10
th
International Symposium “Scientific Bases for the Preparation of Heterogeneous Catalysts”
E.M. Gaigneaux, M. Devillers, S. Hermans, P. Jacobs, J. Martens and P. Ruiz (Editors)
© 2010 Elsevier B.V. All rights reserved.
Solution Combustion Synthesis as intriguing
technique to quickly produce performing catalysts
for specific applications
Stefania Specchia, Camilla Galletti, Vito Specchia
Politecnico di Torino, Department of Materials Science and Chemical Engineering,
Corso Duca degli Abruzzi 24, 10129 Torino, Italy
Abstract - rewritten
Solution Combustion Synthesis (SCS) is becoming one of the most important ways to
produce a wide range of advanced porous ceramic or metallic materials. These include
ceramic oxide like nanostructured catalysts. SCS is an attractive alternative for the
production of smart materials of high value compared to the more conventional and
expensive preparation routes. SCS processes are characterized by relative medium
heating oven temperatures (350-600°C), fast heating rates, short reaction times and very
small residence time at high temperature. The final product is usually of high purity and
well crystallized with nanometric size clusters. Furthermore, SCS, suitably adapted, is
easily tunable to complex industrial supports to produce directly in situ structured
catalysts.
The present work deals with the analysis of low-environmental-impact premixed
metal fiber burners (FeCrAlloy® fiber mat) for household applications. New catalytic
burners based on Pd(LaMnO
3
·2ZrO
2
) catalyst were developed and tested in a partially
modified commercial condensing boiler test rig fed with natural gas (NG). The catalytic
burner presented a lower environmental impact, compared to the commercial bare
burner, mainly in terms of CO. NO emissions were reduced, too, but in a slightly lower
extent. The catalytic burner better stabilized the combustion process within the porous
medium, maximizing the heat fraction transferred by radiation, cooling the flame
temperature and enhancing the degree of completeness of NG combustion.
Keywords: solution combustion synthesis, nanomaterials, catalysts, nitrate precursors,
organic fuel, domestic appliances, natural gas combustion, CO/NO emissions
1. Introduction
The chemical processing and synthesis of high performance technological catalysts
requires the use of high purity precursors. Recently several attempts have been made to
find out an intriguing technique to quickly produce performing catalysts for any kind of
industrial application. In particular, methods based on “solution combustion synthesis”
(SCS) have received a remarkable interest. These processes, in fact, make use of highly
exothermic redox chemical reactions between metals and non-metals, to synthesize the
desired ceramic nanomaterials [1-3].
SCS means the synthesis of compounds in a wave of chemical reaction (combustion)
that propagates over starting reactive mixture owing to layer-by-layer heat transfer.
Practically, it is an exothermic redox process in which the reaction between two or more
reactants takes place in a self-sustaining regime leading to the formation of solid
products of a higher value [1]. It is widely well-known in catalysis, that nanosized
catalysts possess extremely high activity and selectivity [4,5]. Compared to other