Fundamental And Application Research Of CO₂ And H₂O Competitive Adsorption On Carbon Capture

Based on the structural characteristics and physicochemical characteristics of porous nanomaterials,the CO₂ adsorption and separation under moisture-source carbon capture technology can be realized.H₂O will cause CO₂ capture rate to decrease or even fail,it also causes the capture system to produce many adverse effects such as temperature drop and pressure drop,which will eventually lead to a substantial increase in additional energy consumption and costs.Firstly,the mechanism of co-adsorption of CO₂ and H₂O dispersed was summarized from macro and micro levels.according to the fundamental research of co-adsorption mechanism,the progress in the fields of competitive adsorption,moisture swing adsorption and“breathing effect”were reviewed and briefly evaluated.Based on the application research of co-adsorption mechanism,the status and progress of adsorbent development and technology improvement of wet gas CO2 adsorption were described.Then,the thermodynamic carbon pump model of CO₂/H₂O competitive adsorption form micro level was established.Based on the gas separation theory,the Monte Carlo simulation（MC）and Density Functional Theory（DFT）were used to develop a new method to calculate the properties of porous nanomaterials and evaluate the thermodynamic performance of adsorption materials,such as zeolites and metal organic frameworks（MOFs）.The results show that the co-adsorption of CO₂ and H₂O is driven by the adsorption enthalpy and adsorption entropy.Besides,the significant difference between adsorption enthalpy values of CO₂ and H₂O is due to the different interaction mechanism with adsorbent.On the one hand,the hydrogen bond interaction of H₂O molecule is stronger than the dispersion force,on the other hand,the coverage is also an important variable to change the adsorption enthalpy.Finally,the mixed gas separation model and circulation model were used to evaluate the separation performance and energy efficiency of temperature swing adsorption.When the partial pressure of water vapor is far less than the saturation pressure,the CO₂ recovery is almost not affected by H₂O,and there is a good linear relationship between the CO₂ purity and CO₂ recovery.It should be emphasized that the difference of Gibbs free adsorption energy between CO₂ and H₂O has a significant relationship with energy consumption:whenΔG_H2O<ΔG_CO2<0,the CO₂ energy consumption increases with the increase ofΔG_H2O-ΔG_CO2;whenΔG_CO2<ΔG_H2O<0,the energy consumption will increase in the opposite direction,and there is a range of-3～0kJ/mol that makes the value reach the lowest.