Effects of pore structure of granular activated carbons on CH4 enrichment from CH4/N2 by vacuum pressure swing adsorption

Gu, Min; Zhang, Bo; Qi, Zhendong; Liu, Zhenjian; Duan, Shuo; Du, Xidong; Xian, Xuefu

doi:10.1016/j.seppur.2015.03.051

Cited by 67 publications

(52 citation statements)

References 22 publications

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“…One particular source of methane gas is coal mine gas, also referred to coal‐bed gas, which is a less conventional natural gas that is stored in coal seams and generally consists of CH 4 and N 2 , in addition to small amounts of CO 2 , O 2 , H 2 O, and other gases 4 . During the coal mining process, these coal‐bed gases are usually released, and in the most cases, the released coal‐bed gases contain low concentrations of CH 4 within the mixture (typically <30%) 5 . It is difficult to directly utilize these gas streams as a result of the low concentrations of methane, and furthermore, direct discharge of coal‐bed gases to the atmosphere would potentially have a destructive effect on climate change due to the 20‐fold greater greenhouse gas effect of methane relative to that of carbon dioxide, as well as the large number of coal mine gas resources around the world 6 .…”

Section: Introductionmentioning

confidence: 99%

Facile synthesis of ultramicroporous carbon adsorbents with ultra‐high CH₄ uptake by in situ ionic activation

Wang

et al. 2020

AIChE Journal

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We introduce a straightforward method for the preparation of novel starch‐based ultramicroporous carbons (SCs) that demonstrate high CH4 uptake and excellent CH4/N2 selectivity. These SCs are derived from a combination of starch and 1–6 wt.% of acrylic acid, and the resulting materials are amenable to surface cation exchangeability as demonstrated by the formation of highly dispersed K+ in carbon precursors. Following activation, these SCs contain ultramicropores with narrow pore‐size distributions of <0.7 nm, leading to porous carbon‐rich materials that exhibit CH4 uptake values as high as 1.86 mmol/g at 100 kPa and 298 K, the highest uptake value for CH4 to date, with the IAST‐predicted CH4/N2 selectivity up to 5.7. Both the potential mechanism for the formation of the narrow pores and the origin of the favorable CH4 adsorption properties are discussed and examined. This work may potentially guide future designs for carbon‐rich materials with excellent gas adsorption properties.

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Section: Introductionmentioning

confidence: 99%

Facile synthesis of ultramicroporous carbon adsorbents with ultra‐high CH₄ uptake by in situ ionic activation

Wang

et al. 2020

AIChE Journal

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“…In order to improve the CH 4 /N 2 adsorption selectivity and maintain the adsorption capacity of CH 4 , the relationship between CH 4 and N 2 adsorption properties and the pore texture were studied in detail. ZAC(32) possesses a lower V mic and a larger S ext than ZAC (24), and the adsorption capacity and selectivity of CH 4 and N 2 showed the lower values on ZAC (32), indicating that the high adsorption capacity and selectivity of CH 4 and N 2 results from the large micropore volume rather than S ext [40][41][42][43][44][45]. In Figure 6, the adsorption capacity of CH 4 and N 2 and adsorption selectivity α CH 4 /N 2 are plotted versus V mic .…”

Section: Effect Of Pore Structure and Surface Properties On Thementioning

confidence: 99%

CH₄/N₂ Adsorptive Separation on Zeolite X/AC Composites

Xue

Cheng

Hao

et al. 2019

Journal of Chemistry

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A series of zeolite X/activated carbon (AC) composites were prepared from the same starting materials at various activation time. The corresponding modified samples were obtained by being treated with diluted NH4Cl solution. The relationship between porosity development, surface properties, and CH4/N2 adsorption performance was investigated. The increase of micropore volume is beneficial to the improvement of CH4 and N2 adsorption capacity, but more sensitive for CH4. In addition, the polar functional groups of zeolite X/AC composites may enhance CH4 adsorption capacity. More importantly, both developing micropore structure and surface modification contributed to enhance the adsorption selectivity αCH4/N2. As the optimum sample of these studies, HZAC(24) showed CH4 adsorption capacity of 17.3 cm3/g and the highest adsorption selectivity αCH4/N2 of 3.4. The CH4 and N2 adsorption isotherms of all samples can be well fitted by the Langmuir–Freundlich model. HZAC(24) showed an excellent cyclability of adsorption/desorption of CH4 with a neglectable capacity loss after subsequent cycles. Moreover, HZAC(24) displayed relatively rapid adsorption kinetics. These properties of zeolite X/AC composites are essential for the adsorptive separation of CH4 from N2 in the pressure swing adsorption (PSA) process.

