CATALYST AND A METHOD FOR DENITRIZING NITROGEN OXIDES CONTAINED IN WASTE GASES

摘要

27571-11 A catalyst for denitrizing nitrogen oxides contained in waste gases in the presence of arsenic compounds, which comprises: titanium and vanadium therein in titanium:vanadium weight ratio of from 99.9:0.1 to 92.0:8.0, the vanadium being concentratedly contained in a surface layer of the catalyst of a thickness of up to 200 .mu.m from the surface of the catalyst in a concentration of at least about 1.5 times higher than average concentration of vanadium in the whole catalyst. The catalyst may further contain therein at least one of tungsten and zirconium. The catalyst has micropores of about not less than about 50 .ANG. in an amount of 0.25-0.40 ml/g, and micropores of about 50-100 R in radius in an amount of about 10-40% by volume and micropores of about 100060000 R in radius in an amount of not less than about 10% by volume, respectively, based on the total volume of the micropores of not less than about 50 .ANG. in radius. The catalyst retains a higher denitrizing activity over a long period of denitrizing operations in the presence of arsenic compounds contained waste gases than the conventional catalysts.