Effect of time, temperature, and kinetics on the hysteretic adsorption-desorption of H 2, Ar, and N 2 in the metal-organic framework Zn 2(bpdc) 2(bpee)

Sarmishtha Sircar, Haohan Wu, Jing Li, Angela D. Lueking

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

The intriguing hysteretic adsorption-desorption behavior of certain microporous metal-organic frameworks (MMOFs) has received considerable attention and is often associated with a gate-opening (GO) effect. Here, the hysteretic adsorption of N 2 and Ar to Zn 2(bpdc) 2(bpee) (bpdc = 4,4′-biphenyldicarboxylate; bpee = 1,2-bipyridylethene) shows a pronounced effect of allowed experimental time at 77 and 87 K. When the time allowed is on the order of minutes for N 2 at 77 K, no adsorption is observed, whereas times in excess of 60 h is required to achieve appreciable adsorption up to a limiting total coverage. Given sufficient time, the total uptake for N 2 and Ar converged at similar reduced temperatures, but the adsorption of Ar was significantly more rapid than that of N 2, an observation that can be described by activated configurational diffusion. N 2 and Ar both exhibited discontinuous stepped adsorption isotherms with significant hysteresis, features that were dependent upon the allowed time. The uptake of H 2 at 77 K was greater than for both N 2 and Ar but showed no discontinuity in the isotherm, and hysteretic effects were much less pronounced. N 2 and Ar adsorption data can be described by an activated diffusion process, with characteristic times leading to activation energies of 6.7 and 12 kJ/mol. Fits of H 2 adsorption data led to activation energies in the range 2-7 kJ/mol at low coverage and nonactivated diffusion at higher coverage. An alternate concentration-dependent diffusion model is presented to describe the stepwise adsorption behavior, which is observed for N 2 and Ar but not for H 2. Equilibrium is approached very slowly for adsorption to molecularly sized pores at low temperature, and structural change (gate opening), although it may occur, is not required to explain the observations.

Original languageEnglish
Pages (from-to)14169-14179
Number of pages11
JournalLangmuir
Volume27
Issue number23
DOIs
Publication statusPublished - Dec 6 2011

Fingerprint

Desorption
Metals
desorption
Adsorption
Kinetics
adsorption
kinetics
metals
gates (openings)
Temperature
temperature
Activation energy
isotherms
activation energy
Adsorption isotherms
Isotherms
Hysteresis
discontinuity
hysteresis
porosity

ASJC Scopus subject areas

  • Electrochemistry
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Materials Science(all)
  • Spectroscopy

Cite this

Effect of time, temperature, and kinetics on the hysteretic adsorption-desorption of H 2, Ar, and N 2 in the metal-organic framework Zn 2(bpdc) 2(bpee). / Sircar, Sarmishtha; Wu, Haohan; Li, Jing; Lueking, Angela D.

In: Langmuir, Vol. 27, No. 23, 06.12.2011, p. 14169-14179.

Research output: Contribution to journalArticle

@article{83ad01109dcd42ea8befc62bf6392de5,
title = "Effect of time, temperature, and kinetics on the hysteretic adsorption-desorption of H 2, Ar, and N 2 in the metal-organic framework Zn 2(bpdc) 2(bpee)",
abstract = "The intriguing hysteretic adsorption-desorption behavior of certain microporous metal-organic frameworks (MMOFs) has received considerable attention and is often associated with a gate-opening (GO) effect. Here, the hysteretic adsorption of N 2 and Ar to Zn 2(bpdc) 2(bpee) (bpdc = 4,4′-biphenyldicarboxylate; bpee = 1,2-bipyridylethene) shows a pronounced effect of allowed experimental time at 77 and 87 K. When the time allowed is on the order of minutes for N 2 at 77 K, no adsorption is observed, whereas times in excess of 60 h is required to achieve appreciable adsorption up to a limiting total coverage. Given sufficient time, the total uptake for N 2 and Ar converged at similar reduced temperatures, but the adsorption of Ar was significantly more rapid than that of N 2, an observation that can be described by activated configurational diffusion. N 2 and Ar both exhibited discontinuous stepped adsorption isotherms with significant hysteresis, features that were dependent upon the allowed time. The uptake of H 2 at 77 K was greater than for both N 2 and Ar but showed no discontinuity in the isotherm, and hysteretic effects were much less pronounced. N 2 and Ar adsorption data can be described by an activated diffusion process, with characteristic times leading to activation energies of 6.7 and 12 kJ/mol. Fits of H 2 adsorption data led to activation energies in the range 2-7 kJ/mol at low coverage and nonactivated diffusion at higher coverage. An alternate concentration-dependent diffusion model is presented to describe the stepwise adsorption behavior, which is observed for N 2 and Ar but not for H 2. Equilibrium is approached very slowly for adsorption to molecularly sized pores at low temperature, and structural change (gate opening), although it may occur, is not required to explain the observations.",
author = "Sarmishtha Sircar and Haohan Wu and Jing Li and Lueking, {Angela D.}",
year = "2011",
month = "12",
day = "6",
doi = "10.1021/la202842m",
language = "English",
volume = "27",
pages = "14169--14179",
journal = "Langmuir",
issn = "0743-7463",
publisher = "American Chemical Society",
number = "23",

