Stability of the adsorption properties of the metal-organic framework HKUST-1

Russian Chemical Bulletin - Adsorption isotherms of methane for two samples of the metal-organic framework HKUST-1 with copper ions were measured on a precise vacuum high-pressure...     

Methane adsorption on microporous carbon adsorbent with wide pore size distribution

Methane adsorption on a microporous carbon adsorbent with a bimodal pore size distribution is studied at temperatures of 303–333 K at pressures up to 30 MPa. The total micropore volume of the adsorbent, as determined by the Dubinin method, is as large as 1.02 cm³/g. Maximum values of methane adsorption of ≈18 mmol/g are attained at a temperature of 303 K and a pressure of 30 MPa. Methane adsorption isosteres are plotted based on experimental data, and adsorption equilibria at low temperatures are calculated using the linearity of the plots. Experimental isotherms of methane adsorption are compared with the isotherms calculated by the Dubinin–Nikolaev equation with variations in parameters E and n. Temperature dependences of these parameters are determined. Specific characteristics of methane adsorption accumulation are calculated.     

Methane adsorption on various metal-organic frameworks and determination of the average adsorption heats at supercritical temperatures and pressures

Adsorption of methane on three samples of metal-organic framework structures (MOF), which contain copper, aluminum or zinc atoms, was measured at temperatures ranging from 303 to 333 K and pressures up to 40 MPa using a precise volumetric-gravimetric unit. The determined values of adsorption volumes and characteristic energies served to evaluate the average heats of adsorption, which were compared to the average isosteric heats of adsorption.     

Sorption of butane, propane, ethane, methane, and carbon dioxide on asphaltene

Isotherms of sorption of butane, propane, ethane, methane, and carbon dioxide on an asphaltene sample of known elemental composition were measured. The effect of the pressure and temperature on the shape the sorption isotherms for all the adsorption systems studied was examined. The values of the initial heat of sorption were determined and compared to the energies of interaction of the molecules with asphaltene. The results obtained suggest that asphaltene is a swellable amorphous sorbent.     

Porous structure of synthetic opals

Some adsorption, structural, and annihilation characteristics of synthetic opals are measured. An analysis of these characteristics makes it possible to conclude that the total porosity in opals comprises macropores, which are in essence the voids between structure-forming spheres, and nanopores connected to the substructure of the spheres. The systems of macropores and nanopores are separated by narrow channels that collapse upon the thermal treatment of opals. The sizes of primary a-SiO₂ particles and nanopores, which correspond to the voids between these particles, are estimated.     

New method for the determination of adsorption space volume for sorbents with an arbitrary porous structure from excess gas adsorption isotherm measurements

A new method for the determination of adsorption space volume has been proposed, which is applicable to adsorbents with an arbitrary porous structure, including nonporous adsorbents with open surfaces. The method is based on the use of an experimental excess adsorption isotherm measured over a wide range of pressures in the equilibrium gaseous phase (as a rule up to 100–150 MPa) and the absolute adsorption isotherm equation with unspecified parameters in the most general form, given by statistical physics. The method has been tested for a number of adsorption systems, and it has been found that the result was always unambiguous, correct, and stable in the sense of input data.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2381–2385, December, 1995.