Improvement of the thermal stability of hydrous zirconia by post-synthesis treatment with NaOH and NH4OH solutions

G. Aguila, S. Guerrero, F. Gracia, P. Araya

Resultado de la investigación: Article

21 Citas (Scopus)

Resumen

The structural stability of a commercial hydrous zirconia and a hydrous zirconia synthesized in our laboratory by the sol-gel method has been improved by a post-synthesis reflux treatment with aqueous NH4OH and NaOH solutions (100 °C for 9 h). Direct calcination of both materials at 700 °C for 3 h, rendered zirconium oxides with a mixture of monoclinic and tetragonal structures and specific areas of 36 and 27 m2/g, respectively. In contrast, if the materials were refluxed before calcination with NaOH or NH4OH solutions, zirconium oxides with tetragonal structure and specific areas between 90 and 200 m2/g were obtained after calcination at 700 °C. In the treatments with NaOH solution, addition of Si coming from dissolution of the flask glass walls or from an external Si source in a plastic flask is responsible for the stability of the final zirconium oxides. Nevertheless, the porous structure of these materials is determined by the treatment conditions in basic solution, thus allowing to control the physical properties of the final oxide. Short treatment times are sufficient to stabilize the hydrous zirconia. On the contrary, if the reflux is made with a NH4OH solution, the stabilization mechanism appears to be different since there is no evidence of Si addition in the oxides. In this case, the pore size distribution strongly depends on the reflux time, and the highest specific area is obtained for the largest treatment time (9 h).

Idioma originalEnglish
Páginas (desde-hasta)219-232
Número de páginas14
PublicaciónApplied Catalysis A: General
Volumen305
N.º2
DOI
EstadoPublished - 24 may 2006

Huella dactilar

Zirconia
Thermodynamic stability
Calcination
Oxides
Contrast Media
Sol-gel process
Pore size
zirconium oxide
Dissolution
Stabilization
Physical properties
Plastics
Glass

ASJC Scopus subject areas

  • Catalysis
  • Process Chemistry and Technology

Citar esto

@article{a9bde00379ee4f07b8e20aa29e62d68c,
title = "Improvement of the thermal stability of hydrous zirconia by post-synthesis treatment with NaOH and NH4OH solutions",
abstract = "The structural stability of a commercial hydrous zirconia and a hydrous zirconia synthesized in our laboratory by the sol-gel method has been improved by a post-synthesis reflux treatment with aqueous NH4OH and NaOH solutions (100 °C for 9 h). Direct calcination of both materials at 700 °C for 3 h, rendered zirconium oxides with a mixture of monoclinic and tetragonal structures and specific areas of 36 and 27 m2/g, respectively. In contrast, if the materials were refluxed before calcination with NaOH or NH4OH solutions, zirconium oxides with tetragonal structure and specific areas between 90 and 200 m2/g were obtained after calcination at 700 °C. In the treatments with NaOH solution, addition of Si coming from dissolution of the flask glass walls or from an external Si source in a plastic flask is responsible for the stability of the final zirconium oxides. Nevertheless, the porous structure of these materials is determined by the treatment conditions in basic solution, thus allowing to control the physical properties of the final oxide. Short treatment times are sufficient to stabilize the hydrous zirconia. On the contrary, if the reflux is made with a NH4OH solution, the stabilization mechanism appears to be different since there is no evidence of Si addition in the oxides. In this case, the pore size distribution strongly depends on the reflux time, and the highest specific area is obtained for the largest treatment time (9 h).",
keywords = "High surface area, NaOH treatment, NHOH treatment, Zirconium oxide",
author = "G. Aguila and S. Guerrero and F. Gracia and P. Araya",
year = "2006",
month = "5",
day = "24",
doi = "10.1016/j.apcata.2006.03.025",
language = "English",
volume = "305",
pages = "219--232",
journal = "Applied Catalysis A: General",
issn = "0926-860X",
publisher = "Elsevier",
number = "2",

}

Improvement of the thermal stability of hydrous zirconia by post-synthesis treatment with NaOH and NH4OH solutions. / Aguila, G.; Guerrero, S.; Gracia, F.; Araya, P.

En: Applied Catalysis A: General, Vol. 305, N.º 2, 24.05.2006, p. 219-232.

Resultado de la investigación: Article

TY - JOUR

T1 - Improvement of the thermal stability of hydrous zirconia by post-synthesis treatment with NaOH and NH4OH solutions

AU - Aguila, G.

AU - Guerrero, S.

AU - Gracia, F.

AU - Araya, P.

PY - 2006/5/24

Y1 - 2006/5/24

N2 - The structural stability of a commercial hydrous zirconia and a hydrous zirconia synthesized in our laboratory by the sol-gel method has been improved by a post-synthesis reflux treatment with aqueous NH4OH and NaOH solutions (100 °C for 9 h). Direct calcination of both materials at 700 °C for 3 h, rendered zirconium oxides with a mixture of monoclinic and tetragonal structures and specific areas of 36 and 27 m2/g, respectively. In contrast, if the materials were refluxed before calcination with NaOH or NH4OH solutions, zirconium oxides with tetragonal structure and specific areas between 90 and 200 m2/g were obtained after calcination at 700 °C. In the treatments with NaOH solution, addition of Si coming from dissolution of the flask glass walls or from an external Si source in a plastic flask is responsible for the stability of the final zirconium oxides. Nevertheless, the porous structure of these materials is determined by the treatment conditions in basic solution, thus allowing to control the physical properties of the final oxide. Short treatment times are sufficient to stabilize the hydrous zirconia. On the contrary, if the reflux is made with a NH4OH solution, the stabilization mechanism appears to be different since there is no evidence of Si addition in the oxides. In this case, the pore size distribution strongly depends on the reflux time, and the highest specific area is obtained for the largest treatment time (9 h).

AB - The structural stability of a commercial hydrous zirconia and a hydrous zirconia synthesized in our laboratory by the sol-gel method has been improved by a post-synthesis reflux treatment with aqueous NH4OH and NaOH solutions (100 °C for 9 h). Direct calcination of both materials at 700 °C for 3 h, rendered zirconium oxides with a mixture of monoclinic and tetragonal structures and specific areas of 36 and 27 m2/g, respectively. In contrast, if the materials were refluxed before calcination with NaOH or NH4OH solutions, zirconium oxides with tetragonal structure and specific areas between 90 and 200 m2/g were obtained after calcination at 700 °C. In the treatments with NaOH solution, addition of Si coming from dissolution of the flask glass walls or from an external Si source in a plastic flask is responsible for the stability of the final zirconium oxides. Nevertheless, the porous structure of these materials is determined by the treatment conditions in basic solution, thus allowing to control the physical properties of the final oxide. Short treatment times are sufficient to stabilize the hydrous zirconia. On the contrary, if the reflux is made with a NH4OH solution, the stabilization mechanism appears to be different since there is no evidence of Si addition in the oxides. In this case, the pore size distribution strongly depends on the reflux time, and the highest specific area is obtained for the largest treatment time (9 h).

KW - High surface area

KW - NaOH treatment

KW - NHOH treatment

KW - Zirconium oxide

UR - http://www.scopus.com/inward/record.url?scp=33646122681&partnerID=8YFLogxK

U2 - 10.1016/j.apcata.2006.03.025

DO - 10.1016/j.apcata.2006.03.025

M3 - Article

AN - SCOPUS:33646122681

VL - 305

SP - 219

EP - 232

JO - Applied Catalysis A: General

JF - Applied Catalysis A: General

SN - 0926-860X

IS - 2

ER -