1204 ISSN 0036-0244, Russian Journal of Physical Chemistry A, 2009, Vol. 83, No. 7, pp. 1204–1207. © Pleiades Publishing, Ltd., 2009. Original Russian Text © L.D. Asnin, V.A. Davankov, A.V. Pastukhov, K. Kaczmarski, 2009, published in Zhurnal Fizicheskoi Khimii, 2009, Vol. 83, No. 7, pp. 1356–1359. INTRODUCTION Carbon materials obtained by the pyrolysis of hypercrosslinked polystyrenes to a substantial extent inherit the general morphology and fine porous struc- ture of the initial polymers. This results in the presence of sieve properties, which determine the ability to sep- arate inorganic electrolytes [1], a developed surface, high strength characteristics, and a regular spherical shape of granules [2, 3]. The behavior of these adsor- bents brought in contact with organic substance vapors was not discussed in detail. The “initial” (at zero filling) thermodynamic characteristics of adsorption of several test organic molecules on sulfonated hypercrosslinked polystyrene carbonizates were studied chromatograph- ically [2]. Although such studies allow us to draw con- clusions about the nature of the surface of adsorbents, they give no information about the relation between the porous structure of materials and their adsorption prop- erties. In [4], the isotherms of adsorption of chloroben- zene vapor on D4609 pyrolysis carbon from Purolite Int. (Great Britain) were measured at various tempera- tures over a wide range of degrees of filling and ana- lyzed. As a continuation to these studies, we used elu- tion chromatography to study the adsorption of ben- zene on the same adsorbent. Because of limitations of the technique used, measurements cover a narrow ini- tial region of degrees of filling. On the other hand, this allowed us to thoroughly study the part of isotherm cor- responding to the adsorption of vapor in the narrowest pores. EXPERIMENTAL Adsorption isotherms were measured by the Glukauf method [5] over the temperature range 140– 170°ë on a Tsvet-530 chromatograph with a flame ion- ization detector connected to a PowerGraph 2.0 com- puter system for data accumulation by an E24 analog- to-digital converter (L-card, Moscow). An adsorbent sample (fraction 0.25–0.5 mm, 0.296 g) was loaded into a sorption tube made of stainless steel, inside diam- eter 0.3 cm, length 9 cm. A glass insert was placed into the vaporizer of the chromatograph to decrease the dead volume determined against methane. The corre- sponding correction was introduced into measurement results. Prior to measurements, the sample was condi- tioned for 5 h in a flow of a carrier gas at 200°ë. The carrier gas was nitrogen of special purity additionally dried with alumina and zeolite CaA. The flow rate was 30 cm 3 /min; it was controlled using a soap-foam flow- meter. Benzene of kh. ch. (chemically pure) grade was distilled over freshly calcined zeolite NaA. The adsor- bate was introduced using Hamilton-1, Hamilton-5, and MSh-10 syringes for probe volumes of 0–1, 2–5, and 6–10 μl, respectively. Since the complete elution of the adsorbate takes much time (10–20 h), the determination of adsorption isotherms for probes with different volumes was per- formed at 160°ë. For the other temperatures, the iso- therms were calculated from the dispersed rear of the peak obtained after the injection of the largest benzene volume (10 μl). It follows from Fig. 1 that isotherms of adsorption at 160°ë determined by these two methods The Thermodynamics of Benzene Adsorption on Carbon Obtained by the Pyrolysis of Hypercrosslinked Polystyrene L. D. Asnin a , V. A. Davankov b , A. V. Pastukhov b , and K. Kaczmarski c a Institute of Technical Chemistry, Ural Division, Russian Academy of Sciences, ul. Lenina 13, Perm, 614600 Russia b Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, ul. Vavilova 28, Moscow, GSP-1, 117813 Russia c Rzeszow Technological University, Rzeszow, Poland e-mail: asninld@mail.ru Received June 19, 2008 Abstract—The Glukauf chromatography method was used to study the adsorption of benzene on a microporous carbon material prepared by the pyrolysis of hypercrosslinked polystyrene. The thermodynamic characteristics of adsorption were determined as functions of the degree of pore filling. Over the range of rela- tive pressures studied (<0.005), adsorption was shown to occur in ultramicropores by the mechanism of primary filling without condensed phase formation. DOI: 10.1134/S0036024409070279 PHYSICAL CHEMISTRY OF SURFACE PHENOMENA