Characterization of kinetic limitations to atmospheric CO2 capture by solid sorbent

Tao Wang, Jun Liu, Klaus Lackner, Xiaoyang Shi, Mengxiang Fang, Zhongyang Luo

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


Scrubbing CO2 directly from the ambient air (air capture) by sorbent is an emerging technology to address climate change due to anthropic emission of greenhouse gases. A good understanding of thermodynamics and reaction kinetics under ultra-low CO2 concentration and variable humidity is fundamental to the design of economic air capture. In this study, the adsorption kinetics of a novel moisture swing process for air capture is characterized. The variation of humidity alters not only the adsorption equilibrium but also the adsorption kinetics, due to a water involved chemical reaction. A heterogeneously structured sorbent sheet with strong based ion exchange resin inside as active constituent is employed to capture the atmospheric CO2 under different humidity. Traditional shrinking core model (SCM) is modified to reveal the mass transfer resistance inside of the sorbent for CO2 adsorption under ultra-low CO2 concentration. The modified SCM reveals that, at most cases, the adsorption kinetics is controlled by diffusion inside of the sorbent particle. A transition from physical diffusion controlled kinetics to chemical reaction controlled kinetics is observed as humidity increases. Further kinetic analysis suggests that, among the optimization technologies such as seeking functional group with faster chemical reaction or fabricating thinner support layer, preparing sorbent particle with smaller size or higher porosity should have much more potential on the enhancement of air capture kinetics.

Original languageEnglish (US)
Pages (from-to)138-149
Number of pages12
JournalGreenhouse Gases: Science and Technology
Issue number1
StatePublished - Feb 1 2016


  • CO air capture
  • adsorption kinetics
  • mass transfer resistance
  • moisture swing adsorption
  • shrinking core model
  • sorbent optimization

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry


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