(396h) Structured Adsorbents with High CO2 Over N2 Selectivity and CO2 Uptake Capacity

Farid Akhtar, Neda Keshavarzi, Arto Ojuva, Niklas Hedin, Lennart Bergström

Department of Materials and Environmental Chemistry, Stockholm University, Stockholm

SE-10691, Sweden

Berzelii Center EXSELENT on Porous Materials, Stockholm University, Stockholm 10691, Sweden

Abstract

Structured adsorbents with high CO₂ adsorption capacity, CO₂ over N₂ selectivity and rapid adsorption and desorption kinetics are ideal for CO₂ capture from power-plant flue gas at a low cost. We report here binder-free zeolite monoliths with high CO₂ over N₂ selectivity (> 500) and uptake capacity (4mmolg^-1) at 298 K and 101 kPa. Binder-free zeolite monoliths were consolidated by a rapid and facile processing approach called pulse current processing (PCP) from partially K exchanged NaA powders. The pore widow size of NaA was optimized by partially exchanging Na with K cations to achieve a high CO₂ over N₂ selectivity while maintaining a high CO₂ uptake capacity. The CO₂ uptake from binary mixtures of 0.10CO₂-0.90N₂ was obtained from the single component CO₂ and N₂ adsorption isotherms by applying Ideal adsorption solution (IAS) and Fast IAS theories. The binder-free adsorbents with an optimum degree of ion exchange display extraordinarily high CO₂ over N₂ selectivity and high CO₂ uptake, together with a rapid CO₂ adsorption and desorption kinetics and high mechanical stability. The performance of the new adsorbent has been compared with other potential candidates for efficient swing adsorption processes by a figure of merit.   

Key words: CO₂ Capture; Zeolite monoliths; Pulse current processing; Selectivity; Adsorption; Ideal adsorbed solution (IAS) theory.