A molecular simulation study of commensurate – incommensurate adsorption of n-alkanes in cobalt formate frameworks

Rajamani Krishna (1) , Jasper Martijn van Baten (1)

1 van ‘t Hoff Institute for Molecular Sciences

The channels of the cobalt formate frameworks consist of one-dimensional channels that have a zig-zag configuration. Propane (C3) has a length that is commensurate with the channel segment length; longer n-alkanes such as n-butane (nC4), n-pentane (nC5) and n-hexane (nC6) have conformations that straddle two channels segments. Configurational-bias Monte Carlo (CBMC) simulations show that the adsorption strength of C3 is higher than that of n-butane (nC4), and n-pentane (nC5); this unusual hierarchy is a direct consequence of commensurate – incommensurate adsorption. CBMC simulations also reveal the possibility of separating C3-nC6,C3-nC4, nC4-nC6, nC4-nC5 liquid mixtures for which the adsorbed phase contains predominantly the shorter alkane. Molecular dynamics (MD) simulations show that the hierarchy of self-diffusivities is non-monotonic and is the mirror image of the hierarchy of adsorption strengths.

Mots clés: Physical Sciences

Rajamani Krishna, Jasper Martijn van Baten. A molecular simulation study of commensurate – incommensurate adsorption of n-alkanes in cobalt formate frameworks. Molecular Simulation, 2009, 35 (12-13), pp.1098-1104. ⟨10.1080/08927020902744672⟩. ⟨hal-00530446⟩