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“…Zhang et al 16 used PSA to separate 27%/73% CH 4 /N 2 , and CH 4 was purified to 57.2%, with methane recovery of around 91%. Vacuum pressure swing adsorption (VPSA) with activated carbon was used by Gu et al 17 to separate binary mixtures of 30%/70% CH 4 /N 2 , and a CH 4 enrichment of 66.6% was achieved. However, O 2 was neglected in the above studies.…”

Section: Introductionmentioning

confidence: 99%

Enrichment of Oxygen-Containing Low-Concentration Coalbed Methane with CMS-3KT as the Adsorbent

et al. 2021

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A type of carbon molecular sieve (CMS-3KT) was used as the adsorbent for the CH 4 enrichment of a methane/oxygen/nitrogen (CH 4 /O 2 /N 2 ) mixture using micro-positive pressure vacuum pressure swing adsorption (∼120 kPa). The adsorption isotherms of individual CH 4 , O 2 , and N 2 on CMS-3KT were studied and fitted. The results indicated the important influence of the adsorbent surface heterogeneity on the adsorption equilibrium process. In addition, the interaction of adsorbent–adsorbate in this process was studied from the measured adsorption heat. The adsorption uptake curves were fitted linearly with a classical micropore model for evaluating the kinetics-based separation possibility of CH 4 /O 2 /N 2 , and the corresponding diffusion time constants of CH 4 , O 2 , and N 2 were calculated. Based on the results of adsorption equilibrium and kinetics, breakthrough experiments were employed to explore the upper limit value of methane concentration in feed gas such that methane can be enriched feasibly but difficultly. The breakthrough experiments were performed on the CH 4 /O 2 /N 2 mixture with CH 4 concentration ranging from 1 to 30%. Regarding industrial application, the O 2 removal and CH 4 enrichment performance of ultra-low-concentration methane (CH 4 < 5%) were evaluated according to the results of the breakthrough experiment. The results indicated that the proposed method was promising for enriching O 2 -containing ultra-low-concentration CBM.

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Effects of pore structure of granular activated carbons on CH4 enrichment from CH4/N2 by vacuum pressure swing adsorption

Cited by 67 publications

References 22 publications

Facile synthesis of ultramicroporous carbon adsorbents with ultra‐high CH₄ uptake by in situ ionic activation

Facile synthesis of ultramicroporous carbon adsorbents with ultra‐high CH₄ uptake by in situ ionic activation

CH₄/N₂ Adsorptive Separation on Zeolite X/AC Composites

Enrichment of Oxygen-Containing Low-Concentration Coalbed Methane with CMS-3KT as the Adsorbent

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Effects of pore structure of granular activated carbons on CH4 enrichment from CH4/N2 by vacuum pressure swing adsorption

Cited by 67 publications

References 22 publications

Facile synthesis of ultramicroporous carbon adsorbents with ultra‐high CH4 uptake by in situ ionic activation

Facile synthesis of ultramicroporous carbon adsorbents with ultra‐high CH4 uptake by in situ ionic activation

CH4/N2 Adsorptive Separation on Zeolite X/AC Composites

Enrichment of Oxygen-Containing Low-Concentration Coalbed Methane with CMS-3KT as the Adsorbent

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Facile synthesis of ultramicroporous carbon adsorbents with ultra‐high CH₄ uptake by in situ ionic activation

Facile synthesis of ultramicroporous carbon adsorbents with ultra‐high CH₄ uptake by in situ ionic activation

CH₄/N₂ Adsorptive Separation on Zeolite X/AC Composites