Adsorption

, Volume 19, Issue 2, pp 643–652

Supercritical hydrogen adsorption in nanostructured solids with hydrogen density variation in pores

  • Jessica E. Sharpe
  • Nuno Bimbo
  • Valeska P. Ting
  • Andrew D. Burrows
  • Dongmei Jiang
  • Timothy J. Mays
Article

DOI: 10.1007/s10450-013-9487-6

Cite this article as:
Sharpe, J.E., Bimbo, N., Ting, V.P. et al. Adsorption (2013) 19: 643. doi:10.1007/s10450-013-9487-6

Abstract

Experimental excess isotherms for the adsorption of gases in porous solids may be represented by mathematical models that incorporate the total amount of gas within a pore, a quantity which cannot easily be found experimentally but which is important for calculations for many applications, including adsorptive storage. A model that is currently used for hydrogen adsorption in porous solids has been improved to include a more realistic density profile of the gas within the pore, and allows calculation of the total amount of adsorbent. A comparison has been made between different Type I isotherm equations embedded in the model, by examining the quality of the fits to hydrogen isotherms for six different nanoporous materials. A new Type I isotherm equation which has not previously been reported in the literature, the Unilan-b equation, has been derived and has also been included in this comparison study. These results indicate that while some Type I isotherm equations fit certain types of materials better than others, the Tόth equation produces the best overall quality of fit and also provides realistic parameter values when used to analyse hydrogen sorption data for a model carbon adsorbent.

Keywords

Hydrogen adsorptionPorous solidsIsotherm equations

List of symbols

MOF

Metal–organic framework

PIM

Polymer of intrinsic microporosity

mE

Excess mass of hydrogen

vP

Pore volume

ρB

Bulk density

mAmax

Limiting maximum uptake

θA

Fractional filling

wt %

Weight percent

P

Absolute pressure

b

Affinity parameter

Q

Enthalpic factor

b0

Pre-exponential factor

R

Molar gas constant

T

Absolute temperature

bdc

Benzene-1,4-dicarboxylate

MIL

Matériaux de l’Institut Lavoisier

BET

Brunauer, Emmett and Teller

mB(A)

Bulk hydrogen within the adsorbate

mA

Absolute uptake

mP

Total uptake

ρA

Adsorbate density

vA

Adsorbate volume

M

Molar mass

Z

Compressibility factor

NIST

National Institute of Standards and Technology

b(T)

Tόth affinity parameter

c(T)

Tόth heterogeneity parameter

RMSR

Root mean square residual

b1

Minimum value of b in a uniform distribution

b2

Maximum value of b in a uniform distribution

Q1

Minimum value of Q in a uniform distribution

Q2

Maximum value of Q in a uniform distribution

θ(P,h)

Local isotherm

h

Heterogeneity parameter

w

Substitution variable

b(L)

Langmuir affinity parameter

b(S)

Sips affinity parameter

m(S)

Sips heterogeneity parameter

b(GF)

Generalised Freundlich affinity parameter

q

Generalised Freundlich heterogeneity parameter

b(JF)

Jovanović–Freundlich affinity parameter

c(JF)

Jovanović–Freundlich heterogeneity parameter

α

Dubinin–Astakhov enthalpic factor

β

Dubinin–Astakhov entropic factor

m(DA)

Adjustable parameter within the Dubinin–Astakhov equation

P0

Vapour pressure

GCMC

Grand-canonical Monte Carlo

Supplementary material

10450_2013_9487_MOESM1_ESM.docx (2.7 mb)
Supplementary material 1 (DOCX 2720 kb)

Copyright information

© Springer Science+Business Media New York 2013

Authors and Affiliations

  • Jessica E. Sharpe
    • 1
  • Nuno Bimbo
    • 2
  • Valeska P. Ting
    • 2
  • Andrew D. Burrows
    • 3
  • Dongmei Jiang
    • 3
  • Timothy J. Mays
    • 2
  1. 1.Department of Chemical Engineering, EPSRC Doctoral Training Centre, Centre for Sustainable Chemical TechnologiesUniversity of BathBathUK
  2. 2.Department of Chemical EngineeringUniversity of BathBathUK
  3. 3.Department of ChemistryUniversity of BathBathUK