Adsorption-Induced Deformation of Microporous Carbons: Pore Size Distribution Effect due to Adsorption of a Binary Gas Mixture

VALERIA CORNETTE; J.C. ALEXANDRE DE OLIVEIRA; D.C.S. AZEVEDO; R. H. LÓPEZ

Rio de Janeiro

Congreso; Carbon 2013; 2013

The American Carbon Society and the Brazilian Carbon Association

Gas adsorption in porous solids is known to induce elastic deformation, and this is well-documented in the literature. In microporous materials such as carbons and zeolites the induced strain is usually very small, of the order of 10-3,[1] and this effect has thus often been neglected in the past discussions and modeling studies of adsorption experiments. However, this implies large internal stresses on the order of megapascals[2]. Although mechanical properties of microporous carbons are critically important for various technological applications, such as characterization of porous materials, equilibrium separation of fluid mixtures by porous sieves, and so on[3], [4], the basic mechanisms of deformation during the adsorption desorption processes are still not completely understood. Kowalczyk et al. [5?7] in particular showed that deformation effect caused by argon, carbon dioxide and methane adsorption in micropores may be highly sensitive to the micropore size distribution of the material under investigation and the kind of adsorbate applied. However, not many works have been devoted to analysis the solvation or disjoining pressure as applied to adsorption of a binary gas mixture. Recently, Brochard et al. [8] simulated the competitive adsorption of carbon dioxide and methane in CS1000 (a realistic model for microporous coal) and concluded that the competitive adsorption of the two fluids in the coal micropores is responsible for the differential swelling phenomenon, a major problem for field application of enhanced coal bed methane recovery (ECBM). Furthermore the adsorptive separation of gases is an important process in many industrial and environmental applications. In particular, the separation of CO2 from CO2-CH4 mixtures is a fundamental problem in natural gas and biogas purification/upgrading in energy generation applications [9], [10].