Separation Science and Technology, Vol.49, No.4, 490-498, 2014
Removal of Carbon Dioxide from Light Gas Mixtures using a Porous Strontium(II) Silicoaluminophosphate Fixed Bed: Closed Volume and Portable Applications
A Sr2+ -SAPO-34 bed was assembled to study CO2 dynamic adsorption under conditions that emulate those found in closed volume and portable applications. Although the surface area was reduced by 7% during pelletization, adsorption capacities estimated from breakthrough curves compared well with static volumetric adsorption data. Modeling of the breakthrough adsorption was achieved using a Linear Driving Force mass transfer rate model, showing good agreement with the experimental data and confirming fast kinetics and efficient use of the bed. Fast kinetics were also evidenced by the length of the unused section of the bed as calculated from a Mass Transfer Zone model. Adsorption capacity degradation was not observed after multiple regeneration cycles. Apparent and equilibrium adsorption isotherm data estimated from the bed and static volumetric experiments at 25 degrees C were compared to that of 5A Zeolite. These showed that Sr2+ -SAPO-34 is a superior adsorbent for CO2 removal in the low partial pressure range (<1500ppm). CO2 and H-2 O multicomponent adsorption breakthrough curves were also gathered for a CO2 inlet concentration of 1000ppm and dew points of -5 and 8 degrees C. The addition of moisture resulted in a decrease in total processed gas volume by 31 and 47%, respectively.
Keywords:packed bed;separations;silicoaluminophosphate;adsorption;carbon dioxide;atmospheric revitalization