Competitive reactions during synthesis of zinc aluminum layered double hydroxides by thermal hydrolysis of urea

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Competitive reactions during synthesis of zinc aluminum layered double hydroxides by thermal hydrolysis of urea. / Staal, Line Boisen; Pushparaj, Suraj Shiv Charan; Forano, Claude; Prevot, Vanessa; Ravnsbaek, Dorthe Bomholdt; Bjerring, Morten; Nielsen, Ulla Gro.

In: Journal of Materials Chemistry A, Vol. 5, No. 41, 07.11.2017, p. 21795-21806.

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaperJournal articleResearchpeer-review

Harvard

Staal, LB, Pushparaj, SSC, Forano, C, Prevot, V, Ravnsbaek, DB, Bjerring, M & Nielsen, UG 2017, 'Competitive reactions during synthesis of zinc aluminum layered double hydroxides by thermal hydrolysis of urea', Journal of Materials Chemistry A, vol. 5, no. 41, pp. 21795-21806. https://doi.org/10.1039/c7ta05761j

APA

Staal, L. B., Pushparaj, S. S. C., Forano, C., Prevot, V., Ravnsbaek, D. B., Bjerring, M., & Nielsen, U. G. (2017). Competitive reactions during synthesis of zinc aluminum layered double hydroxides by thermal hydrolysis of urea. Journal of Materials Chemistry A, 5(41), 21795-21806. https://doi.org/10.1039/c7ta05761j

CBE

Staal LB, Pushparaj SSC, Forano C, Prevot V, Ravnsbaek DB, Bjerring M, Nielsen UG. 2017. Competitive reactions during synthesis of zinc aluminum layered double hydroxides by thermal hydrolysis of urea. Journal of Materials Chemistry A. 5(41):21795-21806. https://doi.org/10.1039/c7ta05761j

MLA

Vancouver

Staal LB, Pushparaj SSC, Forano C, Prevot V, Ravnsbaek DB, Bjerring M et al. Competitive reactions during synthesis of zinc aluminum layered double hydroxides by thermal hydrolysis of urea. Journal of Materials Chemistry A. 2017 Nov 7;5(41):21795-21806. https://doi.org/10.1039/c7ta05761j

Author

Staal, Line Boisen ; Pushparaj, Suraj Shiv Charan ; Forano, Claude ; Prevot, Vanessa ; Ravnsbaek, Dorthe Bomholdt ; Bjerring, Morten ; Nielsen, Ulla Gro. / Competitive reactions during synthesis of zinc aluminum layered double hydroxides by thermal hydrolysis of urea. In: Journal of Materials Chemistry A. 2017 ; Vol. 5, No. 41. pp. 21795-21806.

Bibtex

@article{7e1caa6a58bd45b88dcc529b31f6d293,
title = "Competitive reactions during synthesis of zinc aluminum layered double hydroxides by thermal hydrolysis of urea",
abstract = "Homogeneous precipitation by thermal hydrolysis of urea ({"}The urea method{"}) is preferred for the preparation of pure and highly crystalline layered double hydroxides (LDHs). However, our recent study revealed large concentrations of amorphous aluminum hydroxide (AOH) in several zinc(II) aluminum(III) LDHs (ZnAl-LDHs) prepared by this method. The origin of this AOH, the nature of an elusive zinc-rich phase, and whether phase pure LDHs can be obtained by the urea method remained unanswered [J. Phys. Chem. C., 2015, 119, 27695-27707]. Therefore, a series of ZnAl-LDHs were prepared by the urea method at four different reaction times (7, 12, 16, and 24 h) and characterized by bulk (PXRD, TEM, and elemental analysis) and local techniques (Al-27 SSNMR, FT-IR, and Raman spectroscopies) in combination with a time-resolved synchrotron PXRD study of the reaction mixture. The products obtained are a mixture of hydroxylated phases: an ill-defined aluminum hydroxide with similarities to gibbsite precipitates at 7 h, which is followed by a competitive formation of a crystalline ZnAl-LDH (approximate to 8 h) and a poorly crystalline hydrozincite during the later stages of the reaction. Their relative concentrations vary depending on the synthesis conditions, e.g., reaction time, urea/metal ratio, metal source, and hydrothermal treatment post synthesis, with less than half of the total Al3+ content incorporated in ZnAl-LDHs according to solid state Al-27 NMR. Thus, the preparation of highly crystalline and pure LDHs remains a challenge. Furthermore, these impurities will have a significant impact on application studies using LDHs prepared by the urea method.",
keywords = "HYDROTALCITE-LIKE COMPOUNDS, AL-27 NMR-SPECTROSCOPY, SOLID-STATE NMR, GAMMA-ALUMINA, STRUCTURAL-CHARACTERIZATION, CRYSTAL-STRUCTURE, NEUTRAL PH, HYDROZINCITE, STABILITY, OXIDE",
author = "Staal, {Line Boisen} and Pushparaj, {Suraj Shiv Charan} and Claude Forano and Vanessa Prevot and Ravnsbaek, {Dorthe Bomholdt} and Morten Bjerring and Nielsen, {Ulla Gro}",
year = "2017",
month = "11",
day = "7",
doi = "10.1039/c7ta05761j",
language = "English",
volume = "5",
pages = "21795--21806",
journal = "Journal of Materials Chemistry A",
issn = "2050-7488",
publisher = "ROYAL SOC CHEMISTRY",
number = "41",

