Separation of CO2/N2 on binderless 5A zeolite

The study of CO2 separation from typical flue gas streams containing other gases like N2, CO, H2 and CH4 by Pressure Swing Adsorption (PSA) process using binderless 5A zeolite beads as adsorbent is the main objective of this work. Firstly, single component adsorption equilibrium isotherms of CO2, CH4, N2, CO and H2 have been determined by gravimetric technique in a magnetic suspension microbalance (Rubotherm®) at three different temperatures (305, 333, and 363 K), up to 5 bar. A comparison between the obtained adsorption equilibrium data and reported values in the literature for other 5A zeolite adsorbents was performed. Dynamic studies were also done through single and binary breakthrough curves of N2, CO, H2 and CH4 at 4 bar and 308 K. A PSA experiment was performed, at pilot scale, with the aim of validating the developed PSA model for CO2 capture with the binderless 5A zeolite adsorbent. The adsorption equilibrium isotherms were fitted with the Toth model and breakthrough curves and the PSA experiment were simulated taking into account the adsorption dynamic behaviour of a fixed bed. CO2 recovery values between 81 and 98% and energy consumption between 5.7 and 3.8 MJ/kgCO2, for purification of a stream containing 10% of CO2 by different PTSA cycles were attained. For all designed PTSA cycles the product purity was higher than 95% in CO2; and the productivity was always above 13 kg/mbed3/h. The best results are obtained with a high pressure of 3.5 bar, a low pressure of 0.3 bar and a heating temperature of 403 K. For these operating conditions the lowest value of energy consumption is obtained (3.8 MJ/kgCO2) with a high CO2 recovery (94.8%) and high CO2 purity (95.2%). The achieved productivity was of 16 kg/mbed3/h.