Grand Canonical Monte Carlo studies of CO2 and CH4 adsorption in p-tert-butylcalix[4]arene
Grand Canonical Monte Carlo (GCMC) simulations were performed for single component isotherms of CO2 and CH4 in the p-tert-butylcalix[4]arene (TBC4) structure. Comparison with literature data for adsorption used the Peng-Robinson equation of state to map simulated fugacities to experimentally determined pressures. CO2 binding in the high-pressure structure of TBC4 (TBC4-H) occurs in two distinct waves. The cage sites in TBC4 completely fill, followed by the filling of interstitial sites, resulting in the sum of two Langmuir isotherms being the best way to describe the total absorption isotherms. Our simulation results capture the essential experimental feature that the cage sites are the major contributor to the absorption isotherms, and the contribution of interstitial sites are significantly less. We found that CH4 does not exhibit the same two site binding characteristic and has a smaller temperature dependence, which arises from a smaller negative entropy change upon absorption compared with CO2. Our calculations give higher binding than observed experimentally for the cage site but lower binding for the interstitial site. We also demonstrate that by rescaling the interaction between CO2 and the lattice, the results can reproduce the experimental data well. This work was performed at the Pacific Northwest National Laboratory (PNNL) and was supported by the Division of Chemical Sciences, Office of Basic Energy Sciences, U.S. Department of Energy (DOE). PNNL is operated by Battelle for the DOE.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 982290
- Report Number(s):
- PNNL-SA-67808; ISSN 1520-5207; KC0301020; TRN: US201013%%970
- Journal Information:
- Journal of Physical Chemistry B, 114(17):5764-5768, Vol. 114, Issue 17; ISSN 1520-6106
- Country of Publication:
- United States
- Language:
- English
Similar Records
Free energies of CO2/H-2 capture by p-tert-butylcalix[4]arene. A molecular dynamics study
Computational studies of load-dependent guest dynamics and free energies of inclusion for CO2 in low-density p-tert-butylcalix[4]arene at loadings up to 2:1