Thermodynamics of methane adsorption on the microporous carbon adsorbent ACC

Школин, А. В.; Фомкин, А. А.

doi:10.1007/s11172-008-0242-1

Cited by 20 publications

(15 citation statements)

References 9 publications

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“…It should be noted that the obtained dependences almost quantitatively coincide with the data given in the works of Fomkin et al [14,15]; however, in con trast with calculations from [14,15], they do not require additional experimental measurements of the deformation of adsorbent upon adsorption. This is related to the fact that thermodynamic equations (9)-(12) assume the corresponding changes of micropore volume in a 0 (T) and β(T) values.…”

Section: Resultssupporting

confidence: 87%

“…The dependences of activity coefficients from are easily recalculated to the dependences from in accordance with the following relationship: (15) In practical calculations in accordance with the reduced equations, the published reference data on , equilibrium consistent standard states of components in equilibrium phases and , and states of reference for activity coefficients and were used [13].…”

Section: Introductionmentioning

confidence: 99%

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Thermodynamics of methane adsorption on microporous adsorbents at supercritical temperatures

Толмачев

Kryuchenkova

Fomenkov

2014

Prot Met Phys Chem Surf

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Section: Resultssupporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Thermodynamics of methane adsorption on microporous adsorbents at supercritical temperatures

Толмачев

Kryuchenkova

Fomenkov

2014

Prot Met Phys Chem Surf

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“…The differential molar isosteric heat of adsorption, q st , is an important thermodynamic parameter, which describes the heat effects of adsorption processes [ 26 , 27 , 30 , 32 , 33 , 34 ]. By definition [ 30 ], the value of q st is determined as the difference between the molar enthalpy of equilibrium gaseous phase h g and differential molar enthalpy of adsorption system H 1 :

…”

Section: Resultsmentioning

confidence: 99%

“…The applicability of the Bakaev equation was demonstrated by calculating the thermodynamic functions characterizing the adsorption of gases (Xe, Kr, Ar, N 2 , O 2 , H 2 , CH 4 , CO 2 , and He) in microporous adsorbents (zeolites and ACs) in a wide range of temperature and pressure [ 32 , 33 , 34 ]. It should also be noted that an analysis of thermodynamic parameters of an adsorption system, as a function of pressure, temperature, and amounts of adsorbed methane, also provides information on changes in the state of methane molecules in micropores [ 32 ].…”

Section: Introductionmentioning

confidence: 99%

Thermodynamics of Adsorbed Methane Storage Systems Based on Peat-Derived Activated Carbons

et al. 2020

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Two activated carbons (ACs) were prepared from peat using thermochemical K2SO4 activation at 1053–1133 K for 1h, and steam activation at 1173K for 30 (AC-4) and 45 (AC-6) min. The steam activation duration affected the microporous structure and chemical composition of ACs, which are crucial for their adsorption performance in the methane storage technique. AC-6 displays a higher micropore volume (0.60 cm3/g), specific BET surface (1334 m2/g), and a lower fraction of mesopores calculated from the benzene vapor adsorption/desorption isotherms at 293K. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and small-angle X-ray scattering (SAXS) investigations of ACs revealed their heterogeneous morphology and chemical composition determined by the precursor and activation conditions. A thermodynamic analysis of methane adsorption at pressures up to 25 MPa and temperatures from 178 to 360K extended to impacts of the nonideality of a gaseous phase and non-inertness of an adsorbent made it possible to evaluate the heat effects and thermodynamic state functions in the methane-AC adsorption systems. At 270 K and methane adsorption value of ~8 mmol/g, the isosteric heat capacity of the methane-AC-4 system exceeded by ~45% that evaluated for the methane-AC-6 system. The higher micropore volume and structural heterogeneity of the more activated AC-6 compared to AC-4 determine its superior methane adsorption performance.

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“…The adsorbate enthalpy is complicated to determine because it, in turn, depends on the heat of adsorption. The thermodynamic approach of Bakaev [11,12] is the most interesting of several approaches for determining the heat of adsorption. It allows the actual properties of methane and the adsorbent deformation to be considered.…”

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confidence: 99%

Capacity and Thermodynamic Nomograph for an Adsorption Methane Storage System

et al. 2016

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General equations for calculation of the capacity and thermodynamic properties of adsorption methane storage systems were written. Experimental results for methane adsorption on AU-1 adsorbent were analyzed and plotted in the nomograph of capacity and thermodynamic properties of the adsorbentadsorbate-gas adsorption system. Methods for graphical calculation of the processes occurring in the system were presented.Adsorption storage systems for natural gas (methane) are very promising not only for storage but also for transportation. An adsorption storage system comprises a container fi lled with a microporous adsorbent. A gas volume of 150-193 m 3 per m 3 of the best carbon adsorbents, e.g., carbon fi ber [1] and active carbons [2], and, according to calculations, 230-284 m 3 per m 3 of metal-organic adsorbents [3], is achieved at pressures of 3.5-7.0 MPa. This is comparable to the corresponding values for compressed natural gas at 20 MPa. Industrial adsorbents (active carbons and zeolites) were developed for different problems so that their capacity is usually lower at 90-110 m 3 /m 3 at 3.5 MPa and 20-25°C.Adsorption storage systems are considered to be safer than traditional compressed and liquid storage systems because the stored gas is bound, which prevents detonation within a tank and rapid loss of gas through a breach. Highly hazardous acetylene is commonly stored in active-carbon adsorption storage systems [4]. An adsorption storage system can conserve energy because of the lower loading pressure and other features.The high heat of adsorption of methane is the principal drawback of natural-gas adsorption storage systems. Considering the signifi cant amount of stored gas, the temperature changes considerably during adsorption and desorption. The adsorbent temperature during loading increases by 30-60 K [5] although the adsorbent dynamic capacity decreases as a result [6]. The reverse effects arise during desorption, i.e., the temperature decreases whereas the adsorption capacity and the amount of residual gas in the empty tank increase. The heat of desorption has a smaller negative effect because of the low residual gas pressures [7].Methods for dissipating heat of adsorption (during loading) or adding heat (during gas release) were developed because the thermal effects were signifi cant. They usually involved placing a heat exchanger within the adsorbent or purging with natural gas.The majority of the research was either experimental or simulated by computer. Both approaches were expensive or labor-intensive and poorly suited for practical calculations of the many processes occurring in adsorption storage systems. Graphs of the properties of various compounds are convenient to use in practice to calculate the processes occurring in them.

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Thermodynamics of methane adsorption on the microporous carbon adsorbent ACC

Cited by 20 publications

References 9 publications

Thermodynamics of methane adsorption on microporous adsorbents at supercritical temperatures

Thermodynamics of methane adsorption on microporous adsorbents at supercritical temperatures

Thermodynamics of Adsorbed Methane Storage Systems Based on Peat-Derived Activated Carbons

Capacity and Thermodynamic Nomograph for an Adsorption Methane Storage System

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