MIXED METAL OXIDIC NANO SHEETS COATED MONOLITHIC CATALYSTS USEFUL FOR THE DECOMPOSITION OF TOXIC N2O AND A PROCESS FOR THE PREPARATION THEREOF

摘要

In the present invention there is provided a process for the preparation of nano-oxide coated catalysts useful for the treatment of toxic gases by coating of composite materials containing LDHs over ceramic monolithic substrates. The process combines reacting oxides and salts of metals in a known manner so as to prepare LDHs or mixed metal layered hydroxides such as Ni-Al, Mg-Al, Zn-Cr-Al type possessing positive layer charge, from which a stable gel is prepared by adding swellable clay having a negative charge e.g. montmorillonite, laponite, hectorite etc. in different LDH:clay ratio in an aqueous medium and homogenising the same with high speed homogeniser and ultrasonicator in a high intensity ultrasonic processor. The gel is then dip-coated over cordierite/mulite honey-comb monolithic supports at various dipping and withdrawal rates. The dip-coated monoliths are then dried and calcined at different temperatures to develop the alumino-silicate supported nano-oxide coats over honey-comb ceramic substrates for carrying out decomposition of N2O gas in a He flow in various flow rates at 400 to 600oC temperature in a cylindrical quartz tube.