Patents

In the invention a process is provided for the preparation of nano-oxide coated adsorbent useful for treatment of toxic gases by coating of composite materials containing hydrotalcite over ceramic monolithic substrates. The process combines reacting oxides and salts of metals in a known manner so as to prepare hydrotalcites or mixed metal layered hydroxides such as Mg-A1, Ca-A1, Zn-Al, Zn-Cr type possessing positive layer charge, from which a stable gel is prepared by adding swellable clay having a negative charge e.g. montmorillonite etc. in different hydrotalcite: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 alurnino-silicate supported nano-oxide coats over honey-comb ceramic substrates for carrying out adsorption of H2S and SO2 gas in a He flow in various flow rates at 400 to 1000°C temperature in a cylindrical quartz tube.