Microporous Carbon Adsorbent Research Articles

Preparation of Microporous Carbon Adsorbents from the Birch Bark

Preparation of Microporous Carbon Adsorbents from the Birch Bark

Deformation of AUK microporous carbon adsorbent induced by xenon adsorption

Deformation of AUK microporous carbon adsorbent induced by xenon adsorption

Polyfuran-Derived Microporous Carbons for Enhanced Adsorption of CO₂ and CH₄.

Oxygen-doped microporous carbons were synthesized by chemical activation of polyfuran with KOH or ZnCl2 at 600 and 800 °C. It was found that KOH preserves and ZnCl2 eliminates the O-C functional groups in the activation process. The O-doped carbon activated with KOH at 800 °C exhibited a high CO2 capacity (4.96 mmol g(-1), 273 K, 1 bar) and CH4 adsorption capacity (2.27 mmol g(-1), 273 K, 1 bar). At 298 K and 1 bar, a very high selectivity for separating CO2/N2 (41.7) and CO2/CH4 (6.8) gas mixture pairs was obtained on the O-doped carbon activated with KOH at 600 °C. The excellent separation ability of the O-doped carbons was demonstrated in transient breakthrough simulations of CO2/CH4/N2 mixtures in a fixed bed adsorber. The isosteric adsorption heats of the O-doped carbons were also significantly lower than those of MOF-74 and NaX zeolite. The O-doped microporous carbon adsorbents appear to be a very promising adsorbent for CO2 capture from flue gas, biogas upgrading, and CH4 storage.

CF4 Adsorption on Microporous Carbons Prepared by Carbonization of Poly(vinylidene fluoride)

CF4 is a gas with high global warming potential and has an extremely long atmospheric lifetime. This study developed a method for capturing CF4 gas via adsorption using microporous carbons. Microporous carbon adsorbents were synthesized by a facile protocol involving carbonization of poly(vinylidene fluoride) (PVDF) at high temperatures (400–800 °C) without additional activation, and the effects of carbonization on the characteristics and CF4 adsorption of PVDF-based adsorbents were investigated. Increasing the carbonization temperature enhanced the textural properties of the adsorbent, resulting in the increased CF4 adsorption capacity. Above 700 °C, PVDF was fully dehydrofluorinated, and the microporous carbon synthesized at 800 °C exhibited superior textural properties with a maximum CF4 adsorption capacity of 1.85 mol/kg at 25 °C under atmospheric pressure. The PVDF-based microporous carbons also exhibited fast adsorption–desorption kinetics, excellent cyclic stability, and good selectivity for CF4 ov...

Methane adsorption on microporous carbon adsorbents in the region of supercritical temperatures

Methods for the description of adsorption equilibria for methane on microporous carbon adsorbents within the Dubinin theory of the volume filling of micropores are considered. Isotherms of methane adsorption on eight carbon adsorbents are calculated and compared with the experimental data in the temperature range of 170–350 K at pressures up to 20 MPa. An analysis of the errors of the description of experimental data by the methods used is performed. A method of description based on the use of two isotherms of methane adsorption (at the boiling point and critical temperature) calculated using the Dubinin-Radushkevich equation and the property of the linearity of adsorption isosteres is recommended.

ПОЛУЧЕНИЕ МИКРОПОРИСТЫХ УГЛЕРОДНЫХ АДСОРБЕНТОВ МЕТОДОМ ТЕРМОХИМИЧЕСКОЙ АКТИВАЦИИ ХВОЙНЫХ ОПИЛОК С ПРЕДОБРАБОТКОЙ ОРТОФОСФОРНОЙ КИСЛОТОЙ НА СТАДИИ ПРЕДПИРОЛИЗА

ПОЛУЧЕНИЕ МИКРОПОРИСТЫХ УГЛЕРОДНЫХ АДСОРБЕНТОВ МЕТОДОМ ТЕРМОХИМИЧЕСКОЙ АКТИВАЦИИ ХВОЙНЫХ ОПИЛОК С ПРЕДОБРАБОТКОЙ ОРТОФОСФОРНОЙ КИСЛОТОЙ НА СТАДИИ ПРЕДПИРОЛИЗА

Carbon adsorbents used for gold recovery technology with cyanide

The Dubinin method based on the theory of micropore volume filling was used to study the structural and energetic characteristics of a series of commercial microporous carbon adsorbents used for gold-recovery technology with cyanide. Analysis of microporous structure characteristics showed that the characteristic dimensions of the adsorbents are close to 1.1 nm. The success of applications of the adsorbents for gold-recovery technology is determined by molecular sieve effects applied to cyanide gold complex.

