Prediction for adsorption of multi-component gas of coals and comparative study of different adsorption models

To accurately describe the process of multi-component gas adsorption that is related to the studies of enhanced coalbed methane (ECBM) or carbon dioxide coal sequestration, we use respectively the extended Langmuir equation, ideal adsorbed solution (IAS) model and the two dimensional equation of state (2D EOS) to predict the adsorption of methane-carbon dioxide mixed gas on coal and activated carbon. Then, we compare the results predicted with the previous experimental data from literature. It is demonstrated that 2D EOS model can achieve the highest prediction accuracy and be more suitable to predict the multi-component gas adsorption in high pressure system. In addition, from the trends of separation factor for three models, we have known that both the IAS and 2D EOS models can take the changes of gas relative adsorption to equilibrium gas components and pressure into consideration, but extended Langmuir does not consider the factor. So IAS and 2D EOS models have the greater advantage that can better predict the gas relative adsorption over extended Langmuir.