Performance Evaluation of Static and Dynamic CO₂ Adsorption from Synthetic Gas Condensates Using Zinc Oxide, Silicon Dioxide and Zeolite 13X

This paper evaluated ZnO, SiO₂ and zeolite 13X for removing CO₂ from normal heptane (nC₇) as synthetic gas condensates in batch mode. Based on the results of CO₂ adsorption isotherms, zeolite 13X had the highest CO₂ uptake in 1400–3700 ppm at atmospheric pressure. Due to the higher specific surface area of granular zeolite 13X, its CO₂ uptake was more than that of zeolite 13X powder. Also, the CO₂ adsorption equilibrium time was less than 30 min for zeolite 13X powder. The selectivity of zeolite 13X powder (i.e., H₂S/CO₂) was 2.36–4.08 for 2001–3930 ppm H₂S with 1668 ppm CO₂. Besides, the CO₂ breakthrough time for zeolite 13X powder was 50–4 min for WHSV (weight hourly space velocity) = 5–20 h⁻¹ at 30 bar in continuous mode. Additionally, for the increased CO₂ concentration from 1000 to 3000 ppm, the CO₂ breakthrough time decreased from 30 to 11 min with WHSV = 10 h⁻¹. The CO₂ breakthrough time diminished by 2.5-fold as the pressure was reduced from 30 bar to atmosphere for the initial CO₂ concentration of 1000 ppm in nC₇ and WHSV = 10 h⁻¹. Subsequently, the regeneration of zeolite 13X by stagnant hot air was investigated for the CO₂ concentration range of 1000–3000 ppm, air-adsorbent contact time range of 30–180 min and temperature range of 100–300 °C using Box–Behnken design. Its regeneration efficiency was more than 95% for the CO₂ concentration below 1000 ppm.