Thermodynamic evidence of flexibility in H2O and CO2 absorption of transition metal ion exchanged zeolite LTA

Xin Guo, Lili Wu, Alexandra Navrotsky

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Gas absorption calorimetry has been employed to probe the intercation of water and carbon dioxide with transition metal ion (TM = Mn2+, Fe2+, Co2+, Cu2+, and Zn2+) exchanged zeolite A samples. There appears to be a two-phase region, indicative of a guest-induced flexibility transition, separating hydrated zeolite A and its dehydrated form, both of which have variable water content in the single phase region. The differential enthalpy of absorption as a function of water loading directly identifies different strengths of multiple interactions along with possible binding mechanisms of Zn-A and Mn-A exhibiting the highest water absorption with most exothermic initial enthalpies of -125.28 ± 4.82 and -115.30 ± 2.56 kJ mol-1. Zn-A and Mn-A also show moderately good capture ability for CO2 with zero-coverage negative enthalpies of -55.59 ± 2.48 and -44.07 ± 1.53 kJ mol-1. The thermodynamic information derived from differential enthalpy, chemical potential and differential entropy elucidated the multistage interactive behavior of small guest molecules (H2O/CO2) and ion-exchanged frameworks.

Original languageEnglish (US)
Pages (from-to)3970-3978
Number of pages9
JournalPhysical Chemistry Chemical Physics
Issue number6
StatePublished - 2018
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry


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