Advanced search
Start date
Betweenand
Related content
(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Relevance of sol-gel transition and spinodal decomposition for hierarchical porosity structure of monolithic alumina

Full text
Author(s):
Passos, Aline R. [1, 2] ; Pulcinelli, Sandra H. [2] ; Santilli, V, Celso
Total Authors: 3
Affiliation:
[1] Brazilian Ctr Res Energy & Mat CNPEM, Brazilian Synchrotron Light Lab LNLS, BR-13083970 Campinas, SP - Brazil
[2] V, UNESP Univ Estadual Paulista, Inst Quim, Rua Prof Francisco Degni 55, BR-14800900 Araraquara, SP - Brazil
Total Affiliations: 2
Document type: Journal article
Source: Journal of Sol-Gel Science and Technology; SEP 2021.
Web of Science Citations: 0
Abstract

In situ techniques were used to investigate the hierarchical porous structure of alumina monoliths formed by the combined processes of sol-gel transition and spinodal phase separation. The addition of low molecular weight poly(ethylene oxide) (PEO) in the sol-gel reaction of aluminum chloride induced phase separation between aluminate gel and PEO solvent. In situ time-resolved small-angle X-ray scattering (SAXS) measurements revealed that structural evolution during gelation of a sample without PEO was dominated by Ostwald ripening. With PEO addition, this coarsening mechanism, occurring during a short intermediate stage (6 min), was followed by the aggregative coalescence of phase separating domains during the late stage of spinodal decomposition. The effect of PEO in the gelation mechanism also influenced the porous structure formed by calcination of the alumina monoliths. During calcination for PEO removal and conversion from xerogel to ceramic, in situ SAXS monitoring evidenced that the formation of mesopores followed the spinodal decomposition mechanism proposed by Cahn's theory. Alumina with well-defined meso- and macropore families, high specific pore volume (2.0 cm(3) g(-1)), and high surface area (252 m(2) g(-1)) was obtained as a result of spinodal decomposition during the sol-gel transition followed by heat treatment. {[}GRAPHICS] . (AU)

FAPESP's process: 11/08673-9 - Macro-mesoporous alumina produced by sol-gel method for application in heterogeneous catalysis
Grantee:Aline Ribeiro Passos
Support Opportunities: Scholarships in Brazil - Doctorate
FAPESP's process: 07/53073-4 - Mesoporous ceramics and multifunctional organic-inorganic hybrids prepared by sol-gel process
Grantee:Celso Valentim Santilli
Support Opportunities: Research Projects - Thematic Grants