Influence of carbon uniformity on its characteristics and adsorption capacities of CO2 and CH4 gases

Abstract

Activated carbons of resorcinol-formaldehyde aerogels (AC-RFA) were prepared and mixed with multiwall carbon nanotubes (MWCNTs) with various ratios. Samples were characterized by different techniques. The novelty of the study is in evaluating the effect of uniformity of carbon nanocomposites on their performance for the adsorption of CH4 and CO2 gases as well predicting the separation of their mixtures. The results indicated that, by increasing the percentage of MWCNTs into the sample, its structural uniformity and order ascend. The capacities of CH4 and CO2 by adsorption were measured at various temperatures, and were correlated with the extended dual site Langmuir (DSL) model. Overall, results showed that the adsorption capacity of MWCNTs towards gases is relatively very low compared to that of activated carbons. The DSL model was utilized to forecast the separation of the binary CO2/CH4 mixed gas based on knowledge of single component adsorption isotherm parameters. Adsorption equilibrium data of the CO2/CH4 binary gas mixture was forecasted at different temperatures by DSL model in accordance with the perfect-negative (PN) or perfect-positive (PP) behaviors on the heterogeneous surface of the adsorbent.