Thermal structural transitions and carbon dioxide adsorption properties of zeolitic imidazolate framework-7 (ZIF-7)

Wanxi Cai, Taehee Lee, Maro Lee, Woosuk Cho, Doug Young Han, Nakwon Choi, Alex C K Yip, Jungkyu Choi

Research output: Contribution to journalArticle

47 Citations (Scopus)

Abstract

As a subset of the metal-organic frameworks, zeolitic imidazolate frameworks (ZIFs) have potential use in practical separations as a result of flexible yet reliable control over their pore sizes along with their chemical and thermal stabilities. Among many ZIF materials, we explored the effect of thermal treatments on the ZIF-7 structure, known for its promising characteristics toward H2 separations; the pore sizes of ZIF-7 (0.29 nm) are desirable for molecular sieving, favoring H2 (0.289 nm) over CO2 (0.33 nm). Although thermogravimetric analysis indicated that ZIF-7 is thermally stabile up to ∼400 °C, the structural transition of ZIF-7 to an intermediate phase (as indicated by X-ray analysis) was observed under air as guest molecules were removed. The transition was further continued at higher temperatures, eventually leading toward the zinc oxide phase. Three types of ZIF-7 with differing shapes and sizes (∼100 nm spherical, ∼400 nm rhombic-dodecahedral, and ∼1300 nm rod-shaped) were employed to elucidate (1) thermal structural transitions while considering kinetically relevant processes and (2) discrepancies in the N2 physisorption and CO 2 adsorption isotherms. The largest rod-shaped ZIF-7 particles showed a delayed thermal structural transition toward the stable zinc oxide phase. The CO2 adsorption behaviors of the three ZIF-7s, despite their identical crystal structures, suggested minute differences in the pore structures; in particular, the smaller spherical ZIF-7 particles provided reversible CO2 adsorption isotherms at ∼30-75 °C, a typical temperature range of flue gases from coal-fired power plants, in contrast to the larger rhombic-dodecahedral and rod-shaped ZIF-7 particles, which exhibited hysteretic CO2 adsorption/desorption behavior.

Original languageEnglish
Pages (from-to)7961-7971
Number of pages11
JournalJournal of the American Chemical Society
Volume136
Issue number22
DOIs
Publication statusPublished - 2014 Jun 4

Fingerprint

Zinc Oxide
Zinc oxide
Adsorption isotherms
Carbon Dioxide
Adsorption
Pore size
Carbon dioxide
Hot Temperature
Physisorption
Coal
Chemical stability
X ray analysis
Carbon Monoxide
Pore structure
Flue gases
Thermogravimetric analysis
Desorption
Power plants
Thermodynamic stability
Crystal structure

ASJC Scopus subject areas

  • Chemistry(all)
  • Catalysis
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Thermal structural transitions and carbon dioxide adsorption properties of zeolitic imidazolate framework-7 (ZIF-7). / Cai, Wanxi; Lee, Taehee; Lee, Maro; Cho, Woosuk; Han, Doug Young; Choi, Nakwon; Yip, Alex C K; Choi, Jungkyu.

In: Journal of the American Chemical Society, Vol. 136, No. 22, 04.06.2014, p. 7961-7971.

Research output: Contribution to journalArticle

Cai, Wanxi ; Lee, Taehee ; Lee, Maro ; Cho, Woosuk ; Han, Doug Young ; Choi, Nakwon ; Yip, Alex C K ; Choi, Jungkyu. / Thermal structural transitions and carbon dioxide adsorption properties of zeolitic imidazolate framework-7 (ZIF-7). In: Journal of the American Chemical Society. 2014 ; Vol. 136, No. 22. pp. 7961-7971.
@article{a7d3121dd698475599660c0be615de5e,
title = "Thermal structural transitions and carbon dioxide adsorption properties of zeolitic imidazolate framework-7 (ZIF-7)",
abstract = "As a subset of the metal-organic frameworks, zeolitic imidazolate frameworks (ZIFs) have potential use in practical separations as a result of flexible yet reliable control over their pore sizes along with their chemical and thermal stabilities. Among many ZIF materials, we explored the effect of thermal treatments on the ZIF-7 structure, known for its promising characteristics toward H2 separations; the pore sizes of ZIF-7 (0.29 nm) are desirable for molecular sieving, favoring H2 (0.289 nm) over CO2 (0.33 nm). Although thermogravimetric analysis indicated that ZIF-7 is thermally stabile up to ∼400 °C, the structural transition of ZIF-7 to an intermediate phase (as indicated by X-ray analysis) was observed under air as guest molecules were removed. The transition was further continued at higher temperatures, eventually leading toward the zinc oxide phase. Three types of ZIF-7 with differing shapes and sizes (∼100 nm spherical, ∼400 nm rhombic-dodecahedral, and ∼1300 nm rod-shaped) were employed to elucidate (1) thermal structural transitions while considering kinetically relevant processes and (2) discrepancies in the N2 physisorption and CO 2 adsorption isotherms. The largest rod-shaped ZIF-7 particles showed a delayed thermal structural transition toward the stable zinc oxide phase. The CO2 adsorption behaviors of the three ZIF-7s, despite their identical crystal structures, suggested minute differences in the pore structures; in particular, the smaller spherical ZIF-7 particles provided reversible CO2 adsorption isotherms at ∼30-75 °C, a typical temperature range of flue gases from coal-fired power plants, in contrast to the larger rhombic-dodecahedral and rod-shaped ZIF-7 particles, which exhibited hysteretic CO2 adsorption/desorption behavior.",
author = "Wanxi Cai and Taehee Lee and Maro Lee and Woosuk Cho and Han, {Doug Young} and Nakwon Choi and Yip, {Alex C K} and Jungkyu Choi",
year = "2014",
month = "6",
day = "4",
doi = "10.1021/ja5016298",
language = "English",
volume = "136",
pages = "7961--7971",
journal = "Journal of the American Chemical Society",
issn = "0002-7863",
publisher = "American Chemical Society",
number = "22",

