caa a22 4500 463170113 CHVBK 20180406164810.0 cr unu---uuuuu 170326e20070801xx s 000 0 eng 10.1007/s10450-007-9061-1 doi (NATIONALLICENCE)springer-10.1007/s10450-007-9061-1 Pore accessibility of N2 and Ar in disordered nanoporous solids: theory and experiment [Elektronische Daten] [T. Nguyen, S. Bhatia] Recently (Nguyen and Bhatia, J.Phys. Chem. C 111:2212-2222, 2007) we have proposed a new algorithm utilising cluster analysis principles to determine pore network accessibility of a disordered material. The algorithm was applied to determine pore accessibility of the reconstructed molecular structure of a saccharose char, obtained in our recent work using hybrid reverse Monte Carlo simulation (Nguyen et al., Mol. Simul. 32:567-577, 2006). The method also identifies kinetically closed pores not accessed by adsorbate molecules at low temperature, when their low kinetic energy cannot overcome the potential barrier at the mouths of pores that can otherwise accommodate them. In the current work, the results are validated by transition state theory calculations for N2 and Ar adsorption, showing that N2 can equilibrate in narrow micropores at practical time scales at 300K, but not at 77K. Large differences between time scales for micropore entry and exit are predicted at low temperature for N2, the latter being smaller by over three orders of magnitude. For N2 at 77K the time constant for pore entry exceeds 3hr., while for exit it is 134 days. At 300 K these values are smaller than 1 μs, indicating good accessibility at this temperature. These results are verified by molecular dynamics simulations, which reveal that while N2 molecules enter and leave all pores frequently at 300K, entry and exit events for apparently inaccessible pores are absent at 77K. For Ar at 87K better accessibility is evident for the saccharose char compared to N2 at 77K. This finding is now experimentally shown in this work by comparison of pore size distributions obtained from experimental nitrogen adsorption isotherms of nitrogen and argon at 77K and87K. Springer Science+Business Media, LLC, 2007 Gas phase adsorption nationallicence Molecular modeling nationallicence Pore accessibility nationallicence Transition state theory nationallicence Nguyen T. Division of Chemical Engineering, The University of Queensland, 4072, Brisbane, QLD, Australia aut Bhatia S. Division of Chemical Engineering, The University of Queensland, 4072, Brisbane, QLD, Australia aut Adsorption Springer US; http://www.springer-ny.com 13/3-4(2007-08-01), 307-314 0929-5607 13:3-4<307 2007 13 10450 https://doi.org/10.1007/s10450-007-9061-1 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10450-007-9061-1 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Nguyen T. Division of Chemical Engineering, The University of Queensland, 4072, Brisbane, QLD, Australia aut NATIONALLICENCE 700 1- Bhatia S. Division of Chemical Engineering, The University of Queensland, 4072, Brisbane, QLD, Australia aut NATIONALLICENCE 773 0- Adsorption Springer US; http://www.springer-ny.com 13/3-4(2007-08-01), 307-314 0929-5607 13:3-4<307 2007 13 10450 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer