Adsorption of alkanes, alkenes, and their mixtures in single-walled carbon nanotubes and bundles

Sven Jakobtorweihen (1) , Frerich J. Keil (2)

1 Institute of Chemical Reaction Engineering
2 Institute of Chemical Reaction Engineering

Monte Carlo simulations are employed to calculate pure component adsorption isotherms of linear alkanes (C2-C12), alkenes (C2-C4), and some of their binary mixtures (ethane-ethene, propane-propene, cis-2-butene-trans-2-butene, propene-1-butene) in single-walled carbon nanotubes. The zigzag structures of carbon nanotubes of various diameters ((10,0), (20,0), (30,0), and (40,0)) are used. Furthermore, Henry coefficients and isosteric heats of adsorption are calculated. The dependence of theses properties as a function of chain length (carbon number) is presented. The relation of the critical parameters and the isosteric heats of adsorption, observed earlier for zeolites, could be confirmed for carbon nanotubes. The adsorption behaviour of 1-butene, cis-2-butene, and trans-2-butene are compared in detail. Radial density profiles of 1-butene in a (40,0) nanotube for various pressures reveal a built-up of three layers inside the pores with increasing pressure. For all investigated binary mixtures, one of the component isotherms shows a distinct maximum owing to a entropic effect and non-idealities of the bulk gas phase behaviour. Additionally, adsorption in carbon nanotube bundles in hexagonal arrangement is studied. Depending on the pore arrangements, pore diameters, and pressures, a fraction of the adsorbed gases is located in the interstitial space.

Mots clés: Physical Sciences

Sven Jakobtorweihen, Frerich J. Keil. Adsorption of alkanes, alkenes, and their mixtures in single-walled carbon nanotubes and bundles. Molecular Simulation, 2009, 35 (01-02), pp.90-99. ⟨10.1080/08927020802378936⟩. ⟨hal-00515053⟩