Adsorption processes for CO2 capture from flue gas using polyaniline solid sorbent

Abstract

In this simulation study, the temperature swing adsorption (TSA) process and the pressure swing adsorption (PSA) process were utilized to separate flue gas (15.03% CO₂ and 84.97% N₂) from a power plant with a solid polyaniline sorbent. CO₂ can be recovered and sequestrated to reduce greenhouse-gas effects. The method of lines is utilized, combined with upwind differences, cubic spline approximation and LSODE of ODEPACK software to solve the problem. The concentration, temperature, and adsorption quantity in the bed are integrated with respect to time by LSODE of ODEPACK software. The simulation is stopped when the system reaches a cyclic steady state. In this study, experimental data was first regressed to obtain the parameters of the isotherm curves; then the breakthrough curve of the solid polyaniline sorbent was simulated. The feasibility of the adsorption process simulation program became obvious through a comparison of the experimental and simulation results. Four different processes were used in this study: the single-bed five-step TSA process, the single-bed two-step PSA process, the single-bed three-step PSA process and the dual-bed six-step PSA process. The optimal operating conditions were obtained by varying the operating variables, such as adsorption temperature, desorption temperature, feed pressure, bed length, step time, etc. After the variables discussion, the best process is found to be the single-bed three-step PSA process and the best operating conditions are a feed pressure of 6.0 atm, a co-current depressurization pressure of 1.0 atm, a vacuum pressure of 0.1 atm, a bed length of 98.3 cm and step times of 1200, 10 and 500 s. The results of the aforementioned operating conditions are 97.13% purity and 87.26% recovery of CO₂.