resumo
Alumina-based open cellular microstructures with highly interconnected porosity attract much interest as supports for catalytic applications, with emphasis on petroleum and automotive sector. This work reports a novel route for in-situ functionalization of the sintered porous alpha-Al2O3 ceramics by micro/nano structures of boehmite (gamma-AlOOH), promoted by hydrothermal treatment in alkaline conditions. The mechanism of the process includes slow dissolution of the matrix, which acts as an aluminum precursor, and transport of Al-containing species inside the pores, resulting in growth of boehmite fibers and clusters of various morphologies, as confirmed by combined SEM/EDS/XRD/FTIR. These results suggest that deliberate variation of the pH and ionic strength of the hydrothermal medium may represent a promising strategy for controlling the spatial distribution, morphology and dimension scale of the grown boehmite. A complementary approach implies pre-treatment of cellular monoliths in highly-reducing conditions to increase the concentration of surface defects and dangling bonds, facilitating the matrix dissolution and probably acting as nucleation centers, and thus to boost the functionalization level. (C) 2015 Elsevier Ltd. All rights reserved.
palavras-chave
PARAFFIN EMULSIFIED SUSPENSIONS; BOEHMITE NANOPARTICLES; DISSOLUTION; EVOLUTION; GIBBSITE; SURFACE
categoria
Materials Science
autores
Vitorino, NMD; Kovalevsky, AV; Azevedo, MCC; Abrantes, JCC; Frade, JR
nossos autores
Andrei Kavaleuski
Investigador principal
João Carlos de Castro Abrantes
Professor Adjunto
Jorge Ribeiro Frade
Professor(a) Jubilado(a)
Maria Celeste Coimbra Azevedo
Técnico de Laboratório
Nuno Miguel Dias Vitorino
Bolseiro de pós-DoutoramentoProjectos
CICECO - Aveiro Institute of Materials (UID/CTM/50011/2013)
Cellular oxide catalysts for emission lean combustion in porous media (LEANCOMB)
agradecimentos
This work was developed in the scope of the project CICECO-Aveiro Institute of Materials (Ref. FCT UID/CTM/50011/2013, PTDC/CTM-ENE/2942/2014 and PEst-C/CTM/LA0011/2013, and grants SFRH/BPD/99367/2013 and IF/00302/2012), financed by National funds through the FCT/MEC and when applicable co-financed by FEDER under the PT2020 Partnership Agreement. SEM and XRD facilities were funded by FEDER Funds through QREN-Aviso SAIECT-IEC/2/2010, Operacao NORTE-07-0162-FEDER-000050.