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<p>ETS-4 titanosilicate adsorbent with unique characteristics is very suitable for CO<sub>2</sub> adsorption. However, it is still necessary to study the adsorption performance details and regeneration performance of this adsorbent as well as its ion-exchange type Sr-ETS-4 and the effect of the activation temperature for CO<sub>2</sub>/CH<sub>4</sub> separation and post-combustion CO<sub>2</sub> capture (CO<sub>2</sub>/N<sub>2</sub> separation). In the present work, CO<sub>2</sub>, CH<sub>4</sub>, and N<sub>2</sub> adsorption equilibria for the synthesized ETS-4 and Sr-exchanged ETS-4 were measured at 25&#xa0;°C. Adsorption data were used for modeling to predict the phase diagram, selectivity, and total adsorption of samples in binary mixtures with the IAST method. Also, the CO<sub>2</sub> adsorption kinetics data were measured and investigated by micropore diffusion and Pseudo-n<sup>th</sup>-Order (PNO) models. The results showed that ion exchange with strontium enhanced significantly the thermal stability of ETS-4. Also, although the CO<sub>2</sub> adsorption capacity on SrETS-4-110 decreased by less than 35% compared to ETS-4 at the same activation temperature(110&#xa0;°C), CO<sub>2</sub>/CH<sub>4</sub> and CO<sub>2</sub>/N<sub>2</sub> selectivities increased up to 1951 and 1088 which was an increase of 46% and 150%, respectively while the kinetic rate constant of the PNO model (k<sub>n</sub>) increased from 30.7 to 33.5. In addition, by increasing activation temperature to 210&#xa0;°C for Sr-exchanged samples (SrETS-4-210), the lowest selectivity value was achieved for CO<sub>2</sub>/CH<sub>4</sub> (267) and CO<sub>2</sub>/N<sub>2</sub> (229). Furthermore, the regeneration performance of ETS-4 and the Sr-exchanged ETS-4 after CO<sub>2</sub> adsorption was investigated for the first time using different regeneration methods including pressure reduction, applying vacuum, and heating. It was observed that the regeneration efficiency of SrETS-4-110 increased from 68 to 85% in comparison to ETS-4 by applying vacuum, but for SrETS-4-210, this value decreased to 72%. In conclusion, SrETS-4-110 with an enhanced thermal stability and good adsorption properties, the highest selectivity as well as the highest regeneration efficiency can be suggested to use in PSA-based CO<sub>2</sub> separation.</p>

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Investigation of ETS-4 ion exchanged with strontium and the effect of activation temperature on adsorption equilibrium, kinetics and regeneration in CO2 capture from natural gas and post-combustion gas mixtures

  • 期刊论文

  • 发表日期：

    2026年7月3日

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  • Amirhossein Khademi,
  • Ensieh Ganji Babakhani,
  • Jafar Towfighi Darian,
  • Ramin Ebrahimi,
  • Mahnaz Pourkhalil

摘要

ETS-4 titanosilicate adsorbent with unique characteristics is very suitable for CO2 adsorption. However, it is still necessary to study the adsorption performance details and regeneration performance of this adsorbent as well as its ion-exchange type Sr-ETS-4 and the effect of the activation temperature for CO2/CH4 separation and post-combustion CO2 capture (CO2/N2 separation). In the present work, CO2, CH4, and N2 adsorption equilibria for the synthesized ETS-4 and Sr-exchanged ETS-4 were measured at 25 °C. Adsorption data were used for modeling to predict the phase diagram, selectivity, and total adsorption of samples in binary mixtures with the IAST method. Also, the CO2 adsorption kinetics data were measured and investigated by micropore diffusion and Pseudo-nth-Order (PNO) models. The results showed that ion exchange with strontium enhanced significantly the thermal stability of ETS-4. Also, although the CO2 adsorption capacity on SrETS-4-110 decreased by less than 35% compared to ETS-4 at the same activation temperature(110 °C), CO2/CH4 and CO2/N2 selectivities increased up to 1951 and 1088 which was an increase of 46% and 150%, respectively while the kinetic rate constant of the PNO model (kn) increased from 30.7 to 33.5. In addition, by increasing activation temperature to 210 °C for Sr-exchanged samples (SrETS-4-210), the lowest selectivity value was achieved for CO2/CH4 (267) and CO2/N2 (229). Furthermore, the regeneration performance of ETS-4 and the Sr-exchanged ETS-4 after CO2 adsorption was investigated for the first time using different regeneration methods including pressure reduction, applying vacuum, and heating. It was observed that the regeneration efficiency of SrETS-4-110 increased from 68 to 85% in comparison to ETS-4 by applying vacuum, but for SrETS-4-210, this value decreased to 72%. In conclusion, SrETS-4-110 with an enhanced thermal stability and good adsorption properties, the highest selectivity as well as the highest regeneration efficiency can be suggested to use in PSA-based CO2 separation.