}

TY - JOUR

T1 - Thermal structural transitions and carbon dioxide adsorption properties of zeolitic imidazolate framework-7 (ZIF-7)

AU - Cai, Wanxi

AU - Lee, Taehee

AU - Lee, Maro

AU - Cho, Woosuk

AU - Han, Doug Young

AU - Choi, Nakwon

AU - Yip, Alex C K

AU - Choi, Jungkyu

PY - 2014/6/4

Y1 - 2014/6/4

N2 - As a subset of the metal-organic frameworks, zeolitic imidazolate frameworks (ZIFs) have potential use in practical separations as a result of flexible yet reliable control over their pore sizes along with their chemical and thermal stabilities. Among many ZIF materials, we explored the effect of thermal treatments on the ZIF-7 structure, known for its promising characteristics toward H2 separations; the pore sizes of ZIF-7 (0.29 nm) are desirable for molecular sieving, favoring H2 (0.289 nm) over CO2 (0.33 nm). Although thermogravimetric analysis indicated that ZIF-7 is thermally stabile up to ∼400 °C, the structural transition of ZIF-7 to an intermediate phase (as indicated by X-ray analysis) was observed under air as guest molecules were removed. The transition was further continued at higher temperatures, eventually leading toward the zinc oxide phase. Three types of ZIF-7 with differing shapes and sizes (∼100 nm spherical, ∼400 nm rhombic-dodecahedral, and ∼1300 nm rod-shaped) were employed to elucidate (1) thermal structural transitions while considering kinetically relevant processes and (2) discrepancies in the N2 physisorption and CO 2 adsorption isotherms. The largest rod-shaped ZIF-7 particles showed a delayed thermal structural transition toward the stable zinc oxide phase. The CO2 adsorption behaviors of the three ZIF-7s, despite their identical crystal structures, suggested minute differences in the pore structures; in particular, the smaller spherical ZIF-7 particles provided reversible CO2 adsorption isotherms at ∼30-75 °C, a typical temperature range of flue gases from coal-fired power plants, in contrast to the larger rhombic-dodecahedral and rod-shaped ZIF-7 particles, which exhibited hysteretic CO2 adsorption/desorption behavior.

AB - As a subset of the metal-organic frameworks, zeolitic imidazolate frameworks (ZIFs) have potential use in practical separations as a result of flexible yet reliable control over their pore sizes along with their chemical and thermal stabilities. Among many ZIF materials, we explored the effect of thermal treatments on the ZIF-7 structure, known for its promising characteristics toward H2 separations; the pore sizes of ZIF-7 (0.29 nm) are desirable for molecular sieving, favoring H2 (0.289 nm) over CO2 (0.33 nm). Although thermogravimetric analysis indicated that ZIF-7 is thermally stabile up to ∼400 °C, the structural transition of ZIF-7 to an intermediate phase (as indicated by X-ray analysis) was observed under air as guest molecules were removed. The transition was further continued at higher temperatures, eventually leading toward the zinc oxide phase. Three types of ZIF-7 with differing shapes and sizes (∼100 nm spherical, ∼400 nm rhombic-dodecahedral, and ∼1300 nm rod-shaped) were employed to elucidate (1) thermal structural transitions while considering kinetically relevant processes and (2) discrepancies in the N2 physisorption and CO 2 adsorption isotherms. The largest rod-shaped ZIF-7 particles showed a delayed thermal structural transition toward the stable zinc oxide phase. The CO2 adsorption behaviors of the three ZIF-7s, despite their identical crystal structures, suggested minute differences in the pore structures; in particular, the smaller spherical ZIF-7 particles provided reversible CO2 adsorption isotherms at ∼30-75 °C, a typical temperature range of flue gases from coal-fired power plants, in contrast to the larger rhombic-dodecahedral and rod-shaped ZIF-7 particles, which exhibited hysteretic CO2 adsorption/desorption behavior.

UR - http://www.scopus.com/inward/record.url?scp=84901916298&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84901916298&partnerID=8YFLogxK

U2 - 10.1021/ja5016298

DO - 10.1021/ja5016298

M3 - Article

C2 - 24813064

AN - SCOPUS:84901916298

VL - 136

SP - 7961

EP - 7971

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

SN - 0002-7863

IS - 22

ER -