Preparation, characterization and deposition of Langmuir-Blodgett Co, Al organic films for the catalytic applications

VOC combustion is a demanding process for both reactor and catalyst design. As we have proved in recent papers the diffusional limitation of reaction rate that occur during combustion may be overcome by designing the metallic microstructures used as reactor internals. Their application on industrial scale depends on the development of an efficient method of catalyst layering on metallic supports and optimisation of a fine catalyst structure which would not change the elaborated microstructure geometry. In this study we propose the Langmuir-Blodgett (LB) film method to deposit various metals (Al, Co) in form of catalyst organic precursors. The film forming abilities of the precursors were checked by surface pressure measurements upon film compression, Brewster Angle Microscopy and by monolayers stability measurements. The amount of deposited materials was controlled by the LB parameters and verified by TG measurements. The catalyst obtained in this way were characterized at various stages of the preparation by SEM/XFS, XPS, AFM and RM methods and tested in n-hexane combustion. Oxidation of the Al washcoat precursor led to the formation of gamma-Al2O3 improving the properties of the Al2O3 layer (a phase) developed on the precalcined CrAl carrier. Oxidation of cobalt stearate deposited on the CrAl gave dispersed Co3O4 spinel. The cobalt catalysts were active in combustion showing resistance to sintering, Compared to standard Pt supported catalyst they had twice as low activation energy (50 kJ/mol). (c) 2005 Elsevier B.V. All rights reserved.