Abstract: This invention discloses an adsorbent ideal or the removal of nitrogen oxides (NO.sub.x : nitrogen monoxide and nitrogen dioxide), particularly nitrogen dioxide, from an exhaust gas containing the nitrogen oxides at low concentrations and a method for efficient removal of nitrogen oxides, particularly nitrogen dioxide, from an exhaust gas containing the nitrogen oxides at low concentrations by the use of the adsorbent. The adsorbent either comprises at least one noble metal selected from the group consisting of Pt, Au, Ru, Rh, and Pd and/or a compound thereof supported on a carrier or comprises the noble metal component and an oxide of at least one heavy metal selected from the group consisting of Mn, Fe, Co, Ni, Cu, Zn and Pb, which may be supported on the carrier, if necessary.

Abstract: A honeycomb catalyst for effecting catalytic reduction and removal of nitrogen oxides in waste gas in the presence of ammonia, which homeycomb catalyst (I) contains a catalytically active substance comprising 60 to 99.5% by weight of a binary oxide containing titanium and silicon and 40 to 0.5% by weight of the oxide of at least one metal selected from the group consisting of vanadium, tungsten, molybdenum, copper, manganese, cerium, and tin, (II) possesses an opening ratio in the cross section of said catalyst in the range of 80 to 90%, (III) has a thickness of partition walls separating through holes in the range of 0.2 to 0.8 mm, and (IV) possesses pores comprising substantially two independent pore groups each of a uniform pore diameter, such that the pore volume occupied by one pore group having a pore diameter in the range of 0.01 to 0.03 .mu.

Abstract: A waste gas-treating catalyst produced by coating the gas inlet side leasing end part of an integrally formed titanium-containing porous nitrogen oxide removing catalyst with at least one sol selected from the group consisting of zirconia sol and zirconium silicate sol, drying and/or calcining the coated catalyst.

Abstract: The present invention concerns a method of removing nitrogen oxides in exhaust gases from a diesel engine by using a catalyst in a reacter under the presence of ammonia, wherein a humidity of in-take air as a specific factor and one or more of engine power, fuel consumption amount of engine, temperature of engine in-take air and exhaust gas temperature as selective factors are measured respectively as the measuring factors and the flow rate of ammonia is controlled based on measured values and ammonia is supplied to an exhaust gas flow channel from the engine to the reactor.

Abstract: The present invention concerns a method of removing nitrogen oxides in exhaust gases from a diesel engine by using a catalyst in a reacter under the presence of ammonia, wherein a humidity of in-take air as a specific factor and one or more of engine power, fuel consumption amount of engine, temperature of engine in-take air and exhaust gas temperature as selective factors are measured respectively as the measuring factors and the flow rate of ammonia is controlled based on measured values and ammonia is supplied to an exhaust gas flow channel from the engine to the reactor.

Abstract: A method for the removal of nitrogen oxides from the exhaust gas of a diesel engine through catalytic reduction by the use of honeycomb catalyst in the presence of ammonia, which method comprises feeding ammonia into said exhaust gas proportionately to the product of the revolution number of said diesel engine multiplied by the torque of said diesel engine.