JPS5727139A - Catalyst body for purifying gas - Google Patents

Abstract

PURPOSE:To obtain catalysts which are excellent in heat resistance and have a long life by preventing the sintering of metallic oxides, by mixing a proper amount of titanium oxide into lime aluminate and transition metallic oxides. CONSTITUTION:This is a catalyst for purifying waste gases which consists essentially of lime aluminate, transition metallic oxides, and titanium oxide. The titanium oxide content in this catalyst is 5-50wt%. The lime aluminate is usually represented by alumina cement which is expressed as mAl2O3.n CaO, and as the Al2O3 content becomes higher, the heat resisting property becomes more excellent and the mixed iron oxide exhibits stronger cocatalystic effect. As for the TiO2, anatase type is more desirable than rutile type because of its heat stability. Moreover composite oxide, such as TiO2-Al2O3, TiO2-ZrO3, etc., can also be used as the TiO2 source. When the TiO2 content is less than the lower limit, its adding effect cannot be expected, and, in contrary, when more than the upper limit, the other essential elements become less and, as a result, the binding force becomes weaker and the catalyst cannot stand when it is used. The above-mentioned essential elements are mixed with water whose amount is just enough for forming, and the mixture is solidified after forming and aging.