}

RIS

TY - JOUR

T1 - Competitive reactions during synthesis of zinc aluminum layered double hydroxides by thermal hydrolysis of urea

AU - Staal, Line Boisen

AU - Pushparaj, Suraj Shiv Charan

AU - Forano, Claude

AU - Prevot, Vanessa

AU - Ravnsbaek, Dorthe Bomholdt

AU - Bjerring, Morten

AU - Nielsen, Ulla Gro

PY - 2017/11/7

Y1 - 2017/11/7

N2 - Homogeneous precipitation by thermal hydrolysis of urea ("The urea method") is preferred for the preparation of pure and highly crystalline layered double hydroxides (LDHs). However, our recent study revealed large concentrations of amorphous aluminum hydroxide (AOH) in several zinc(II) aluminum(III) LDHs (ZnAl-LDHs) prepared by this method. The origin of this AOH, the nature of an elusive zinc-rich phase, and whether phase pure LDHs can be obtained by the urea method remained unanswered [J. Phys. Chem. C., 2015, 119, 27695-27707]. Therefore, a series of ZnAl-LDHs were prepared by the urea method at four different reaction times (7, 12, 16, and 24 h) and characterized by bulk (PXRD, TEM, and elemental analysis) and local techniques (Al-27 SSNMR, FT-IR, and Raman spectroscopies) in combination with a time-resolved synchrotron PXRD study of the reaction mixture. The products obtained are a mixture of hydroxylated phases: an ill-defined aluminum hydroxide with similarities to gibbsite precipitates at 7 h, which is followed by a competitive formation of a crystalline ZnAl-LDH (approximate to 8 h) and a poorly crystalline hydrozincite during the later stages of the reaction. Their relative concentrations vary depending on the synthesis conditions, e.g., reaction time, urea/metal ratio, metal source, and hydrothermal treatment post synthesis, with less than half of the total Al3+ content incorporated in ZnAl-LDHs according to solid state Al-27 NMR. Thus, the preparation of highly crystalline and pure LDHs remains a challenge. Furthermore, these impurities will have a significant impact on application studies using LDHs prepared by the urea method.

AB - Homogeneous precipitation by thermal hydrolysis of urea ("The urea method") is preferred for the preparation of pure and highly crystalline layered double hydroxides (LDHs). However, our recent study revealed large concentrations of amorphous aluminum hydroxide (AOH) in several zinc(II) aluminum(III) LDHs (ZnAl-LDHs) prepared by this method. The origin of this AOH, the nature of an elusive zinc-rich phase, and whether phase pure LDHs can be obtained by the urea method remained unanswered [J. Phys. Chem. C., 2015, 119, 27695-27707]. Therefore, a series of ZnAl-LDHs were prepared by the urea method at four different reaction times (7, 12, 16, and 24 h) and characterized by bulk (PXRD, TEM, and elemental analysis) and local techniques (Al-27 SSNMR, FT-IR, and Raman spectroscopies) in combination with a time-resolved synchrotron PXRD study of the reaction mixture. The products obtained are a mixture of hydroxylated phases: an ill-defined aluminum hydroxide with similarities to gibbsite precipitates at 7 h, which is followed by a competitive formation of a crystalline ZnAl-LDH (approximate to 8 h) and a poorly crystalline hydrozincite during the later stages of the reaction. Their relative concentrations vary depending on the synthesis conditions, e.g., reaction time, urea/metal ratio, metal source, and hydrothermal treatment post synthesis, with less than half of the total Al3+ content incorporated in ZnAl-LDHs according to solid state Al-27 NMR. Thus, the preparation of highly crystalline and pure LDHs remains a challenge. Furthermore, these impurities will have a significant impact on application studies using LDHs prepared by the urea method.

KW - HYDROTALCITE-LIKE COMPOUNDS

KW - AL-27 NMR-SPECTROSCOPY

KW - SOLID-STATE NMR

KW - GAMMA-ALUMINA

KW - STRUCTURAL-CHARACTERIZATION

KW - CRYSTAL-STRUCTURE

KW - NEUTRAL PH

KW - HYDROZINCITE

KW - STABILITY

KW - OXIDE

U2 - 10.1039/c7ta05761j

DO - 10.1039/c7ta05761j

M3 - Journal article

VL - 5

SP - 21795

EP - 21806

JO - Journal of Materials Chemistry A

JF - Journal of Materials Chemistry A

SN - 2050-7488

IS - 41

ER -