| 摘要 |
<p>PURPOSE:To treat a large quantity of exhaust gas at comparatively low temp. with inexpensive catalyst which is hardly poisoned by SO2 etc. contained in the exhaust gas, by catalytic reaction of the exhaust gas contg. NOx with NH3 in the presence of laterite catalyst. CONSTITUTION:Laterite, or laterite having been pretreated with aq. soln. of inorg. acid and dried, is adjusted to a suitable moisture content, and is subjected to extrusion molding or rolling granulation in order to shape it into particles. The molded material is dried at 50-150 deg.C, calcined at 350-800 deg.C, pref, at 400-600 deg.C, to prepare catalyst. In the presence of the catalyst, the exhaust gas contg. NOx is then made to come into contact with NH3 to reduce NOx to N2. The temp. at which the catalytic reaction is effected is usually 200-500 deg.C, pref. 250-500 deg.C. The quantity of NH3 fed to the gas is pref. 0.8-2.0 mols per mol NO. The presence of O2 in the reaction system accelerates the reduction, and the simultaneous presence of water and SO2 to the extent 15% and 400 ppm respectively scarcely decreases the denitration ratio.</p> |
