Methane separation from diluted mixtures by fixed bed adsorption using MOFs: Model validation and parametric studies

Abstract

Adsorption of methane from diluted methane/nitrogen mixtures in a fixed bed reactor was experimentally studied and modelled in this work. Three different Metal-Organic Frameworks (MOFs), Basolite C300, F300 and A100 were considered for this purpose, the adsorption bed being operated at 298 K, 0.1 MPa, and an inlet methane concentration of 2%. Methane adsorption capacities decrease in the order: Basolite C300 (0.078 mmol/ g) > Basolite F300 (0.040 mmol/g) > Basolite A100 (0.028 mmol/g). In addition, a mechanistic model based on the numerical solution of an heterogeneous one-dimensional model considering axial dispersion has been used for modelling these adsorption results. Proposed model provides a reasonable fitting of the experimental fixed bed results (R2 > 0.9), using internal diffusion and axial dispersion as fitting parameters. Variation of these parameters can be explained in terms of adsorbent morphological features. Proposed model has been successfully extended to other methane adsorption processes reported in the literature, as well as to thermal desorption of methane from MOF-containing fixed bed reactors. The experimentally validated model has been used to predict the effect of main operation parameters on the performance of the MOF-based fixed beds for methane adsorption.