Thermodynamic Studies On Carbon Dioxide Absorption

The emission of carbon dioxide (CO₂) has been identified as the major contributor to global warming and climate changing. The challenging for the modern industry is to find cost-effective solutions that will reduce the release of CO₂ into the atmosphere. The CO₂ capture can be achieved by a variety of means. The Physical absorption process is one of the most important means for requiring relatively less energy. Choosing the excellent absorbent is the point in the way, the absorbent must have a high solubility with CO₂, selectivity, esay to desorption, high boiling point, noncorrosive, non-toxicity and performance steady. Thermodynamic property of CO₂ absorption process was studied in the paper. The research effort included choosing CO₂ physical absorbent, Vapor-Liquid Equilibrium(VLE) experiment for the system carbon dioxide-diisopropyl ether and building VLE model.The Vapor-Liquid Equilibrium data comprise CO₂ was introduced. Equilibrium ratio was calculated basing on the data of references, activity coefficient and the maximal excess Gibbs function were simulated by ASPEN PLUS. Then to study and compare these data, the method for solvent choice was established: the solvent made the maximal excess Gibbs function and the infinite dilution activity coefficient less is the perfect absorbent. Diisopropyl ether was chosen as CO₂ absorbent according to this way.Vapor-Liquid Equilibrium measurement for carbon dioxide with diisopropyl ether is presented at temperature 265.15K to 333.15K and pressures 0.5 MPa to 2.5 MPa. The experimental data were all subjected to the thermodynamics consistency test, and the validity of the experimental data for these systems was proved.The Vapor-Liquid Equilibrium data are correlated with the cubic type Peng-Robinson equations of state. The measured data in the study agrees well with calculated data and the reliability of the apparatus in the study is confirmed.In the range of experimental temperature, the liquid mole fraction of carbon dioxide fluctuates obviously, especially in the state of low temperature. It is testified that diisopropyl ether is an excellent absorbent to absorb carbon dioxide. So, diisopropyl ether, which has considerable potential acting as a new carbon dioxide absorbent, is worthy of research.