Abstract:
A method for decomposing carbon dioxide using the barium ferrite is provided to decompose almost 100% of carbon dioxide at a quick reaction rate, and to be capable of operating processes continuously by cyclone type of recovery method. A method for decomposing carbon dioxide using the barium ferrite includes the steps of: performing a hydrolysis reaction of an aqueous alkali solution(2) and a mixture(1) of aqueous nitrate solutions containing iron and barium at ambient temperature under a reaction pressure of 30-50 MPa; supplying preheated water(6) to the hydrolysis reaction step to raise the reaction temperature to 100-400 °C, and staying the preheated water for 3-10 seconds to form critical nuclei; supplying preheated water(8) to heat the hydrolysate to the supercritical temperature for water, performing a final dehydration reaction in a reactor(9) maintaining a supercritical state to collect barium ferrite continuously; and hydrogenating the barium ferrite, and then reacting the hydrogenated barium ferrite with carbon dioxide.
Abstract:
PURPOSE: A preparation method of barium titanate powder by hydrothermal synthesis is provided, which prevents corrosion of powder preparation equipment and lowers production cost by using Ba and Ti hydroxides as raw materials instead of conventional raw materials containing chlorides. CONSTITUTION: The continuous preparation method of fine and homogeneous BaTiO3 powder through hydrothermal process comprises the steps of: (i) mixing barium hydroxide, Ba(OH)2-8H2O, with titanium hydroxide, TiO(OH)2 in a concentration ratio of 0.5-2 : 1 under pressure of 10-40MPa, which is expressed by the formula TiO(OH)2 + Ba(OH)2-8H2O -->BaTiO3 +10H2O; (ii) supplying hot water to the mixture for 100-400deg.C of mixture; (iii) reacting 3-10sec. to form critical nuclei; (iv) supplying hot water to the intermediates forming critical nuclei, and dehydrating under subcritical and supercritical state to get BaTiO3; (v) separating synthesized materials and recycling.