}

TY - JOUR

T1 - Effect of time, temperature, and kinetics on the hysteretic adsorption-desorption of H 2, Ar, and N 2 in the metal-organic framework Zn 2(bpdc) 2(bpee)

AU - Sircar, Sarmishtha

AU - Wu, Haohan

AU - Li, Jing

AU - Lueking, Angela D.

PY - 2011/12/6

Y1 - 2011/12/6

N2 - The intriguing hysteretic adsorption-desorption behavior of certain microporous metal-organic frameworks (MMOFs) has received considerable attention and is often associated with a gate-opening (GO) effect. Here, the hysteretic adsorption of N 2 and Ar to Zn 2(bpdc) 2(bpee) (bpdc = 4,4′-biphenyldicarboxylate; bpee = 1,2-bipyridylethene) shows a pronounced effect of allowed experimental time at 77 and 87 K. When the time allowed is on the order of minutes for N 2 at 77 K, no adsorption is observed, whereas times in excess of 60 h is required to achieve appreciable adsorption up to a limiting total coverage. Given sufficient time, the total uptake for N 2 and Ar converged at similar reduced temperatures, but the adsorption of Ar was significantly more rapid than that of N 2, an observation that can be described by activated configurational diffusion. N 2 and Ar both exhibited discontinuous stepped adsorption isotherms with significant hysteresis, features that were dependent upon the allowed time. The uptake of H 2 at 77 K was greater than for both N 2 and Ar but showed no discontinuity in the isotherm, and hysteretic effects were much less pronounced. N 2 and Ar adsorption data can be described by an activated diffusion process, with characteristic times leading to activation energies of 6.7 and 12 kJ/mol. Fits of H 2 adsorption data led to activation energies in the range 2-7 kJ/mol at low coverage and nonactivated diffusion at higher coverage. An alternate concentration-dependent diffusion model is presented to describe the stepwise adsorption behavior, which is observed for N 2 and Ar but not for H 2. Equilibrium is approached very slowly for adsorption to molecularly sized pores at low temperature, and structural change (gate opening), although it may occur, is not required to explain the observations.

AB - The intriguing hysteretic adsorption-desorption behavior of certain microporous metal-organic frameworks (MMOFs) has received considerable attention and is often associated with a gate-opening (GO) effect. Here, the hysteretic adsorption of N 2 and Ar to Zn 2(bpdc) 2(bpee) (bpdc = 4,4′-biphenyldicarboxylate; bpee = 1,2-bipyridylethene) shows a pronounced effect of allowed experimental time at 77 and 87 K. When the time allowed is on the order of minutes for N 2 at 77 K, no adsorption is observed, whereas times in excess of 60 h is required to achieve appreciable adsorption up to a limiting total coverage. Given sufficient time, the total uptake for N 2 and Ar converged at similar reduced temperatures, but the adsorption of Ar was significantly more rapid than that of N 2, an observation that can be described by activated configurational diffusion. N 2 and Ar both exhibited discontinuous stepped adsorption isotherms with significant hysteresis, features that were dependent upon the allowed time. The uptake of H 2 at 77 K was greater than for both N 2 and Ar but showed no discontinuity in the isotherm, and hysteretic effects were much less pronounced. N 2 and Ar adsorption data can be described by an activated diffusion process, with characteristic times leading to activation energies of 6.7 and 12 kJ/mol. Fits of H 2 adsorption data led to activation energies in the range 2-7 kJ/mol at low coverage and nonactivated diffusion at higher coverage. An alternate concentration-dependent diffusion model is presented to describe the stepwise adsorption behavior, which is observed for N 2 and Ar but not for H 2. Equilibrium is approached very slowly for adsorption to molecularly sized pores at low temperature, and structural change (gate opening), although it may occur, is not required to explain the observations.

UR - http://www.scopus.com/inward/record.url?scp=82455191791&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=82455191791&partnerID=8YFLogxK

U2 - 10.1021/la202842m

DO - 10.1021/la202842m

M3 - Article

VL - 27

SP - 14169

EP - 14179

JO - Langmuir

JF - Langmuir

SN - 0743-7463

IS - 23

ER -