Abstract: A catalyst for denitrizing nitrogen oxides contained in waste gas which contains a substantial amount of arsenic compounds therein, which comprises:(a) titanium, and(b) at least one element selected from the group consisting of arsenic and manganese. The catalyst is resistant to deactivation by arsenic compounds and retains high denitrizing activity over a long period of time. The catalyst may further contain at least one base metal selected from the group consisting of V, W, Mo, Cu, Fe, Cr, Co, Ni, Zn and Sn.

Abstract: A catalyst for denitrizing nitrogen oxides contained in waste gases, which comprises:(a) titanium, and(b) at least one base metal selected from the group consisting of V, W, Mo, Mn, Cu, Fe, Cr, Co, Ni, Zn and Sn, the catalyst containing titanium and the base metals in amounts of at least about 50% by weight in terms of oxides based on the catalyst, and titanium in amounts of about 80-99% by weight in terms of oxides and the base metals in amounts of about 20-1% by weight in terms of oxides, respectively, based on the total weight in terms of oxides of titanium and the base metals, and the catalyst having micropores of about 50-75000 .ANG. in radius in amounts of about 0.25-0.45 ml/g, and micropores of about 50-100 .ANG. in radius in amounts of about 10-40% by volume and micropores of about 500-60000 .ANG. in radius in amounts of not less than about 10% by volume, respectively, based on the total volume of the micropores of about 50-75000 .ANG.

Abstract: A method is provided for producing a catalytic structure in the form of sheet or honeycomb for the gas phase reduction of nitrogen oxides. The method comprises: beating an inorganic fiber in water to form a slurry; forming the slurry into a sheet by paper-making means and drying the sheet; impregnating the sheet or a honeycomb structure manufactured therefrom which has a porosity of 60-85% with an impregnating slurry which contains titanium dioxide or its precursor in a concentration at least of 100 g/l and has a viscosity of 5-250 cps. at normal temperatures, drying, and when necessary calcining the structure; and then immersing the structure in a solution containing a catalytically active agent or its precursor, drying and calcining the structure, thereby to provide a porous catalytic structure having titanium dioxide and the catalytically active agent substantially uniformly dispersed and supported therein.

Abstract: A method is provided for producing a catalyst and a carrier therefor in the form of sheet or honeycomb. The method comprises: beating a heat-resistant fiber such as asbesto fiber in water to form a slurry; mixing the slurry with a catalytically active agent, a carrier material therefor and/or their precursors to fix such materials in the fiber, thus forming a stock; and forming the stock into a sheet and drying the same. The sheet thus obtained may be formed into a honeycomb structure with an improved adhesive.

Abstract: A method for packing catalysts comprising packing the catalysts having through-holes in the direction of the flow of the gas with plurality of them being arranged in the direction of the flow of the gas through the catalyst-packed layers, characterized by arranging the catalysts in such manner that the sections of the connecting parts in the direction of the flow of the gas do not lie on the same plane as at least one of the above sections of the connecting parts formed by the adjacent catalysts.

Abstract: In a method for treating a gas containing dusts therein under a monolithic catalyst consisting of a ceramic support which is substantially porous throughout the structure, and has active ingredients uniformly dispersed therein and passages therethrough parallel to the flow of the gas for allowing the gas to pass therethrough, the improvement in which the catalyst has the sintered front portion or has a vitreous coating on the front portion. Alternatively, the improvement in which a metal or sintered ceramic lid having openings therethrough is fixed onto the front face of the catalyst with the passages in alignment with the openings of the lid.

Abstract: A method is provided for producing a catalyst and a carrier therefor in the form of sheet or honeycomb. The method comprises: beating a heat-resistant fiber such as asbesto fiber in water to form a slurry; mixing the slurry with a catalytically active agent, a carrier material therefor and/or their precursors to fix such materials in the fiber, thus forming a stock; and forming the stock into a sheet and drying the same. The sheet thus obtained may be formed into a honeycomb structure with an improved adhesive.