V. A. Sinitsyn

Adsorption and adsorption-induced deformation of NaX zeolite under high pressures of carbon dioxide

Isotherms of carbon dioxide adsorption and adsorption-induced deformation of pelletized crystalline NaX zeolite at pressures of 0.2--5.4 MPa and temperatures of 195--423 K are measured. The adsorption deformation is positive at low zeolite micropore filling (a < 1 mmol g-1) at all temperatures, i.e., the zeolite suffers expansion. Further, as the amount of the adsorbed substance increases, the adsorption deformation curves pass first through a maximum and then through a minimum. In the range of high fillings (a > 7 mmol g-1) the NaX zeolite shows dramatic expansion.

Adsorption deformation in the microporous carbon adsorbent-benzene system and porous structure of adsorbents

The relative adsorption deformation of several microporous carbon adsorbents was studied as a function of the benzene adsorption at relative pressure ranging from 1·10−1 to 1.0 and at 293 K. A correlation between the maximum compression of the sample and the characteristic energy of benzene adsorption of the Dubinin-Radushkevich equation was obtained. Using data on the adsorption deformation, it is possible to identify the region with a specific pore size that cannot be evaluated with the help of the Dubinin-Radushkevich equation.

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-stimulated deformation of microporous carbon adsorbent

Deformation of the ACC microporous carbon adsorbent during adsorption of carbon dioxide, nitrogen, and argon in the temperature interval from 243 to 393 K and at pressures of 1—5·106 Pa was studied. The effect of adsorbent contraction was found in the initial temperature interval at relatively low pressures. However, the negative value of relative linear deformation ΔL/L smoothly transforms into positive values with the pressure increase. Only the effect of adsorbent expansion is observed at high temperatures in the whole pressure interval. The dependence of the deformation effects for different systems on the adsorbent nature was revealed.

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.

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.

Nitrogen adsorption by microporous adsorbents in the range of high pressures and supercritical temperatures

The nitrogen adsorption isotherms for the AUK microporous carbon adsorbent are measured at pressures of 1 Pa to 6 MPa and temperature of 177.7–393 K. In terms of the adsorption isotherms, in the same range of pressures and temperatures, the nitrogen adsorption isosteres are calculated. The resultant dependences are adequately approximated by linear functions. By the adsorption isosteres, the dependences of differential molar isosteric heat of adsorption on the value of adsorption and temperature are plotted. The results are compared with the literature data on nitrogen adsorption by zeolite NaX and activated carbon SKT.

Adsorption of n-pentane on a microporous carbon adsorbent with a narrow pore size distribution

A model of thermochemical synthesis of a microporous carbon adsorbent of silicon carbide is developed. Isotherms of absolute adsorption of n-pentane on an AUK microporous carbon adsorbent of SiC with a narrow pore size distribution are measured in the pressure range of 1 Pa to 50 kPa and in the temperature interval of 243–393 K. The parameters of adsorption equilibrium of the adsorption isostere calculated in the same range are adequately approximated by straight lines. The differential molar isosteric heat of adsorption of n-pentane on the AUK adsorbent decreases of 58-46 kJ/mol in the whole region of micropore filling; this fact counts in favor of energetic heterogeneity in the micropores, which presumably appears in the process of thermochemical synthesis of the microporous carbon adsorbent of silicon carbide.

Adsorption of perfluoropropane on the PAC microporous carbon adsorbent

The adsorption of perfluoropropane (N3F8) on the PAC microporous carbon adsorbent, which is close in properties to monoporous adsorbents, was studied at temperatures of 216, 243, 295, 318, and 343 K in the pressure interval from 1 to 1·105 Pa. The adsorption isosters are well approximated by straight lines in the studied interval of temperatures and pressures. The dependence of the isosteric heats of adsorption on filling is described by a curve with a maximum in the region of high fillings. Such a curve is characteristic of adsorbents with a narrow pore size distribution.

Adsorption of carbon dioxide on microporous carbon adsorbent PAU-10

Carbon dioxide adsorption on the microporous carbon adsorbent PAU-10 within the 177.8—423 K temperature and 0.1—5.13·106 Pa pressure intervals was studied. The isosteres of absolute adsorption are well approximated by straight lines, which do not change their slope on going to temperatures higher than the critical temperature of CO2. An increase in the differential molar isosteric heat of adsorption (qst) at 0 < a < 1 mmol g−1 is explained by the influence of the endothermic effect of adsorption expansion of the adsorbent. In the region of high pressures and nonideal gas phase, qst is temperature-dependent.