Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

PP-III-6CATALYTIC SELF CLEANING PROCESS FOR DOMESTIC OVENP. Faraldi 2 , P. Palmisano 1 , N. Russo 1 , D. Fino 1 , G. Saracco 1 and V. Specchia 11 Materials Science and Chemical Engineering Department, Politecnico di Torino,C.so Duca degli Abruzzi 24, Torino 10129 Italy,phone/fax: +39 011 0904710/4699, e-mail: nunzio.russo@polito.it2 Indesit Company, Innovation and Technology Department,Via Lamberto Corsi 55, Fabriano (AN) 60044 Italy, phone/fax: +39 0732 668330/8201Household ovens cleaning process is an issue both for customers and manufacturers,today performed by apposite caustic detergents or via high temperature (> 500°C) incinerationcycles. Oven soiling is mainly constituted by fatty acids splatters, thermally degraded by theprolonged exposure to oven wall temperatures (up to 300 °C), strongly adhered to wallthemselves. The present work aimed to provide oven walls with self cleaning properties, viacatalytically enhanced thermal oxidation of soil at temperatures within the available range ofstandard ovens.First, representative organic compounds were identified to be used to test possible catalystformulations: for this purpose saturated fatty acids, as myristic (tetradecanoic), palmitic(hexadecanoic), stearic (octadecanoic) acid were selected. In a second step it was also testedthe olive oil and the butter as real compounds present in a domestic oven. A preliminarythermal degradation behavior of such compounds were characterised via TGA (ThermoGravimetric Analysis), in different conditions (partially thermally degraded) and atmospheres(air, 5% O 2 and 0,5% O 2 with the N 2 balance).Three oxidative catalyst types were selected: Spinels (CoCr 2 O 4 , MnCr 2 O 4 , MgFe 2 O 4 andCoFe 2 O 4 ), Perovskites (LaFeO 3 and LaCrO 3 ) and Lanthanoids Oxides (La 2 O 3 and CeO 2 ). Allthe catalysts were prepared by Solution Combustion Synthesis method, a fast and selfsustainingchemical reaction between metal nitrate precursors and urea or glycine assacrificial fuel [1]. The catalytic activity has been tested in a temperature programmedoxidation (TPO) apparatus. This equipment consists of a fixed bed inserted in a quartzmicroreactor (i.d.:4 mm). The fixed bed was prepared by mixing 50 mg of a 1:9 by weightmixture of fatty acid and catalyst in powder. The TPO runs were performed increasing thetemperature from room temperature to 700 °C at a 5 °C/min rate, under an air flow of 100 Nml/min. This experiment was set up to evaluate the activity of pure catalyst towards selectedfatty acids oxidation, monitoring CO 2 and CO concentration resulting from organiccompounds oxidation and using concentration peaks as term of comparison for identifyingmaximum activity temperature. The temperature corresponding to the CO 2 concentration peak313