 50 and 75 C in order to provide insight into the effect of temperature on sorption kinetics. The results indicated that PEI-impregnated UVM-7 exhibited faster sorption kinetics at higher temperatures. Upon desorption, PEI-UVM-7 silica exhibited two distinct regions of masstransfer control that occur at different sorption times. This is best explained by first the occurrence of surface diffusion followed by diffusion out of the bulky PEI polymer chains. The findings of this study provide novel kinetic characterizations on promising amino-adsorbents for carbon capture applications. K E Y W O R D S γ-alumina, CO 2 capture, diffusion time constant, MIL-101, UVM-7 silica, ZLC technique 1 | INTRODUCTION The rapid rise of anthropogenic CO 2 emissions resulting from fossil fuel combustion has been widely identified as the primary cause to the increase in global temperatures, due to the deleterious effects of this greenhouse gas. 1 Hence, development of cost-effective carbon capture processes is essential for mitigation of CO 2 emissions. 1-4 Aqueous monoethanol amine absorption is regarded as the benchmark technology for post-combustion CO 2 capture, but suffers from high-energy penalties upon solvent regeneration. 3 Alternatively, the direct removal of CO 2 from ambient air has arisen as an attractive option in recent years that could be implemented in residential areas to mitigate emissions resulting from transportation sources. 4,5 Therefore, solid-state adsorbents have been intensively studied as a viable, cost-effective alternative to absorption-based amine scrubbing for practical carbon capture applications. Solid adsorbents, traditionally including zeolites, carbon molecular sieves, activated carbons, activated alumina, and metal-organic frameworks (MOFs), are physical adsorbents and have been extensively studied due to their high efficiency, low regeneration requirements, and long-term stability. 6 However, these adsorbents suffer from inferior capture capacities compared to aqueous amine-scrubbing, as well as reduced working capacities in humidified conditions. 7 Therefore, recent research has focused on the incorporation of amine moieties

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Diffusion kinetics of CO₂ in amine‐impregnated MIL‐101, alumina, and silica adsorbents

Gelles

Rezaei

2019

AIChE Journal

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“…The ZLC method was used for the semi‐quantitative analysis of the diffusion performance. By controlling the testing temperature via recirculation cooling water, the concentration of adsorbate, n‐C8, at the ZLC unit was maintained at a low level (no more than 0.025 bar) 32 to make sure that the measurement was carried out within the linear region of the adsorption isotherm (Henry's law region) as required by the ZLC theory 40 . Before the testing, some verification experiments over Pt/HPMo/SBA‐15‐5 were conducted to ensure that the experimental conditions meet the other theoretical requirements for the ZLC method.…”

Section: Resultsmentioning

confidence: 99%

“…The relative gas concentration ( c / c 0 ) is given by the following equation 32,33 :

\frac{c}{c_{0}} = \sum_{n = 1}^{\infty} \frac{2 L}{β_{n}^{2} + L ((), L + 1)} \exp ((), \frac{- β_{n}^{2} D_{e} t}{R^{2}})

where β n and L are given by the roots of the auxiliary equation:

β_{n} \cot β_{n} + L - 1 = 0

L = \frac{1}{3} \frac{F}{{italicKV}_{S}} \frac{R^{2}}{D_{e}}

where F is the purge flow rate, V s is the sample volume, K is the dimensionless Henry's Law constant, and D e is the effective diffusivity.…”

Section: Methodsmentioning

confidence: 99%

The hydrotreatment of n‐C16 over Pt/HPMo/SBA‐15 and the investigation of diffusion effect using a novel W‐P criterion

Sun

et al. 2021

AIChE Journal

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A series of Pt/HPMo/SBA‐15 catalysts with the pore size as a single variable were prepared to elucidate the internal diffusion effect on the hydrotreatment of n‐C16. A novel model was developed to calculate the Weisz‐Prater number (NW‐P) because the traditional model relies on excessive empirical reference values and affects the accuracy remarkably. The utilization of the internal effectiveness factor, Thiele modulus, and the apparent activities over catalysts with different diffusion capacity gave rise to NW‐P with improved accuracy, which can also be extended to other heterogeneous catalytic systems with macromolecules as reactants. Combining the novel model with the diffusion–reaction kinetic method, a conclusion has been drawn that the formation of m‐i‐C16 is more susceptible to internal diffusion than the consumption of n‐C16. Besides, the pore size should be not less than 10 nm to avoid the step‐limitation of internal diffusion, in the premise of adequate acid sites.

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“…ZIF-7-I (hereinafter ZIF-7) was first obtained by Park et al [29] by solvothermal reaction between zinc nitrate tetrahydrate and benzimidazole in DMF solution. The process proceeded at 130 • C for 48 h. Materials in studies [25,26,[30][31][32][33][34][35] were also synthesized in a similar way. Variations of this technique with varying synthesis times/temperatures was described [36][37][38][39].…”

Section: Introductionmentioning

confidence: 99%

MW Synthesis of ZIF-7. The Effect of Solvent on Particle Size and Hydrogen Sorption Properties

et al. 2020

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We report here fast (15 min) microwave-assisted solvothermal synthesis of zeolitic imidazolate framework material (ZIF-7). We have optimized solvent composition to achieve high porosity and hydrogen capacity and narrow particle size distribution. It was shown that synthesis in N,N-diethylformamide (DEF) results in a layered ZIF-7 III phase, while N,N-dimethylformamide (DMF) as solvent leads to a pure ZIF-7 phase in microwave conditions. A mixture of toluene with DMF allows the production of pure ZIF-7 material only with the triethylamine additive. Obtained materials were comprehensively characterized. We have pointed out that both X-ray diffraction and infrared spectroscopy could be used for the identification of ZIF-7 or ZIF-7 III phases. Although samples obtained in DMF, and in a mixture of DMF, toluene, and triethylamine were assigned to the pure ZIF-7 phase, solvent composition significantly affected the size of particles in the material and nitrogen and hydrogen adsorption process.

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Diffusion kinetics of ethane, ethylene, and their binary mixtures in ethane-selective adsorbents

Cited by 18 publications

References 58 publications

Diffusion kinetics of CO₂ in amine‐impregnated MIL‐101, alumina, and silica adsorbents

Diffusion kinetics of CO₂ in amine‐impregnated MIL‐101, alumina, and silica adsorbents

The hydrotreatment of n‐C16 over Pt/HPMo/SBA‐15 and the investigation of diffusion effect using a novel W‐P criterion

MW Synthesis of ZIF-7. The Effect of Solvent on Particle Size and Hydrogen Sorption Properties

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Diffusion kinetics of ethane, ethylene, and their binary mixtures in ethane-selective adsorbents

Cited by 18 publications

References 58 publications

Diffusion kinetics of CO2 in amine‐impregnated MIL‐101, alumina, and silica adsorbents

Diffusion kinetics of CO2 in amine‐impregnated MIL‐101, alumina, and silica adsorbents

The hydrotreatment of n‐C16 over Pt/HPMo/SBA‐15 and the investigation of diffusion effect using a novel W‐P criterion

MW Synthesis of ZIF-7. The Effect of Solvent on Particle Size and Hydrogen Sorption Properties

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Diffusion kinetics of CO₂ in amine‐impregnated MIL‐101, alumina, and silica adsorbents

Diffusion kinetics of CO₂ in amine‐impregnated MIL‐101, alumina, and silica adsorbents