Comparison of structured activated carbon and traditional adsorbents for purification of H2

Abstract

RPSA technology can offer a more compact, cost-effective and energy-efficient solution for H2 recovery when compared to conventional PSA. The adsorption rate of adsorbents has become a key factor affecting the development of RPSA. Activated carbon, widely used as adsorbent for CO2 in H2 purification is in urgent need for further development to suitable for RPSA system. In this study, a structured activated carbon adsorbent was prepared using the dip-coating method, with nickel foam as a framework. The adsorption characteristics of the material for CO2 adsorption at different adsorption pressures, volume flow rates, and lamellar spacing parameters were investigated, and the kinetic behaviour was studied by the breakthrough curve. The results showed that the activated carbon was bonded to the nickel foam skeleton via an organic-inorganic binder with excellent mechanical strength. Structured adsorbents bed has uniform gas flow distribution, the pressure drop is about 1/3–1/7 of particles packed bed, and the breakthrough curve was sharper than particles. It indicated that the mass-transfer resistance in the structured adsorbents is low and has high effective diffusivity for CO2. The adsorption rate constant was calculated using the Yoon-Nelson model, and the correlation between the model calculation data and experimental data was greater than 0.98. Structured activated carbon adsorbent manufactured by dip-coating method, has a higher mass transfer coefficient and a shorter mass transfer zone length. It is a potential alternative adsorbent for RPSA.