Kinetic isotope effect for H-2 and D-2 quantum molecular sieving in adsorption/desorption on porous carbon materials

Xuebo Zhao, Silvia Villar-Rodil, Ashleigh J. Fletcher, K. Mark Thomas

Research output: Contribution to journalArticle

103 Citations (Scopus)

Abstract

Adsorption and desorption of H-2 and D-2 from porous carbon materials, such as activated carbon at 77 K, are usually fully reversible with very rapid adsorption/desorption kinetics. The adsorption and desorption of H-2 and D-2 at 77 K on a carbon molecular sieve (Takeda 3A), where the kinetic selectivity was incorporated by carbon deposition, and a carbon, where the pore structure was modified by thermal annealing to give similar pore structure characteristics to the carbon molecular sieve substrate, were studied. The D-2 adsorption and desorption kinetics were significantly faster ( up to x 1.9) than the corresponding H-2 kinetics for specific pressure increments/decrements. This represents the first experimental observation of kinetic isotope quantum molecular sieving in porous materials due to the larger zero-point energy for the lighter H-2, resulting in slower adsorption/desorption kinetics compared with the heavier D-2. The results are discussed in terms of the adsorption mechanism.
LanguageEnglish
Pages9947-9955
Number of pages8
JournalJournal of Physical Chemistry B
Volume110
Issue number20
DOIs
Publication statusPublished - 4 May 2006

Fingerprint

Isotopes
isotope effect
Desorption
Carbon
desorption
Adsorption
Kinetics
adsorption
carbon
kinetics
Molecular sieves
absorbents
Pore structure
porosity
zero point energy
porous materials
activated carbon
Activated carbon
Porous materials
isotopes

Keywords

  • Kinetic isotope
  • H-2
  • D-2
  • quantum
  • molecular
  • sieving
  • adsorption
  • desorption
  • porous
  • carbon

Cite this

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abstract = "Adsorption and desorption of H-2 and D-2 from porous carbon materials, such as activated carbon at 77 K, are usually fully reversible with very rapid adsorption/desorption kinetics. The adsorption and desorption of H-2 and D-2 at 77 K on a carbon molecular sieve (Takeda 3A), where the kinetic selectivity was incorporated by carbon deposition, and a carbon, where the pore structure was modified by thermal annealing to give similar pore structure characteristics to the carbon molecular sieve substrate, were studied. The D-2 adsorption and desorption kinetics were significantly faster ( up to x 1.9) than the corresponding H-2 kinetics for specific pressure increments/decrements. This represents the first experimental observation of kinetic isotope quantum molecular sieving in porous materials due to the larger zero-point energy for the lighter H-2, resulting in slower adsorption/desorption kinetics compared with the heavier D-2. The results are discussed in terms of the adsorption mechanism.",
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Kinetic isotope effect for H-2 and D-2 quantum molecular sieving in adsorption/desorption on porous carbon materials. / Zhao, Xuebo; Villar-Rodil, Silvia; Fletcher, Ashleigh J.; Thomas, K. Mark.

In: Journal of Physical Chemistry B, Vol. 110, No. 20, 04.05.2006, p. 9947-9955.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Kinetic isotope effect for H-2 and D-2 quantum molecular sieving in adsorption/desorption on porous carbon materials

AU - Zhao, Xuebo

AU - Villar-Rodil, Silvia

AU - Fletcher, Ashleigh J.

AU - Thomas, K. Mark

PY - 2006/5/4

Y1 - 2006/5/4

N2 - Adsorption and desorption of H-2 and D-2 from porous carbon materials, such as activated carbon at 77 K, are usually fully reversible with very rapid adsorption/desorption kinetics. The adsorption and desorption of H-2 and D-2 at 77 K on a carbon molecular sieve (Takeda 3A), where the kinetic selectivity was incorporated by carbon deposition, and a carbon, where the pore structure was modified by thermal annealing to give similar pore structure characteristics to the carbon molecular sieve substrate, were studied. The D-2 adsorption and desorption kinetics were significantly faster ( up to x 1.9) than the corresponding H-2 kinetics for specific pressure increments/decrements. This represents the first experimental observation of kinetic isotope quantum molecular sieving in porous materials due to the larger zero-point energy for the lighter H-2, resulting in slower adsorption/desorption kinetics compared with the heavier D-2. The results are discussed in terms of the adsorption mechanism.

AB - Adsorption and desorption of H-2 and D-2 from porous carbon materials, such as activated carbon at 77 K, are usually fully reversible with very rapid adsorption/desorption kinetics. The adsorption and desorption of H-2 and D-2 at 77 K on a carbon molecular sieve (Takeda 3A), where the kinetic selectivity was incorporated by carbon deposition, and a carbon, where the pore structure was modified by thermal annealing to give similar pore structure characteristics to the carbon molecular sieve substrate, were studied. The D-2 adsorption and desorption kinetics were significantly faster ( up to x 1.9) than the corresponding H-2 kinetics for specific pressure increments/decrements. This represents the first experimental observation of kinetic isotope quantum molecular sieving in porous materials due to the larger zero-point energy for the lighter H-2, resulting in slower adsorption/desorption kinetics compared with the heavier D-2. The results are discussed in terms of the adsorption mechanism.

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KW - H-2

KW - D-2

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KW - molecular

KW - sieving

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