Abstract: A catalyst for removing nitrogen oxides contained in exhaust gases, particularly those containing vapor-form catalyst poisons, by catalytic reduction with ammonia, while retaining a high denitration performance for a long time, which catalyst comprises titanium oxide as a first component, molybdenum oxide and/or tungsten oxide as a second component and vanadium oxide and/or sulfate as a third component, the atomic ratio of the respective elements being Ti:Mo and/or W:V=80-96.6:3-15:0.5-5, and the size of the crystallite of the titanium oxide according to Sherrer's equation being in the range of 185 .ANG. to 300 .ANG. in the direction of a plane (101) (interplanar spacing: d=3.52 .ANG.).

Abstract: A process for removing nitrogen oxides from exhaust gases containing volatile metal compounds with good efficiency by contacting the gases with a catalyst comprising TiO.sub.2, difficulty reduced by the compounds, in the presence of ammonia, and such a catalyst are provided, which process is characterized in that the average pore diameter of the TiO.sub.2 is 10,000 .ANG. or less and the proportion of the volume of pores having pore diameters of 400-5,000 .ANG. to the total pore volume is 50% or more; a denitration-active component is supported on the TiO.sub.2 ; a catalyst carrier precursor comprising an aqueous slurry sol of TiO.sub.2 or Ti hydroxide prepared by hydrolyzing a Ti salt is precalcined at 150.degree.-700.degree. C., followed by adding a denitration-active component and then normally calcining the mixture; and a polymer compound having a thermal decomposition temperature of 110.degree. to 300.degree. C.

Abstract: A process for removing nitrogen oxides from exhaust gases containing at least nitrogen oxides and volatile metal compounds by the use of a catalyst having prevented activity reduction due to the volatile metal compounds and having a superior durability is provided, which process comprises contacting the exhaust gases with a catalyst containing TiO.sub.2, a compound active to nitrogen oxides-removing reaction such as oxides of V, Cr, Mo, W, Fe, Co, Ni, Cu, Ce, etc. and/or sulfates thereof and a metal sulfate containing water of crystallization such as those of Al, Mg or Mn, in the presence of ammonia at 150.degree. to 600.degree. C.

Abstract: A catalyst for removing nitrogen oxides whose activity deterioration due to volatile poisons contained in exhaust gases is prevented and which has a superior endurance, and a process for producing the catalyst are provided, which catalyst comprises a titania having a surface area of 20 m.sup.2 /g or less and a zeolite having 0.01 to 20% by weight of copper supported thereon; having an average pore diameter of 10 .ANG. or less; and having a silica/alumina molar ratio of 10 or more, and which process comprises mixing powder of the zeolite with the titania or its precursor, followed by molding the mixture into a predetermined shape, followed by calcining the resulting material at 800.degree. C. or higher.

Abstract: A high performance catalyst for combustion having a cheap and heat-resistant carrier capable of retaining a high specific surface area even when it is used at a high temperature of 1,000.degree. C. or higher for a long time, and a process for producing the same are provided, which catalyst comprising a compound expressed by a composition formula of BaAl.sub.12 O.sub.19, and said process comprises kneading .gamma.-alumina or aluminum hydroxide and a barium compound or impregnating the former compound with the latter so as to give an atomic ratio of Al/Ba in the range of 100/1 to 100/15, followed by calcination.

Abstract: An ammonia reduction-denitration process for exhaust gases containing NO.sub.x consisting mainly of NO.sub.2, and an apparatus therefor are provided, which process comprises treating the exhaust gases with ammonia using a catalyst which is active to both a reaction of (NO.sub.2 +NH.sub.3 .fwdarw.N.sub.2 +N.sub.2 O+H.sub.2 O) and a reaction of (N.sub.2 O+NH.sub.3 .fwdarw.N.sub.2 +H.sub.2 O) at an area velocity of 3 m/h or less and in a concentration ratio of NH.sub.3 /NO.sub.2 of 1.3 or more. According to this process, it is possible to reduce NO.sub.2 contained in the exhaust gases with ammonia at one stage without by-producing N.sub.2 O.