Deformation of AUK microporous carbon adsorbent induced by krypton adsorption

Deformation of AUK microporous carbon adsorbent induced by krypton adsorption

Low-temperature adsorption of methane on microporous AU-1 carbon adsorbent

In this work, isotherms of absolute adsorption of methane on microporous AU-1 carbon adsorbent have been measured in the pressure range from 30 Pa to 6 MPa and temperature range from 178 to 273 K. Adsorption isosteres of methane have been plotted according to experimental data. Isosteres are approximated well by lines in lnp = f(1/T)a coordinates. Differential molar heats of adsorption of methane on this adsorbent have been calculated on the basis of experimental isotherms. Theses regarding the structure of adsorbed substance based on thermodynamic analysis have been proved by molecular-dynamic calculations.

Adsorption of methane on AU-5 microporous carbon adsorbent

Absolute methane adsorption is measured on the AU-5 microporous carbon adsorbent in the pressure range of 20 Pa to 25 MPa and temperature range of 178 to 360 K. Adsorption isosteres in the whole range of pressures and temperatures are well approximated by straight lines that retain a constant slope at a transition to the range of supercritical temperatures under conditions of pronounced gas-phase nonideality. Dependences of differential molar isosteric adsorption heat on the value of methane adsorption on the given adsorbent are calculated. The effectiveness of adsorption storage systems is analyzed, and the optimum a-p-T parameters of methane accumulation are selected.

Adsorption deformation of AUK microporous carbon adsorbent at adsorption of n-heptane

Isotherms of relative linear adsorption deformation are measured on an AUK microporous carbon adsorbent for adsorption of @n-heptane in the pressure range of from 1 Pa to 5 kPa and the temperatures of 273, 293, 313, 353, and 393 K. The curves of adsorption deformation behave in a similar way in the whole range of studied temperatures: the adsorbent is practically not deformed in the range of small and medium fillings and its drastic expansion is observed in the range of high fillings. Numeric simulation of n-heptane adsorption in AUK pores is carried out using the model of slit-shaped pores equivalent to porosity parameters determined on the basis of the Dubinin’s bulk micropore filling theory for AUK. The relationship has been established between adsorption deformation of the adsorbent and adsorbate structure variation in micropores.

Adsorption of methane on AU-1 microporous carbon adsorbent

Isotherms of absolute methane adsorption are measured on the AU-1 microporous carbon adsorbent in the pressure range of 0.2–25 MPa and temperature range of 300–360 K. The experimental data are used to construct isosteres of methane adsorption. Isosteres in the coordinates of lnp = f(1/T)a are well approximated by straight lines. Dependences of differential molar isosteric adsorption heat on the value of methane adsorption on the given adsorbent are calculated on the basis of experimental data. The effectiveness of adsorption storage systems is analyzed, and the optimum a-p-T parameters of methane accumulation are chosen.

Adsorption deformation of a microporous AR-V carbon adsorbent during the adsorption of benzene

Adsorption isotherms of benzene and adsorption-induced deformation of the AR-V microporous carbon adsorbent in the pressure range from 1 Pa to 14 kPa and at temperatures from 255 to 353 K have been determined. Contraction of the AR-V adsorbent is observed at temperatures of 333 and 353 K in the lowpressure area, which changes into expansion with an increase in pressure. In a low-temperature area (255–313 K), only expansion of the AR-V adsorbent is observed in the whole range of the studied pressures. The value of the maximal relative compression of the adsorbent changes from 0.18 to 0.08%, while the corresponding temperature varies from 353 to 333 K. The maximal relative expansion changes from 0.9 to 0.05% along with an increase in the corresponding temperature from 293 to 353 K.

Wave sorbostriction: Waves of adsorption deformation of microporous adsorbent

A new phenomenon is discovered: waves of adsorption deformation or wave sorbostriction of a microporous adsorbent appearing under passage of individual compounds or mixtures thereof in a flow of a carrier gas through it. The method of wave sorbostriction registration is suggested. It is found that the wave amplitude and selectivity of adsorbent sorbostriction depend largely on the mixture composition and physicochemical properties of its components. The suggested method is used to obtain sorbostriction waves of an AR-V microporous carbon adsorbent and passing through it portions of normal hydrocarbons (n-pentane, n-heptane) and their binary mixtures (n-pentane/n-heptane) at the ratios of (50/50) vol % at 473 K in the flow of the He carrier gas. The number of maximums on the sorbostriction curve under the optimum conditions corresponds to the number of components in the mixture.

