Catalytic combustion can be regarded as an intrinsically clean and safe technology which allows a primary air pollution control, since energy is produced with high efficiency burning fuel/air mixtures also outside the flammability limits, at operating temperatures far lower than those of flame combustion and without the instability problems and pollutants (CO, NOx, soot and unburned hydrocarbons) typical of the traditional processes (fig.1). Moreover the catalytic oxidative conversion of natural gas and light hydrocarbons represents an attractive route for the sustainable production of valuable building block intermediates and chemicals such as synthesis gas or ethylene and propylene. All of these processes require high temperature resistant catalysts (800-1100°C or more) with high intrinsic activity in order to cope with extremely reduced contact times normally employed. Typically, catalyst compositions for such processes have included precious metals (and/or rare earths) since Pt, Pd, Rh are commonly recognised among the most effective active components; nevertheless, their use in high temperature applications is strongly limited by problems of stability (PdO) and volatility (Pt). Moreover the large volumes of expensive catalysts needed, have placed those processes generally outside the limits of economic justification.
In recent years, a lot of research effort has been devoted at the Istituto di Ricerche sulla Combustione to the study of alternative active phases. In particular novel catalysts have been developed with improved and balanced properties of thermal resistance and intrinsic oxidation activity which are based on inexpensive perovskite-type oxides supported on high surface area refractory materials. Structured monolithic catalysts, prepared in a variety of shapes from such novel active phase (fig 2), have been employed for the lean premixed combustion of methane, showing an elevated specific oxidation activity, a thermal stability and durability markedly higher than corresponding bulk perovskite up to 1100°C, which make them suitable candidates for the domestic and industrial applications in premixed radiant burners and/or gas turbine combustors.
Moreover, such novel catalyst were found to perform better than state of the art Pt catalysts in short contact time reactors for the partial oxidation of ethane to produce ethylene, renewing industrial interest to substitute the large existing cost intensive and polluting steam cracking units.
The research activity has driven CNR to the deposit of an Italian patent in 2003, which is presently being extended worldwide in collaboration with industrial partners, and to the ITALGAS 2003 Prize for the Debut in Research recently awarded to Dr. Francesco Donsì for his PhD thesis carried out at the Istituto di Ricerche sulla Combustione.
Indeed this research activity has attracted high profile industrial partners (ENEL, SNAMPROGETTI) which are currently financing new projects for the evaluation and implementation of the novel systems developed in profitable technological applications for the production of both clean energy (Gas Turbines Combustors) and chemicals (Ethylene)
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