Adsorption deformation of a microporous AR-V carbon adsorbent during the adsorption of n-hexane

Adsorption isotherms of benzene and adsorption-induced deformation of the AR-V microporous carbon adsorbent in the pressure range from 1 Pa to 14 kPa and at temperatures from 255 to 353 K have been determined. Contraction of the AR-V adsorbent is observed at temperatures of 333 and 353 K in the lowpressure area, which changes into expansion with an increase in pressure. In a low-temperature area (255–313 K), only expansion of the AR-V adsorbent is observed in the whole range of the studied pressures. The value of the maximal relative compression of the adsorbent changes from 0.18 to 0.08%, while the corresponding temperature varies from 353 to 333 K. The maximal relative expansion changes from 0.9 to 0.05% along with an increase in the corresponding temperature from 293 to 353 K.

Adsorption-induced deformation of AUK microporous carbon adsorbent in adsorption of n-pentane

The isotherms of the relative linear adsorption deformation of AUK microporous carbon adsorbent are measured during the n-pentane adsorption within the pressure range of 1 Pa to 50 kPa and at temperatures of 243, 273, 293, 313, 353, and 393 K. The curves of adsorption deformation have similar behavior within the whole range of investigated temperatures. Except for the initial pressure range p < 400 Pa, the adsorption deformation increases as pressure grows and reduces as temperature grows. The effects of adsorption deformation manifest extremely weakly at pressures of less than 400 Pa. Nevertheless, in this pressure range, at temperatures below 350 K, the initial compression of adsorbent (0.01%) is observed, which increases as temperature reduces. At higher temperatures, the sharp initial adsorbent expansion by 0.002% is observed, which transfers them to a narrow region of deformation constancy. Beyond this region, the adsorbent expands in all temperature ranges as the pressure increases.

Adsorption of hexane, cyclohexane, and benzene on microporous carbon obtained by pyrolysis of hypercrosslinked polystyrene

The relationships of adsorption of hexane, cyclohexane, and benzene on a D4609 microporous carbon adsorbent obtained by the pyrolysis of hypercrosslinked polystyrene are compared. It is shown that in the range of relative pressures corresponding to the filling of ultramicropores, the adsorption behaviors of cyclohexane and benzene are essentially identical, in contrast to hexane, which is characterized by higher adsorption values and isosteric heat of adsorption. The observed relationships are explained by the steric features of the distribution of molecules of various structures in ultramicropores.

Adsorption of tetrachloride carbon on microporous AP-B carbon sorbent

The adsorption isotherms of tetrachloride carbon on microporous AP-B carbon adsorbent are measured and the differential isosteric heats of adsorption over the pressure range of 1–14 000 Pa at temperatures of 255.5–352.8 K are calculated. The adsorption isotherms with increasing temperature almost symbatically shift toward higher pressures and have an adsorption hysteresis loop in the range of high adsorption values on the isotherms at 255.5, 272.9, and 292.8 K. The adsorption isosters are shown to be well approximated by straight lines over the entire range of pressures and temperatures. The analysis of the applicability of the Dubinin-Radushkevich thermal equation of adsorption is carried out and the best description of the experimental data is shown to be attained when considering the temperature dependence of the characteristic energy of adsorption.

Microporous carbon adsorbents with high CO2 capacities for industrial applications

In this study we attempt to investigate the potential use of two zeolite template carbon (ZTC), EMT-ZTC and FAU-ZTC, to capture CO(2) at room temperature. We report their high pressure CO(2) adsorption isotherms (273 K) that show for FAU-ZTC the highest carbon capture capacity among published carbonaceous materials and competitive data with the best organic and inorganic adsorbing frameworks ever-known (zeolites and mesoporous silicas, COFs and MOFs). The importance of these results is discussed in light of mitigation of CO(2) emissions. In addition to these new experimental CO(2) adsorption data, we also present new insight into the adsorption process of the two structures by Monte Carlo simulations: we propose that two separate effects are responsible for the apparent similarity of the adsorption behaviour of the two structures: (i) pore blocking occurring on EMT-ZTC, and (ii) the change of the carbon polarizability due to the extreme curvature of FAU-ZTC.

Krypton adsorption on microporous adsorbents at higher pressures

The krypton adsorption isotherms were measured on AUK microporous carbon adsorbent in the range of pressures from 1 Pa to 6 MPa and temperatures of 177.7—393 K. With adsorption isotherms in the same range of pressures and temperatures, the krypton adsorption isosteres were calculated. The derived curves are well approximated with linear functions. With the adsorption isosteres, differential molar isosteric adsorption heat curves were plotted vs. adsorption and temperature. The received results were compared with the reference data of the krypton adsorption on Carbolac active carbon.